Category: Uncategorized

Making a simple FPGA video synth for PEW 2023 at Villette Makerz. It takes audio in and generates patterns based on the voltage threshold and the 9 keys being pressed.

The code is here : https://github.com/merlinmarrs/iCE40HX-verilog-video-patterns

This time the top interface side has only buttons and no electronics. I have a simplified VGA out and HDMI with the correct LVDS resistor setup this time. I am relying on raspberry pi or arduino for programming.

Trying a grid ground pour on the Stop layer :

Found a site called OpenCores (https://opencores.org) that has free FPGA IP like math libraries.

Here are some tests with cool looking patterns :

Because dividing, trig functions, etc. aren’t supported by default, the most promising is the bitwise boolean logic operating on the entire vector :

wire[11:0] bit_or;
assign bit_or = h_count[11:0] | v_count[11:0];

[...]

if (bit_or[5] == 1 | bit_or[3] == 0) begin

wire[11:0] bit_xor;
assign bit_xor = h_count[11:0]^v_count[11:0];

[...]

if (bit_xor[2] == 1 | bit_xor[4] == 1) begin

wire[11:0] bit_and;
assign bit_and = h_count[11:0]&v_count[11:0];

...

if (bit_and[6] == 1 | bit_xor[7] == 1) begin

I could imagine having the keys vary which logic operations are in play and having the music threshold change the color of the pixels for instance.

***

This site has a module for a quasi random number generator : https://simplefpga.blogspot.com/2013/02/random-number-generator-in-verilog-fpga.html

This site has some good Processing examples : http://www.generative-gestaltung.de/2/

***

If I do this workshop again I’d like to design it to be made on aluminum as, it is at least in principle, recyclable.

PCBWay’s diagram of a double layer board (https://www.pcbway.fr/pcb_prototype/General_introduction_of_Aluminum_PCB.html) :

***

Simplest imaginable keypad switch (and audio in post comparator) test works :

module top (
input hwclk,
output led1,
input keypad_c1
);

assign led1=keypad_c1;

endmodule

`default_nettype none

module LFSR (
input clock,
input reset,
output [12:0] rnd
);

wire feedback;
reg [12:0] random, random_done;
reg [3:0] count; //to keep track of the shifts

assign feedback = random[12] ^ random[3] ^ random[2] ^ random[0];
assign rnd = random_done;
always @ (posedge clock)
begin
if (reset)
begin
random <= 13'hF; //An LFSR cannot have an all 0 state, thus reset to FF
count <= 0;
end

else
begin
if (count == 13)
begin
count <= 0;
random_done <= random; //assign the random number to output after 13 shifts
end

else
begin
random <= {random[11:0], feedback}; //shift left the xor'd every posedge clock
count <= count + 1;
end
end
end
endmodule

wire [12:0] random_number;

[...]

LFSR random_s(
.clock(clk_in),
.reset(reset),
.rnd(random_number)
);

`default_nettype none
module tempo(
input wire clk,
output reg half_sec_pulse
);

reg[25:0] div_cntr1;
reg[25:0] div_cntr2;
always@(posedge clk)
begin
div_cntr1 <= div_cntr1 + 1;
if (div_cntr1 == 0)
if (div_cntr2 == 0)
begin
div_cntr2 <= 0;
half_sec_pulse <= ~half_sec_pulse;
end

else
div_cntr2 <= div_cntr2 + 1;
else
half_sec_pulse <= half_sec_pulse;
end

endmodule

`default_nettype none

module vga_sync_test(

input wire clk_in,
input wire reset,
input wire key[8:0],
input wire adc_in,
output reg led_red,
output reg led_green,

//VGA OUT

output reg [3:0] r_out,
output reg [3:0] b_out,
output reg [3:0] g_out,
output wire h_sync,
output wire v_sync

);

wire half_sec;
wire [12:0] random_number_0;
wire [12:0] random_number_1;
wire [12:0] random_number_2;
wire [12:0] random_number_3;
wire [12:0] random_number_4;
wire [12:0] random_number_5;
wire [12:0] random_number_6;
wire [12:0] random_number_7;
wire [12:0] random_number_8;
wire [12:0] random_number_9;
wire [7:0] sine_wave;
wire display_en;
wire [11:0] h_count;
wire [11:0] v_count;

localparam h_pixel_max = 1280;
localparam v_pixel_max = 960;
localparam h_pixel_half = 640;
localparam v_pixel_half = 480;
localparam h_pixel_25 = 320;
localparam v_pixel_25 = 240;
localparam h_pixel_75 = 960;
localparam v_pixel_75 = 700;

//VGA COLOR OUT

always @(posedge clk_in) begin

if (display_en) begin

if ( key[0] == 0 &&

h_count < h_pixel_25 + random_number_1[4:0] && v_count < v_pixel_25 + random_number_7[8:5] &&
h_count > h_pixel_25 - random_number_2[4:0] && v_count > v_pixel_25 - random_number_2[8:5]

) begin

r_out <= random_number_1[3:0];
g_out <= random_number_5[3:0];
b_out <= random_number_9[6:4];

led_green <= 1;

end

else if ( key[1] == 0 &&

h_count < h_pixel_half + random_number_7[5:0] && v_count < v_pixel_half + random_number_7[10:5] &&
h_count > h_pixel_25 - random_number_6[5:0] && v_count > v_pixel_25 - random_number_6[10:5]

) begin

r_out <= random_number_3[7:5];
g_out <= random_number_3[3:0];
b_out <= random_number_6[6:4];

led_green <= 1;

end

else if ( key[2] == 0 &&

h_count < h_pixel_25 + random_number_8[6:0] && v_count < v_pixel_25 + random_number_8[12:6] &&
h_count > h_pixel_half - random_number_9[6:0] && v_count > v_pixel_half - random_number_9[11:5]

) begin

r_out <= random_number_4[7:5];
g_out <= random_number_5[3:0];
b_out <= random_number_7[6:4];
led_green <= 1;

end

else if ( key[3] == 0 &&

h_count < h_pixel_half + random_number_0[7:0] && v_count < v_pixel_half + random_number_0[7:0] &&
h_count > h_pixel_half - random_number_3[7:0] && v_count > v_pixel_half - random_number_3[11:4]

) begin

r_out <= random_number_8[7:5];
g_out <= random_number_8[3:0];
b_out <= random_number_8[6:4];
led_green <= 1;

end

else if ( key[4] == 0 &&

h_count < h_pixel_75 + random_number_2[8:0] && v_count < v_pixel_half + random_number_2[11:3] &&
h_count > h_pixel_75 - random_number_4[8:0] && v_count > v_pixel_half - random_number_4[11:3]

) begin

r_out <= random_number_7[7:5];
g_out <= random_number_7[3:0];
b_out <= random_number_7[6:4];

led_green <= 1;

end

else if ( key[5] == 0 &&
h_count < h_pixel_half + random_number_3[9:0] && v_count < v_pixel_75 + random_number_3[11:2] &&
h_count > h_pixel_half - random_number_8[9:0] && v_count > v_pixel_75 - random_number_8[11:2]

) begin

r_out <= random_number_5[7:5];
g_out <= random_number_5[3:0];
b_out <= random_number_5[6:4];
led_green <= 1;

end

else if ( key[6] == 0 &&

h_count < h_pixel_75 + random_number_4[10:0] && v_count < v_pixel_75 + random_number_4[11:1] &&
h_count > h_pixel_75 - random_number_6[10:0] && v_count > v_pixel_75 - random_number_6[11:1]

) begin
r_out <= random_number_4[7:5];
g_out <= random_number_4[3:0];
b_out <= random_number_4[6:4];
led_green <= 1;
end
else begin
r_out <= random_number_2[3:0];
g_out <= random_number_3[6:4];
b_out <= random_number_4[3:0];
led_green <= 0;
end
end
else begin
r_out <= 4'b0000;
g_out <= 4'b0000;
b_out <= 4'b0000;
led_green <= 0;
end
end

vga_sync vga_s(

.clk_in(clk_in),
.reset(reset),
.h_sync(h_sync),
.v_sync(v_sync),
.h_count(h_count),
.v_count(v_count),

.display_en(display_en) // '1' => pixel region

);

LFSR random_s(

.clock(clk_in),
.reset(reset),
.half_sec_pulse(half_sec),
.rnd_0(random_number_0),
.rnd_1(random_number_1),
.rnd_2(random_number_2),
.rnd_3(random_number_3),
.rnd_4(random_number_4),
.rnd_5(random_number_5),
.rnd_6(random_number_6),
.rnd_7(random_number_7),
.rnd_8(random_number_8),
.rnd_9(random_number_9)
);

sine_wave_gen sine_wave_s(
.clk(clk_in),
.data_out(sine_wave)
);

tempo tempo_s(
.clk(clk_in),
.half_sec_pulse(half_sec)
);

endmodule

set_io v_sync 97
set_io h_sync 76
set_io clk_in 49
set_io reset 66

set_io r_out[0] 91
set_io r_out[1] 95
set_io r_out[2] 96

set_io g_out[0] 75
set_io g_out[1] 74
set_io g_out[2] 73

set_io b_out[0] 87
set_io b_out[1] 88
set_io b_out[2] 90

set_io key[0] 37
set_io key[1] 38
set_io key[2] 39
set_io key[3] 41
set_io key[4] 42
set_io key[5] 43
set_io key[6] 44
set_io key[7] 45
set_io key[8] 47
set_io led_red 23
set_io led_green 24
set_io adc_in 56

FPGA SRAM board

Shadertoy is the future of this project, so what am I doing ? This new board is a reprogrammable FPGA 2D pixel shader (aka fragment shader) which can control the color of pixels and know only of the coordinate of the pixel being drawn. Pixel shaders can also sample the values of nearby pixels. As a result, they can do 2D post-processing (https://en.wikipedia.org/wiki/Video_post-processing) or filtering for a video streams. Why do this on an FPGA rather than in-brower ? You are super low level, and you have constraints based on the number of LUTs, it has a live-playable interface. In any case, I think this is my last board for a while, unless I can make an AI board somehow.

On the other hand, I’m not sure how profound it is to make photoshop like filters. (You can test a 5×5 grid if you go under Filters>Custom in PS). They are all kind of superficial…

I am starting to realize that I spend loads of time debugging soldering errors (yes, I get the learning that comes with that but still). If I made boards and had them assembled elsewhere I would not have this issue. Should I also, in the same spirit, just jump ahead to what everyone else is doing, with the thinking that they are not wasting time on problems that have already been solved and are exploring an interesting space.

I also spend a lot of time designing and building boards, interfaces, and less time programming them: the SCARA robot arm that I didn’t even plug in, the covid temperature interface board, the drone, and the MIT version of the mini swarm robot. On the other side are the projects I’ve perhaps spent too must time making and incrementally remaking perhaps : 3105 power harvester + radio transciever, the Ben Eater style memory. A nice balance was perhaps the solar sunflower protytpes which were experiments with form and function.

*EDIT* I am now thinking that I must work on things that would be of interest to other people, like Machine Learning for instance. I must be humble, just because something is interesting to me doesn’t mean anyone else cares ! Turns our that FPGAs consume a lot less current than GPUs so they are not bad for implementing ML once the training is done. Here is a info about ML with FPGAs :

• https://www.youtube.com/@marcowinzker3682
• https://www.mdpi.com/2076-3417/12/1/89
• https://github.com/verimake-team/MLonFPGA
• https://qengineering.eu/deep-learning-with-fpga-aka-bnn.html
• https://qengineering.eu/embedded-vision.html#FPGA_stitching

Great post about the marble machine project : https://www.reddit.com/r/MarbleMachineX/comments/pzh5kw/an_open_letter_to_martin_on_the_state_of_the/

• The machine is not about reliability and precision, it is about imperfection and the journey
• It’s an art project, it is a project for the project’s sake and the documentation.
• The project shouldn’t run like a start-up, and we are not the sum of what we produce for capitalism
• Not specializing in one thing is what makes this project cool.

ERRATA :

• I think the 590 is not clock dividing as expected…Is it not 3.3V compatible ? I think so, even though unclear on Mouser website.
• Currently only 2 bits of each raspberry pi color input are appearing despite having selected dpi24 in the rpi config file.
• The fine pots are the wrong footprint for the pots I have.
• I could have used DEN (display enable) from the raspi.
• sometimes the rpi starts up and then restarts after playing only a few seconds of video…not sure why.

To change the PLL, there is a tool in IceCube2 under Tool>Configure>Configure PLL Module

Here is the user guide explaining how to use it : https://www.latticesemi.com/-/media/LatticeSemi/Documents/ApplicationNotes/IK2/FPGA-TN-02052-1-4-iCE40-sysCLOCK-PLL-Design-User-Guide.ashx?document_id=47778

I want the following options :

• General Purpose I/O Pad or Core Logic
• Using a feedback path internal to the PLL
• Input Frequency (MHz) : 100
• Output Frequency (MHz) : 25
  

Here is the new PCF file :

set_io v_sync 87
set_io h_sync 88
set_io clk_in 64
set_io reset 66
set_io r0 81
set_io r1 80
set_io r2 79
set_io g0 94
set_io g1 93
set_io g2 91
set_io b0 76
set_io b1 75
set_io b2 74
set_io led 45
set_io locked_led 37

I made a pcf to go with this test code :

set_io R7IN 107
set_io R6IN 106
set_io R5IN 105
set_io R4IN 104
set_io G7IN 97
set_io G6IN 96
set_io G5IN 95
set_io G4IN 112
set_io B7IN 102
set_io B6IN 101
set_io B5IN 99
set_io B4IN 98
set_io R7OUT 81
set_io R6OUT 80
set_io R5OUT 79
set_io R4OUT 78
set_io G7OUT 94
set_io G6OUT 93
set_io G5OUT 91
set_io G4OUT 90
set_io B7OUT 76
set_io B6OUT 75
set_io B5OUT 74
set_io B4OUT 73

set_io v_sync 87
set_io h_sync 88
set_io clk_in 64
set_io reset 66
set_io r0 81
set_io r1 80
set_io r2 79
set_io g0 94
set_io g1 93
set_io g2 91
set_io b0 76
set_io b1 75
set_io b2 74

set_io io0 1
set_io io1 2
set_io io2 3
set_io io3 4
set_io io4 122
set_io io5 121
set_io io6 120
set_io io7 119

set_io a0 138
set_io a1 139
set_io a2 141
set_io a3 142
set_io a4 143
set_io a5 8
set_io a6 9
set_io a7 10
set_io a8 11
set_io a9 12
set_io a10 136
set_io a11 135
set_io a12 134
set_io a13 129
set_io a14 128
set_io a15 117
set_io a16 116
set_io a17 115
set_io a18 114
set_io a19 137
set_io a20 113

set_io cs1 71
set_io we0 7

Here are some images of what a new device could look like !

What about an FPGA chip holder ? And a snazzy pivotable SD card holder ? Using meanders this time? With its own fictional programming language like in that assembly video game ? With a mini PCI-E connector somewhere ?

To pre-digest the videos for the FPGA before putting them on a gigantic SD card, I could use ffmpeg to output a less compressed format like .avi or an .mkv and then erase the header and footer ?

Have a name (little Lebowski urban achiever is too long), and a format 100×80 (free Eagle max), and a rough layout (HDMI super close, USB next to FTDI and to flash memory, all the memory to the right equidistant to the chip). AND, some kind of transparent cover, a first for me, make it seem more like a legitimate product and would reduce the risk of short circuits from something conductive falling on the board. For the symbols on the keyboard, there is the Comodore 64 keyboard symbol set which is cool. Or some ancient symbols ??

I am now moving away from SDRAM, challenging and I’m not sure why I’m putting myself through it. The real interest is going to be decoding videos stored on the SD card and putting them on screen. I want to try to do it like the pros – drawing to the screen in the blanking period and using only one SRAM.

****

Still trying to resolve the A18 issue.

• I tried soldering another IO pin to pin 20, but this led to total chaos, none of the address pins working. I could have tried severing the link between the pin 20 and the SRAM but I don’t want to damage the board before I identify the problem (it may be in the code?).
• Trying to lower the size of the address counter to stop at 17 instead of going to 18.
• I connected to the rpi’s DEN and changed the code to work with it instead of the FPGAs display en (it doesn’t work anyways). It is cool as it is more likely to capture the image on the rpi if I understand correctly.

****

I am now trying some of the code I was dreaming about – modifying the input and output video stream based on other parallel data.

Here is one strategy based on two bits of the same color having an impact on recording and playback.

if (b[3]==b[2]) begin
a <= data_in;
end
else begin
a <= 8'b00000000;
end

I have the two memories working (excepted A18 on the second SRAM), and also tried reading DEN from the rpi. It makes some pretty funky glitches by touching the RAM pins with my hands !

Also check out the bitmap to program the FPGA :

`default_nettype none

module vga_sync_test(

input wire clk_in,
input wire reset,

input wire rec, // Direction of io, 1 = set output, 0 = read input

//RASPBERRY PI
input wire [3:0] r_in,
input wire [3:0] b_in,
input wire [3:0] g_in,
input wire DEN,

//VGA OUT
output reg [3:0] r_out,
output reg [3:0] b_out,
output reg [3:0] g_out,

output wire h_sync,
output wire v_sync,

//SRAM

output reg [20:0] addr,
output reg [20:0] addr_copy,
inout wire [15:0] io, // inout must be type wire

output wire cs_3,
output wire cs_2,
output wire cs_1,
output wire cs_0,

output reg we_1,
output reg we_0

);

wire [15:0] data_in;
wire [15:0] data_out;

reg [1:0] toggle;

reg [15:0] a, b;

assign io = rec ? a : 16'bzzzzzzzzzzzzzzzz;

assign data_out = b;

assign data_in[1:0] = DEN ? r_in[3:2] : 0;
assign data_in[3:2] = DEN ? b_in[3:2] : 0;
assign data_in[5:4] = DEN ? g_in[3:2] : 0;
assign data_in[7:6] = 2'b00;

assign data_in[9:8] = DEN ? r_in[3:2] : 0;
assign data_in[11:10] = DEN ? b_in[3:2] : 0;
assign data_in[13:12] = DEN ? g_in[3:2] : 0;
assign data_in[15:14] = 2'b00;

wire display_en;
wire [11:0] h_count;
wire [11:0] v_count;

localparam h_pixel_max = 1280;
localparam v_pixel_max = 960;
localparam h_pixel_half = 640;
localparam v_pixel_half = 480;

// CS: low to select, high to deselect

assign cs_0 = toggle == 2'b00 ? 1 : 0;
assign cs_1 = toggle == 2'b01 ? 1 : 0;
assign cs_2 = toggle == 2'b10 ? 1 : 0;
assign cs_3 = toggle == 2'b11 ? 1 : 0;

//SRAM address counter

always @(posedge clk_in) begin

if (addr == 0) begin
   toggle <= toggle+1;
end

if (reset) begin
   addr <= 0;
end else begin
   addr <= addr+1;
   addr_copy <= addr_copy+1;

end
end

//REC control

always @(posedge clk_in) begin

   b <= io;
   a <= data_in;
if (rec) begin
   we_0 <= addr[0]; //not sure why it isn't the inverse of addr[0] but that doesn't make the inverse on 'scope
   we_1 <= addr[0];
end
else begin
   we_0 <= 1;
   we_1 <= 1;
end
end

//VGA COLOR OUT

always @(posedge clk_in) begin
if (DEN) begin
if (toggle==2'b00 || toggle==2'b01 ) begin
   r_out[3:2] <= data_out[1:0];
   r_out[1:0] <= data_out[1:0];
   g_out[3:2] <= data_out[3:2];
   g_out[1:0] <= data_out[3:2];
   b_out[3:2] <= data_out[5:4];
   b_out[1:0] <= data_out[5:4];

end else begin
   r_out[3:2]<= data_out[9:8];
   r_out[1:0]<= data_out[9:8];
   g_out[3:2]<= data_out[11:10];
   g_out[1:0]<= data_out[11:10];
   b_out[3:2]<= data_out[13:12];
   b_out[1:0]<= data_out[13:12];
end
end else begin
   r_out <= 4'b0000;
   g_out <= 4'b0000;
   b_out <= 4'b0000;
end
end

vga_sync vga_s(
.clk_in(clk_in),
.reset(reset),
.h_sync(h_sync),
.v_sync(v_sync),
.h_count(h_count),
.v_count(v_count),
.display_en(display_en) // '1' => pixel region
);

endmodule

From https://www.fpga4fun.com/VerilogTips.html:

• I need to initialize verilog counters !!
• Another way of selecting 4 bits in a vector : wire [3:0] thisis4also = myvalue[16+:4];
• It might be smarter to use a PLL than to take the external clock directly.
• I need to debounce all input buttons !

****

Check out shaders that take video as input :

https://www.shadertoy.com/view/ctsyzN

https://www.shadertoy.com/view/XtcSRs

****

Tried to make some vignettes of the new board to show the impedence matching :

I think I will order it in white with the meanders exposed like on the VGA spaghettini.

Color options (I’m leaning towards white or maybe green):

***************************

I am now thinking about how I will be able to share all that I am trying to learn about verilog and FPGAs in workshops. The bottleneck is programming the FPGA without special hardware.

OLIMEX has a link to a rasberry pi utility called flashrom that can program and read FLASH memory documented here : https://github.com/OLIMEX/iCE40HX1K-EVB/tree/master/programmer/olimexino-32u4%20firmware

These raspberry pi examples program the ice40 and looks simple :

• https://j-marjanovic.io/lattice-ice40-configuration-using-raspberry-pi.html
• https://github.com/plex1/raspice40

The steps have been automated here : https://notabug.org/sagaracharya/swarajya/src/master/hdl_to_hx8k/on_pi

Also for the rpi Pico : https://github.com/dan-rodrigues/pico-hx

I could knock off the 2232 FTDI and have made something like this: https://shop.trenz-electronic.de/en/TEM0009-02-FPGA-USB-programmer-JTAG-for-development-with-Microchip-FPGAs

Most interestingly, it seems like Arduino Uno could program an FPGA using a library like SPIMemory by Prajwal Bhattaram : https://github.com/Marzogh/SPIMemory/tree/v2.2.0

Finally, I could make a board like the gameduino that has an API for the Arduino to use to talk to the FPGA which handles fast screen drawing. This would mean everything could be done within the Arduino IDE.

EDIT* Come to think of it, even if the FTDI adds cost, it would make everything so much easier for a workshop – one piece of software and no extra hardware to program after for the participants. But when I plug it in it says USB device malfunctioned…(I also realized that I think I can forgo the RS232 connections between the FTDI and the FPGA and just connect it to the EEPROM and FLASH.)

EDIT* The OLIMEX code for Arduino is also not compiling and winIceProgDuino.exe (to program FPGA by sending serial commands to Arduino firmware I suppose) is not opening either.

EDIT*2 The Arduino sketch compiles but only for MEGA, Leonardo, and Micro so far (no UNO or NANO or MINI) but only after removing the iceprog.cpp file.

******************

Some thoughts on low-level versus high-level programming :

Something unsatisfying about making something from a pre-digested meta language (fast.ai for instance). Lost the feeling of ownership of the thing you’re making.

• https://projectf.io/posts/fpga-graphics/
• https://github.com/lawrie/hdmi_examples/tree/master

I have a month to work on a 45 minute lecture on my work at the Technische Universität München. I will also be doing a lecture at TU Darmstadt in November. I would like to use this opportunity to try to bring my video experiments into focus and incorporate it into my previous time-lapse projects.

This could take the form of a video series of me playing the prepared video buffer, possibly with explanations about what is causing what effect and demonstrative images / videos ? It could be contrasted with a “typical” workflow using the constraints of a software platform like photoshop? I could prepare this a similarly focused investigation of how the prepared piano altered sound, how Sonia Sheridan altered the photocopier, Paul Schafer made custom concrete music machines, etc.

EDIT* : I had a try !

• It’s kind of long and I also need to get a better top view.
• Adding text to describe what’s happening ?
• I also see that when I’m turning knobs the device is kind of hidden. I haven’t really designed the interface to be playable and to look good and be legible while being played.
• Looked into some other examples of video synth top down videos :

This is making me think more about the physical presence of my devices, and how I could incorporate more mechanical parts – instead of purely making electronics. I may have to play the game a bit more, make things that look like what they do and help people understand the associations I’m trying to make.

I could have micrometer heads for the potentiometers :

I could have fiber optic cables too :

I think if I every try to make a product though I would need to team up with someone who has skills I don’t.

***

Why make hardware ?

• it can be analog and digital
• it’s faster at doing things with video than software
• it can be custom
• it has a live-playable interface

***

What effects am I creating ? (check out Premiere to see what kinds of effects exist).

• Recording and playing things back at different speeds (video transposition), assigning to different color channels
• desynchronizing recordings with the screen sync so that they jump around
• recording videos side by side in memory so that they bleed over one another.
• Video collage and montage composer (video sampling, video looping), video plastifier, étude II, micro-montage, noise research, play, do and see, polyvideo layering, defamiliarizing of the image + reflecting the mediascape we inhabit, video as “palpable”, “nontheoretical”, and “experiential” (quotes from musique concrete wiki).
• The structure of the videos is based on the indexicality of the medium (the SRAM and how it stores). So the recording technique is also the synthesis technique.

Struggling to represent the painterliness of the raster videos without showing them as a video. It is completely different from my experiments with lines and triangles, and is less intuitive for me. An attempt at a kind of chronogram of a video :

It gives some idea of the range of images I guess?

Here are some notes I took about a year ago after visiting a painting expo that relate to my painterly video experiments :

• Layering
• Contour
• Surface
• Saturation
• Flow vs. Choppiness
• Roughness, relief 
• Edges versus centers
• Movement vs stasis 
• Enriching of detail
• Abstracting, cosmic making
• Fine lines versus coarse
• Exposure 
• Color fields
• Texture
• Deep friedness
• Films of cows, ocean. Stills of still life? Flowers, birds, drapes folding, mold, fruit, bones
• Color mixing vs melting vs meeting
• Paint viscosity (runny vs clotted)
• Direction of brush strokes 
• Contour
• Focus direction in canvas
• Translucent flesh, shine vs glow from interior, waxiness 
• Graininess 
• Composition, color pairings and form
• Foreground displaced to background vice versa 
• Meeting pattern planes 
• Lighting and shadow
• Illusion of depth
• Cloudiness 
• Turbulence

Check out this “glitch” video artist Jacques Perconte that Marc shared with me : https://www.youtube.com/watch?v=8_Xhu9Vx5XM

He works, since the 1990s, with compression and achieves a painterly, impressionistic effects and exposes them on immense projection surfaces.

Check out also Tauba Auerbach’s work :

Jack Whitten :

*************

Some quotes from Art21 series :

James Turrel – what you are perceiving is perception itself. We don’t receive the world around us we create it.

Jeff Wall – Art gives you an experience that alters something, it doesn’t tell you or convince you.

Jeff Wall – When I started photography there were potential energies in the medium that weren’t being realized.

Roland Barthes – The punctum points to those features of a photograph that seem to produce or convey a meaning without invoking any recognizable symbolic system.

Olafur Eliasson – Art provokes a negotiation : why I am seeing this the way that I am seeing it, what does looking mean? Instead of questioning the object you are questioning yourself. Art offers the opportunity for self-evaluation.

Tauba Auerbach – I want to learn things all the time, I want to understand the patterns behind things. I experience science through craft. With craft I try to cultivate sensitivity in a practiced, purposeful way. If you work with marbling you know just as much about viscosity and flow than a scientist, through your fingertips in a different way.

Tauba Auerbach – Ideally I want to make an image that has a tiny effect on all the future images that you see.

Tauba Auerbach – The pursuit of the sweet spot, cultivate the place of boundaries, limits of fraying, not hard edges.

Cindy Sherman – I don’t know what I’m looking for until I see it.

Richard Serra – Artists invent strategies, tools, techniques, that allow themselves to see in a way they haven’t seen before to extend their vision beyond the standardized classic reflex actions. These help us to see inside what we’re doing so we don’t get into a lock step notion of how to do what you do.

Louise Despont – If you’re always making work for someone, and not for yourself, maybe you don’t let yourself make the mistakes that are necessary.

Louise Despont – Each drawing is a series of tiny discoveries, it reveals/unfolds the drawing from total control. I own at most 1/4 of the drawing. The rest is something else, this is what’s exciting.

Louise Despont – It’s best explained in the drawings, words are clumsy to describe something like the concrete feeling of spirituality.

Liz Magor – My Studio is a space to reconcile dissonance, no one knows I’m here. When I’m not in my studio I want to be in my studio working. My tools are rudimentary. I’m here for pleasure but it’s not fun. Everyone should have a studio for mental health. I can filter out the noise and see the ever present under the radar stuff.

Liz Magor – I’m not an animist but objects have stuff in them that comes out. I try to resurrect these objects from the netherworld.

Liz Magor – The slowness of the material process matches the slowness of my thinking process.

Liz Magor – I’m creating an experience for looking.

Liz Magor – I give myself my own program, I give myself my own assignments. And art is the choices I make.

Liz Magor – Maintaining the conditions for this production, which is not very logical, uncalled for. No one is asking me to do this, I’m barely asking me to do this. To do this I have to overlook my making with the journey of the things into the world.

Liz Magor – After the casting I unwrap it like a little gift, there are surprises.

Elliott Hundley – This photoshoot is so elaborate but not because I want a certain effect, because I want to not control the effects, and have a layer of unexpected results. In relinquishing control, the piece gives me something back I didn’t expect.

Jack Whitten – I’m not a narrative painter.

Jack Whitten – I built a device to move large amounts of acrylic paint in one gesture.

Katherina Gross – Painting is not linear. The synchronicity in painting is compelling for your thought process. I’m trying to grasp some of those fast thoughts that are moving through my brain.

*************

Reading about the history of video synthesis.

From https://museumzero.blogspot.com/2013/12/its-all-baseball-nam-june-paik-starts.html)

Nam June Paik sees Taoist energy in working with the flow of TV video :

“To receive simultaneously the parallel flows of many independent movements is, as Paik pointed out at the time, a classical Taoist way of meditating: by becoming aware of everything going on in the present, you discover eternity right now.” 

“I love Chinese history, surprise, nonlinearity.  You know what judo means?  A way to be soft.  You let other guy do all the work.  I think in some Oriental way.  In TV I try not to be boss, to stay as small as possible.  So that seems to work. “ 

“So then when I started TV, the best decision I made in life is not really to go into TV, but to do work inside TV.”

“Imagine everything that exists is flowing, like the tao, in a perpetual motion, with endless waves, like the ocean.  We come from it; we go back to it.  Whatever surges forward falls back, so Lao-tse, who wrote the Tao Te Ching (On the Nature of the Way), urges us not to try too hard.  Relax; be like a baby; follow whatever path presents itself.  That is the way. ”

Not striving to fit yourself to some preconceived ideal, like a Buddhist or a Confucian; simply being, following breath wherever it blows.  In this sense, the television signal is like the tao; endlessly variable, continually reversing itself, dying, being reborn, it is never idle, yet it is so vast and perpetual that it often seems calm as the sea.

Beginning with whatever live programs came along, distorting them, then recombining his distortions like waves on the ocean surface, Paik created an indeterminate and endless show for the Galerie Parnass, in Wuppertal, Germany, in 1963.  

From Scanimate: The Origins of Computer Motion Graphics :

• This is about the history of television, these were the first ways to put text and make graphics on screen (Media Archaeology!). Nowadays visuals are gratuitous. What did we lose in the transition to digital ? The imperfections, the proximity to the functioning.
• Had a role in music videos, and news segments, so was part of culture.
• “Blooming” is the term for the glowing edges in CRT Scanimate.
• It’s real life artefacts. It’s like exploding scale models instead of GCI.
• They made cookbooks with the recipes of different effects that created while working with clients.

From https://wearethemutants.com/2018/01/09/a-sloppy-machine-like-me-the-history-of-video-synthesizers/

Like its close temporal and conceptual counterpart, the audio synthesizer, the video synthesizer was created iteratively by academics, artists, and tinkerers, then eagerly snatched up by the world’s biggest media producers once prototypes had proved their power and versatility.

• Started with experimental musicians like John Cage and la musique concrète.
• Early pirate TV station in NYC.
• Amiga supplants the Scanimate and analog synths.
• The 1967 Portapak release and it’s importance for activism and experimental art.
• Video comes from the root video of Latin video (“I see”).
• There is a relationship between images and waves  :

CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=641492

This is so hard for me to understand but this somehow relates to chirping also :

By Drummyfish – Own work, CC0, https://commons.wikimedia.org/w/index.php?curid=77608151

More cool matrix math image modifications here : https://en.wikipedia.org/wiki/Digital_image_processing

Also this website which describes it all visually ! https://setosa.io/ev/image-kernels/

From Video Art : An Anthology :

• • The synthesizer let’s you see things that exist only in the mind’s eye.
  • visual ingredients
  • video synthesizers churn out…images based on their own electronic structure.
  • We make the image with our eyes and brain. It’s psycho-visual
  • video as concretized imagination.
  • video is surreal, the images are ephemeral products of micro electronic pulses.
  • “electronic imagery”
  • video is a medium which works with time

The Vasulkas

*************

Here is an attempt to describe what could be a model of a potential “practice” :

*EDIT* This should include me blogging ! Maybe add a RESEARCH and/or DOCUMENTATION phase ?

*******

Check out this pyramid of types of work :

I feel like my project is about analysing (and curating), I’m not sure if I take a real position.

*******

Check out this amazing NIME article called The Concentric Sampler: A musical instrument from a repurposed floppy disk drive by Timothy Tate about “the redundancy and physicality of magnetic recording media” which utilizes “time-based granular synthesis” and lo-fi:

https://nime.pubpub.org/pub/uh76shf0/release/1

Some quotes :

• Physical media offer an opportunity to “foreground the physical medium as a tool for musical expression.”
• “The deterioration of old magnetic tape as it is looped, defining a … musical structure.” The “failure of the medium is in focus, rather than the mechanism.”
• “as soon as something’s on tape, it becomes a substance which is malleable and mutable and cuttable and reversible in ways that discs aren’t.”
• “This study emphasises working within a medium’s limitation, rather than prescribing a compositional framework or sonic agenda upon it”
• Motivation to “foreground musical and technical possibilities…and generative sonic potentials…and novel, unique expressive and
• compositional possibilities”…to be “discovered…explored”
• The device is a “performable instrument and a generative sonic tool”
• “Rather than focusing on the authenticity of the sound reproduction, the Concentric Sampler draws focus to the byproducts and the resultant indexicality and generative sonic possibilities of the floppy disk as a medium.”
• “the term ‘musical expression’ here places value on the ability to shape and define a musical grammar from the indexicality of the …medium and mechanism.”
• “subverting traditional modes of … expression“
• “Each section is accompanied by a demonstrative video” !!!
• The live playable instrument can “achieve the dissociation of pitch and time“
• “imperfections in … reproduction”

• “possibilities within a framework of … making”

Now following up on some of the references from this article:

• You can think of an instrument as a framework that has a predisposed range (affordances). Our tools provide a certain range of suggested usages. Some things are easier and some things harder to do with an instrument, this is the instrument’s spectrum. If you stay within those ranges, you accept the silent grain of the instrument. If you make an unusual tool then, do you risk finding yourself in an unusual affordance ? (J. Mooney) Could it be possible to make videos subtractively, instead of additively ?
• From New Media Reader : The different between representation and simulation. P.18″Digital media process the physical properties of the input data, light and sound waves, are not converted into another object but into numbers; that is, into abstract symlbols rather than analogous objects and physical surfaces. Hence, media processes are brought into the symbolic realm of math rather than physics or chemistry. Once coded numerically, the input data in a digital media production can immediately be subjected to the math processes of addition, subtraction, multiplication and division…” AND compressed AND manipulated more easily than analogue forms because they are more mutable than objects. Also easy access and quick movement of the data of an enormous mass of data. This causes the materiality of the world around us to become unsteady…The televisual
• Because everything else is also digitized, there is a “convergence of previously discreet media forms, now a new fluid area of media decentralized production and consumption. Remediation, Multilinearity.
• Hand-made videos. Exploring the boundary between hand tools and large-scale machines which is a distinction Marx makes P.91.

Check out these Bauhaus era artist’s work with the audio band in video :

Paul Schaeffer (coiner of the “club d’essai“) designed specific tools like the morphophone and phonogène for modifying audio for musique concrete :

*******

Watching ENSCI diploma presentations I’ve thought about how nice the sequence is : first you write something that explores a topic and cites thinkers on the subject, and then you work on a design project that relates to this somehow. Also looking back at some videos, there is already a lot of content I have produced that I could try to learn from ! Like that Amsterdam-based artist told me, I could also focus on using my tools.

I am also doing a synth workshop in late September at Villette Makerz but I’m not sure if I can connect to that or not here. *EDIT* an FPGA board that generates patterns based on audio input is a GO !*

I also want to make a next FPGA board which will be a software reconfigurable device so that I can move to verilog for the summer instead of making a new board for every experiment. Not sure if this could also take the form of a simple video synth for Villette Makerz or at least a simplified version perhaps.

*******

Some quick looking in to GPUs :

GPUs are all about direct memory access (DMA) not mediated through the CPU. A thought about the FPGA board – perhaps I should first have Arduino mess with the clock while playing back / recording something on the 16MB board (but I’m limited to the number of pins for address and I/O – it would essentially be a counter that could change in frequency on the fly)? Having memory connected to the screen (a screen buffer) and modifying it is the fundamental computer display setup. From 1951 a memory pattern on CRT :

It would be cool to experiment with sprites and copying parts of memory from one bank to another too like a blitter https://en.wikipedia.org/wiki/Blitter .

It looks like what makes shaders cool is that they are programmable and have their own code languages now. Before shaders there were hardware rendering pipelines called fixed-function. Different units would be responsible for specific functions. It seems like these units would take in vertex data then output pixel colors.

I looked in to how to do matrix multiplication in hardware. It actually seems to be more natural as an analog circuit with resistor arrays. It can also be done by multiplying two 2-bit binary numbers using this kind of logic setup :

**********

I am becoming more and more curious about the difference from having a screen buffer that is written to during the blanking period and having a massive bank of memory that can be recorded to like in the 128Kbit. Check out these articles about how writing and reading to video memory is dealt with in different systems :

https://en.wikipedia.org/wiki/Tiled_rendering

https://en.wikipedia.org/wiki/Multiple_buffering

https://en.wikipedia.org/wiki/Vertical_blank_interrupt ,quoted from : 

“During the vertical blanking interval, the driver orders the video card to either rapidly copy the off-screen graphics area into the active display area (double buffering), or treat both memory areas as displayable, and simply switch back and forth between them (page flipping). [The two buffers are called the front and the back buffer] Some graphics systems let the software perform its memory accesses so that they stay at the same time point relative to the display hardware’s refresh cycle, known as raster interrupt or racing the beam.” [i.e. you can also draw things during the horizontal blanking interval]

**********

The Real-Time Corrupter is fascinating https://redscientist.com/rtc . The kinds of memory modifications it allows for are fascinating and far more dynamic than static, text-based find-and-replace experiments I’ve done in workshops. Looking at this video I learned some cool stuff (https://www.youtube.com/watch?v=n9HS6zftuSk&list=PLItZ3jvJKD7rnoxmqJJ0B5E1B9_WW9L5E&index=2). For instance, copying values from one address (in video RAM, scrolling backdrops memory space a.k.a. “nametables”, NES RAM, ROM etc.) and then reapplying them to another address every frame (called piping) or just one time, the ability to isolate specific effects with the sanitize function. It can generate noise between certain values, or shift values up or down on (called tilting), listen to a value and then reapply it after a fixed number of frames, freezing the current value somewhere for future frames, replacing values intelligently with values in certain sets (for 3D glitching). It’s like performing brain surgery while the patient is fully conscious and telling a story. All of these memory transformations could be applied with the FPGA board !

**********

In a similar spirit, this game called Code War involves creating a program that competes with others to write to all of the memory space. There are competing strategies (quoted from https://corewar-docs.readthedocs.io/en/latest/corewar/strategies/) for warriors :

Rock - a warrior which rapidly bombs the core with dat instructions
Paper - a warrior which replicates, creating multiple, parallel copies
Scissors - a warrior which scans the core looking for other warriors

The battle is visualized in a memory grid (https://corewar-docs.readthedocs.io/en/latest/corewar/visualisation/)

You can simulate and battle warrior code here : https://crypto.stanford.edu/~blynn/play/redcode.html

**********

Visualizing memory access in time. From https://bling.kapsi.fi/blog/x86-memory-access-visualization.html:

*********

Some thoughts on HCI from people at work :

it’s research if it follows scientific method and has possible applications.

Find your peers, try to publish in their journals.

The idea of publishing is to get feedback from your peers.

If you make a pedagogical tool, then you could test how effective it is at helping people learn.

Based on this conversation, I thought about how I don’t necessarily want to promote engineering education and that I always want to be on the design/art side of things. I also have learned that I find doing something I already know how to do less exciting, and so making simple kits or small series of artworks that are guaranteed to work for days on end, is not always super rewarding for me intellectually. This leads me to the current conclusion : I want to teach and then do a kind of artistic research on the side. I should then keep building my teaching career and try to get expos of my work. I am still trying to figure out how exactly my artistic research should be communicated (through articles in design magazines, through conferences with expos connected to them?).

**********

I am preparing a solar workshop at Villette Makerz based on the simple solar engine with optimized SMD components. The idea is an art bot that will draw, paint, in the sun. I am working on testing the various combinations of solar panels, capacitors and voltage supervisors.

We are also making a version 2 of the video synth modules which are all Eurorack compatible in terms of dimensions, use 3.5mm audio jacks, the eurorack power supply. The idea is that the modules be both manual and automatable for the purpose of demos and to be didactic for students learning about analog electronics.

Marc is doing a great job reimagining this project – he is good at compromising and imposing the vision of the final thing on each step of the construction. I am, in contrast, driven astray I think by my fascination by what “the machine itself wants to express”…

********

Finally getting around to testing the Arduino-controllable analog switch to activate record or READ mode on the SRAM 16MB board. The idea is to test taking a recorded video and then doing some bit manipulations with it and saving it back to the memory. Predictably though, I’m having issues just writing anything to the thing…

I/O pins on Arduino 0-7
CLK on Arduino 12
REC on Arduino 13 connected to analog switch connecting the WR pin on SRAM to either VCC or !CLK

unsigned long memory; //total number of 8bit words on the 16Mb SRAM = 2048000

const byte IO_0 = 7; 
const byte IO_1 = 6; 
const byte IO_2 = 5; 
const byte IO_3 = 4; 
const byte IO_4 = 3; 
const byte IO_5 = 2; 
const byte IO_6 = 1; 
const byte IO_7 = 0; 

void setup() {
//Serial.begin(115200);
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);

pinMode(IO_0, OUTPUT);
pinMode(IO_1, OUTPUT);
pinMode(IO_2, OUTPUT);
pinMode(IO_3, OUTPUT);
pinMode(IO_4, OUTPUT);
pinMode(IO_5, OUTPUT);
pinMode(IO_6, OUTPUT);
pinMode(IO_7, OUTPUT);

//WRITE
while(memory<= 2048000){
memory++;

// if (memory%10000==0){
// Serial.println(memory);
// }

if (memory%5==0){
PORTD = B11110000; // the IO pins. simple pattern test.

}
else{
PORTD = B00001111;// the IO pins. simple pattern test.
}
//WRITE MODE
PORTB = B11101111; // PIN 12 ARDUINO CLK goes LOW/HIGH
PORTB = B11111111; // PIN 13 ARDUINO WR STAYS HIGH

}
// Serial.println("finished writing");
}

void loop() {
pinMode(IO_0, INPUT);
pinMode(IO_1, INPUT);
pinMode(IO_2, INPUT);
pinMode(IO_3, INPUT);
pinMode(IO_4, INPUT);
pinMode(IO_5, INPUT);
pinMode(IO_6, INPUT);
pinMode(IO_7, INPUT);

digitalWrite(IO_0, LOW);
digitalWrite(IO_1, LOW);
digitalWrite(IO_2, LOW);
digitalWrite(IO_3, LOW);
digitalWrite(IO_4, LOW);
digitalWrite(IO_5, LOW);
digitalWrite(IO_6, LOW);
digitalWrite(IO_7, LOW);

//PIN 13 REC IN LOW READ MODE
PORTB = B11011111; // PIN 12 ARDUINO CLK goes LOW/HIGH
PORTB = B11001111; // PIN 12 ARDUINO CLK goes LOW/HIGH
}

unsigned long memory; //total number of 8bit words = 2048000
byte cell; // store the word at this address

void setup() {

//PD0 - PD7 are IO
pinMode(13, OUTPUT); // REC - PB5
pinMode(12, OUTPUT);// CLK - PB4

 while(memory<= 2048000){
    memory++;
//READ
        DDRD = B00000000; // all IOs in INPUT
        PORTD = B00000000; // no pull-ups

        PORTB = B11011111; // WR stays LOW + CLK HIGH
        delayMicroseconds(10);
        cell = PIND; // read the cell at this memory address and store it in the variable cell
        delayMicroseconds(10);
        PORTB = B11001111; // WR stays LOW + CLK LOW
        delayMicroseconds(10);

//WRITE
       
        DDRD = B11111111; // all IOs in OUTPUT

        PORTD = ~cell; // write  a transformed cell back to memory
        PORTB = B11111111; // WR stays HIGH + CLK HIGH
        delayMicroseconds(10);
        PORTB = B11101111; // WR stays HIGH + CLK goes LOW
        delayMicroseconds(10);
  }
}


void loop() {
//READ MODE TO SEE WHAT WE HAVE IN MEMORY
        PORTB = B11011111; // WR stays LOW + CLK HIGH
        delay(500);
        PORTB = B11001111; //  WR stays LOW +  CLK LOW
        delay(500);
}
Not working either...

Heading towards a more reliable, deployable and software-leaning approach (but not so much about automated choreography as with previous atmega boards as augmented live playable machine for manual performances) to working with video now.

I am also trying to be a bit more strategic and attempt to think ahead a little bit beyond the one board one experiment situation. It takes a long time to trouble shoot a single board and learn all the lessons from it, I have to give each board the time it deserves and I need to be perhaps less productive and more thorough.

I am also coming to the awareness of what is my scope with this next board :

• I won’t be doing challenging engineering things (like implementing different ways of programming the same FPGA, interfacing with differential pair protocols like HDMI) that have no impact on the images and take loads of time to do.
• These are boards for experimenting and live playing, so they also need to have controls on the board.
• I also need to think about safety, avoiding the possibility of easily making short circuits and damaging the board.
• I’d also like to move back to color, and away from the intense limits of exclusively 1bit resolution.
• I want to keep removing superfluous cables and adapters too, this one will have only a VGA out.

I made a map of my prototypes so far for this project :

It’s been around two years I’ve been working on this !

After talking with Zach at work, his idea was to show not just the screen but also me turning knobs etc. Here’s what this could look like :

Or,

…or,

It would be nice to have a computer interfaced oscilloscope to record the signals.

*****

The most plug and play option would appear to already exist : a tiny raspberry pi zero can already run Processing scripts and control small screens https://learn.adafruit.com/processing-on-the-raspberry-pi-and-pitft/processing !

Here’s a good intro to making simple patterns with processing : https://processing.org/examples/

We would be more in the zone of software video synth : https://learn.adafruit.com/feather-rp2040-dvi-video-synth

Also seem to be companies making just this kind of thing : https://store.excamera.com/

Arduino talks to the FPGA by SPI as if it were a RAM space. https://excamera.com/files/gameduino/synth/doc/gen/poster.pdf

Design / Engineer friend Paolo Salvagione pointed me to Configurable mixed-signal ICs. It appears to be like an FPGA but for mixed analog and digital circuitry and is configured in design software.

There is also the world of ASICs and the google open-source silicon project https://developers.google.com/silicon

*************

My project was originally about slowing down computer processes and representing them in space. Now I just seem to order things on Amazon and design increasing numbers of PCBs. It seems that I have so little time to do the art in the end because of how much investment the technical stuff requires. How could I get back to my original project here ?

My project also had a collection of related techniques :

• Try to free machines from their corseted, factory settings and reveal their full range of expression that would otherwise just exist in a parallel unseen dimension
• Try to show our files from the perspective of / through the eyes of the machines that are processing them.
• Curate series of abstract formal compositions which emerge from figurative, architecturally-themed or culturally iconic ones.
• Try to describe the behaviour / idiosyncracies of algorithms and make them tangible
• Isolate specific moments of machine-to-machine interface in a larger system
• Get one’s hands inside the black box, and make prepared machines which expose their parameters
• Try to rebuild electronic systems based on help from the DIY internet and then hope to stumble on something unintentional
• All the while emphasize the materiality of technology
• Trying to go super low-level and avoiding abstract computer “visualizations”
• Exploring the link between visual chaos and harmony, that sweet spot of medium entropy.
• Riffing off of the music synthesizer movement of knobs and playful electronics interfaces and its anti-theory vibe
• Exploring the surreal, bizarre space of the computational unconscious
• Do “artistic research” projects that are educational, at least for me
• play with form versus content

I wonder if the pixel based screen is not really appropriate for my methodology. It’s the opposite of over-looked and black boxed. It’s an obsession for an entire culture. It also does a pretty good job of “representing” what happens inside the computer already. It doesn’t really need my help !

********

I also need to do a debrief on this leg of the video synth project. What have I learned ?

Technical stuff :

• • • How to make and debug PCBs
    • To work with video + SRAM with counters as well as some op amp circuits. The difference between digital and analog in the video context.
    • To work with the VGA protocols, about resolution and brightness of the image.
    • I learned about oscillation, the difference between KHz and MHz in the context of video and what sampling is.

Stuff about media representation

• • • some aspects of the nature of visual memory, how some of our sensory apparatus work at different speeds
    • the curious experience of “searching” for an image (like when messing with ADC knobs and CLK speeds).
    • what is required to identify / recognize and image or scene, how much resolution and shape
    • Deconstructing the illusion of television by interacting with its materiality and mutability
    • Repeating historical art explorations with television (see Sans Soleil – Chris Marker)
    • synchronizing the data with the frame of the image is a key part of the illusion of video. If you mess with this suddenly the video frame becomes a malleable object. If it is desynchronized, the image is out of frame and will jump around with the SRAM recording. If you change the speed of recording or of playback you can zoom.
    • Layering of different images in a palimpsest can create textures from them.
    • I’ve made some nice abstract pattern discoveries through knob twisting.
    • Exploring the gap between legible figurative image and abstract patterns, contours, fields,
    • the texture and grain of data at various scales
    • the connection between video and abstract field painting

What does it mean to be trying to make super simple hardware video filter in the age of AI generated video and images ? How is this activity relevant ? I feel like I’m looking for low hanging fruit here but I’m not sure there is any left. Also, the time it takes to make a single experiment in hardware is astronomical compared to the software option…

I think the project started off about the screen itself, how to send signals and display them. At some point it became clear that the screen just displays data stored in memory.

In this spirit, I could try to represent memory access patterns : https://en.wikipedia.org/wiki/Memory_access_pattern Or the patterns that memory is refreshed in : https://en.wikipedia.org/wiki/Memory_refresh

http://www.overbyte.com.au/misc/Lesson3/CacheFun.html

I could also sample images and then modify them algorithmically? But it kind of ends up looking like simple Photoshop filters. It would have to be modified in some way based on the way the image is stored in the memory ?

Check out this image stored in DDR ram decaying over time from J. Alex Halderman’s paper : https://jhalderm.com/pub/papers/coldboot-sec08.pdf

Also it seems like different DDR has different decay rates (from A Trustworthy Key Generation Prototype Based on DDR3 PUF for Wireless Sensor Networks https://www.researchgate.net/figure/DRAM-cells-decay-feature-with-power-switch-interval-time-of-120-s-a-DDR3-device-1-b_fig3_263586301):

For comparison, check out the same Mona Lisa image sent through the air and damaged by the earth’s atmosphere :

********

I’ve never thought of this before but I guess I could generate a simple arduino code, and then take the .hex file and glitch it with any of the glitching techniques I’ve been using and see what it puts on screen.

I could also test overclocking / overheating the atmel and seeing how they collapse !!

********

I should also finish the boards I’ve already designed and had made, they offer learning opportunities and possible discoveries ! The bucket brigade, the digitally-controlled pots (meh), and the band splitter (*EDIT* completed !) are the three that are left from that series. Also the Palimpsest.OS 2 board when controlled by microchip – especially if I can get the sync working ! Of course I have the new 128Kbit memory board (*EDIT* all done !) once I get the parts too and then a final (?) FPGA v2 board.

********

I am still interested in exploring FPGAs and getting my hands in the tech to possibly stumble on cool stuff though so here is a second attempt at a video FPGA board based on the iCE40HX1K-TQ144 to output HDMI, DVI, VGA, and composite video.

For generating verilog, there is migen for python 3 (https://github.com/m-labs/migen). I’m going to try a super simple thing in Verilog first to get a feeling for it. 

I am learning verilog here : https://hdlbits.01xz.net/wiki/Main_Page

It looks like generating HDMI is doable even though there is a difference between LVDS and TMDS (involving possibly 100nF series capacitors ?) :

Here is the official guide : https://www.latticesemi.com/-/media/LatticeSemi/Documents/ApplicationNotes/UZ/FPGA-TN-02213-1-7-Using-Differential-IO-LVDS-Sub-LVDS-iCE40-LP-HX.ashx?document_id=47960

https://www.fpga4fun.com/HDMI.html

blackmesalabs.wordpress.com/2017/12/15/bml-hdmi-video-for-fpgas-over-pmod/

https://github.com/hdl-util/hdmi/

Different chips being used like the PTN3360D HDMI / DVI Level Shifter (IN STOCK!), a TFP410PAP TFP410 TI PanelBus™ Digital Transmitter (NO STOCK!),

According to the datasheet, “The LVDS25E/subLVDSE differential output buffers are available on all banks but the LVDS/subLVDS input buffers are only available on Bank 3 ofiCE40 LP/HXdevices.” ***Those are INPUTS but there are no special OUTPUT pins.***

I have replaced the LDO with was giving me trouble previously and am making this version USB programmable so it could be a useful for others as a cool video kit.

*****

Revisiting FPGA programming, here is where I got to last time :

Here is my process for the FPGA programming so far :

1. I signed up for an account at www.latticesemi.com.
2. I got a licence for iCEcube2, put it somewhere easy to find and took note of the directory, and downloaded iCEcube2 and the Lattice Diamond software from here : https://www.latticesemi.com/en/Products/DesignSoftwareAndIP
3. I plugged in the iCEstick and it blinked in a circular pattern. I also checked that it had a port under Device Manager (it had 2!). 
4. I went into iCEcube2 then to Help > Tutorial to open a pdf called “Implementing the Design” and followed the following steps :
   1. Start new project (iCE40, HX1K, ?TQ144?)
   2. Add Design file iCElab.v and Constraint file iCElab.sdc and checked the Device Info.
   3. Run Synplify Pro Synthesis
   4. Select Implementation
   5. Add constraint file iCElab.pcf under Import P&R Input Files.
   6. Run Placer
   7. Check the Floorplan, package view, timing analysis, power estimation
   8. Generate the bitmap (.bit and .hex files) which is saved wherever the project was saved. (For instance C:\Users\Jonah\Desktop\FPGA LATTICE DEMO PROJECTS\quick_start\quick_start\quick_start_Implmnt\sbt\outputs\bitmap).
   9. Here is what everything should look like once finished :
   10. 
5. I then transitioned to Youtube for a detailed explaination of using Diamond Programmer with the iCEstick here : https://www.youtube.com/watch?v=Df9k1T0bHmA&ab_channel=Dom
   1. Launch Diamond Programmer and take the default options (or click scan and take those). Important to note that you must launch Lattice Diamond Programmer directly, not through Lattice Diamond, in order to find the iCE40HX1K chip.
   2. It will mistake the board for a JTAG interface and give the following errors : “Failed to scan board”, “Scan Failed – Creating Blank Programmer Project.”
   3. Now change the Device Family to iCE40, the device to iCE40HX1K, and under Program enter the following information :
      1. Change Access mode to SPI Flash Programming and now some other options appear. Select > Vendor: Micron, Device: N25Q032, Package:  8-pin VDFPN8
      2. Now load the bitmap (.bin) file and check that it has a non-zero datasize :
      3. 
      4. Click OK and then click the green traffic light on the next to top row of icons. You should then see a completion message and have the program on your board :
      5. 
      6. Presto !

Just for info :

For the actual pinout of the ice40 (which you can change in Pin Constraints Editor):

***

And here is my attempt programming my own board with the Lattice Programmer.

I followed the same steps as above but instead selected the HW-USBN-2B (FTDI) programmer. Important to note that you must launch Lattice Diamond Programmer directly, not through Lattice Diamond, in order to find the iCE40HX1K chip. Also note that you need Lattice iCEcube2™ Software, not just Diamond for some reason.

Here are the color connections needed from the Lattice Programming Cables User Guide :

The USB power and Board power lights should be on on the programmer and the Prog blue LED should flash a few times before the Done blue LED will flash and Lattice Programmer will display Operation: successful.

I am taking the example LED rotation verilog .v code :

module LED_Rotation(

    input  clk,
    output LED1,
    output LED2,
    output LED3,
    output LED4,
    output LED5

    );

               reg[15:0] div_cntr1;
               reg[6:0] div_cntr2;
               reg[1:0] dec_cntr;
               reg half_sec_pulse;                         

               always@(posedge clk)
                              begin
                              div_cntr1 <= div_cntr1 + 1;
                              if (div_cntr1 == 0)
                                            if (div_cntr2 == 91)

                                                           begin
                                                           div_cntr2 <= 0;
                                                           half_sec_pulse <= 1; 
                                                           end
                                            else
                                                           div_cntr2 <= div_cntr2 + 1;
                              else
                                            half_sec_pulse <= 0;                            

                              if (half_sec_pulse == 1) 
                                            dec_cntr <= dec_cntr + 1;                                          
                              end                                                            
               assign LED1 = (dec_cntr == 0) ;
               assign LED2 = (dec_cntr == 1) ;
               assign LED3 = (dec_cntr == 2) ;
               assign LED4 = (dec_cntr == 3) ;
               assign LED5 = 1'b1;
                                                     
endmodule

module vga_sync_test(
    input wire clk_in,
    input wire reset,
    output reg r0,
    output reg r1,
    output reg r2,
    output reg b0,
    output reg b1,
    output reg b2,
    output reg g0,
    output reg g1,
    output reg g2,
    output wire h_sync,
    output wire v_sync,
    output wire led,
    output wire locked_led
  );

wire clk_sys;
wire display_en;
//reg [9:0] h_count;
wire [9:0] h_count;
//reg [9:0] v_count;
wire [9:0] v_count;
assign  led = clk_sys;

localparam  h_pixel_max = 640;
localparam  v_pixel_max = 480;
localparam  h_pixel_half = 320;
localparam  v_pixel_half = 240;

//Check if we can create RGB colors
always @(posedge clk_sys) begin
  if (display_en) begin
    if (h_count < h_pixel_half
        && v_count < v_pixel_half) begin
      //Assign here your test color
      r0 <= 1'b0;
      r1 <= 1'b0;
      r2 <= 1'b0;
      g0 <= 1'b0;
      g1 <= 1'b0;
      g2 <= 1'b0;
      b0 <= 1'b1;
      b1 <= 1'b1;
      b2 <= 1'b1;
    end else if (h_count > h_pixel_half
            && v_count < v_pixel_half) begin
      //Assign here your test color
      r0 <= 1'b0;
      r1 <= 1'b0;
      r2 <= 1'b0;
      g0 <= 1'b1;
      g1 <= 1'b1;
      g2 <= 1'b1;
      b0 <= 1'b0;
      b1 <= 1'b0;
      b2 <= 1'b0;
     end else if (h_count < h_pixel_half
            && v_count > v_pixel_half) begin
      //Assign here your test color
      r0 <= 1'b1;
      r1 <= 1'b1;
      r2 <= 1'b1;
      g0 <= 1'b0;
      g1 <= 1'b0;
      g2 <= 1'b0;
      b0 <= 1'b0;
      b1 <= 1'b0;
      b2 <= 1'b0;
    end else begin
      //Assign here your test color
      r0 <= 1'b1;
      r1 <= 1'b1;
      r2 <= 1'b1;
      g0 <= 1'b1;
      g1 <= 1'b1;
      g2 <= 1'b1;
      b0 <= 1'b1;
      b1 <= 1'b1;
      b2 <= 1'b1;
      end
  end else begin
    r0 <= 1'b0;
    r1 <= 1'b0;
    r2 <= 1'b0;
    g0 <= 1'b0;
    g1 <= 1'b0;
    g2 <= 1'b0;
    b0 <= 1'b0;
    b1 <= 1'b0;
    b2 <= 1'b0;
  end
end

vga_sync vga_s(
      .clk_in(clk_in),         //12MHz clock input
      .reset(reset),           // RST assigned to SW1
      .h_sync(h_sync),
      .v_sync(v_sync),
      .clk_sys(clk_sys),       //25.125 MHz clock generated by PLL
      .h_count(h_count),
      .v_count(v_count),
      .display_en(display_en), // '1' => pixel region
      .locked(locked_led)      // PLL signal, '1' => OK
      );

endmodule

set_io b0 76
set_io clk_in 21
set_io led 99
set_io r0 81
set_io b1 75
set_io g2 91
set_io r1 80
set_io v_sync 87
set_io b2 74
set_io g1 95
set_io locked_led 142
set_io r2 79
set_io reset 2
set_io g0 96
set_io h_sync 88

$display("0.5 seconds");

run -all

module dut ( input clk ); 

`timescale 1ps / 1ps
module top_module ( output reg clk );

      dut instance2 (.clk(clk));

           initial begin
           clk = 1'b0;
           forever #5 clk = ~clk;
     end
endmodule

module top_module(
input clk,
input load,
input [511:0] data,
output reg [511:0] q);

always @(posedge clk) begin
       if (load)
           q <= data; // Load the DFFs with a value.
       else begin
          // At each clock, the DFF storing each bit position becomes the XOR of its left neighbour
          // and its right neighbour. Since the operation is the same for every
          // bit position, it can be written as a single operation on vectors.
          // The shifts are accomplished using part select and concatenation operators.

         // left                     right
         // neighbour              neighbour
           q <= q[511:1] ^ {q[510:0], 1'b0} ;
        end
    end
endmodule

`include "rule90.v"
`timescale 1ps / 1ps


module rule90_tb();
reg clk;
reg load;
reg [511:0] data;
wire [511:0] q;

rule90 DUT (
.clk(clk),
.load(load),
.data(data),
.q(q)
);

initial begin
#10
clk = 1'b1;
#10;
clk = 1'b0;
#10;
load = 1'b1;
data = 1'b1;
clk = 1'b1;
#10;
clk = 1'b0;
#10;
load = 1'b0;

end

always #10 clk = ~clk;
endmodule

Making things easier, simpler, more plug and play.

****

Workshop
Organize parts 

Palimpsest.OS
Get all channels working 
Get raspberry pi VGA out working 
Test with raspberry pi VGA put 
Fix VGA input/output (I know what the problem is at least :)!
SPI SRAM 
Get recording as fast as possible 
Try with 4MB FRAM ?
New board with several + raspberry pi + snake-like channel overwriting?

FPGA
Try simple VGA with LatticIce40
Solder FPGA board 

I’ve got a Raspberry Pi Zero outputting VGA nicely. On startup it launches VLC in fullscreen and plays a playlist of iconic film excerpts. I activated hotplugging so it keeps looping even if the adapter is unplugged for long periods of time.

I used Win32DiskImager and downloaded the ISO Image Raspberry Pi OS with desktop (around 1GB) from the officiql website (https://www.raspberrypi.com/software/operating-systems/) and put it onto an 8GB SD Card.

In terms of connectors I needed a SD Micro > SD card adapter, HDMI mini > HDMI, an HDMI > VGA, a USB A > USB Micro for power, and a USB Micro to USB A female in order to plug in a mouse / keyboard.

I followed these three tutorials for setting up VLC autoplay and turning off annoying VLC text:

https://forums.raspberrypi.com/viewtopic.php?t=17051

Raspberry Pi: Run VLC on startup and play slideshow videos/pictures from folder

https://www.shellhacks.com/raspberry-pi-force-hdmi-hotplug/

Now adding a power off button (not good to pull the plug while running)

https://howchoo.com/g/mwnlytk3zmm/how-to-add-a-power-button-to-your-raspberry-pi

**EDIT The rasbpi turns off when I unplug HDMI or plug into the palimpsestOS. Is it because RGB are mixed with only 100ohm resistors ? Should I have 3 blocking caps and then mix after ?

Here’s a write up on how to VGA :

https://chipnetics.com/tutorials/understanding-75-ohm-video-signals/

Looks like parallel 75ohm resistors going to GND from the input is good practice + a cap and 75 ohm resistor on output?

VGA OUTPUT examples :

If I understand this last one, three parallel 75ohm resistors makes a 25ohm resistor. 97ohms gets 80% of 3.3V gone before the 25ohm dissipates the rest so that there is 0.7V left for the 3 channels. For a 5V supply like mine, I’ll need to remove 86% of 5V to get it down to 0.7V.  A 160 ohm resistor then ?

VGA INPUT examples :

*EDIT Made the changes (RGB colors in to GND through 75ohm, one color through cap to bias + 160ohm and now there is no output…But maybe it was already broken at this point? Can test when new converters arrive.)

Looked at some VGA in/out boards I had in my possession and saw the following :

• H and V sync can go to a 74HC125 Line Driver / Buffer.
• Color returns can be conected together and grounded along with chassis.
• Examples of color pins going to grounded 75ohm resistors then on to blocking caps. Also colors to gates of transistors.
• Colors also going to video signal switcher like this : QS4A210 – 2-Channel 4:1 Analog Mux/Demux
• Definitely DO NOT ground pin 9 (which is 5V), as I have done in all previous boards…

****

An older HDMI to VGA converter broke so I opened it up to see if I could reproduce it. It’s an ALGOLTEK AG6201 which appears to be not accessible anywhere but the manufacturer’s website.

The alternative is using a video chip which can trasmit HDMI like this project : https://hackaday.com/2019/07/26/hdmi-from-your-arduino/ which uses a CH7035B HDMI encoder.

Alternatively I use the HDMI to VGA adapter and solder a D Sub Standard Male connector (https://www.mouser.fr/ProductDetail/TE-Connectivity-AMP/2301843-1?qs=rrS6PyfT74crws9wAQVNoA%3D%3D&mgh=1&vip=1&gclid=Cj0KCQjw27mhBhC9ARIsAIFsETE7Rp9JFGXhYFAXh_Z2YbQUB2NfHqO8rM7yPueb-T3yFiKbUMvJkOEaAtjJEALw_wcB) to the board.

***

I will be testing a pico projector and a VGA capture device soon…

***

Trying again with SPI SRAM

This code seems solid to me but I can’t go beyond 100Hz…

#include <SPI.h>
#include <SRAM_23LC.h>

// SPI bus can be SPI, SPI1 (if present), etc.
#define SPI_PERIPHERAL    SPI
#define CHIP_SELECT_PIN   8

/* Device can be:
 * 128KB: SRAM_23LCV1024, SRAM_23LC1024, SRAM_23A1024
 * 64KB: SRAM_23LCV512, SRAM_23LC512, SRAM_23A512
 * 32KB: SRAM_23A256, SRAM_23K256
 * 8KB: SRAM_23A640, SRAM_23K640
 */
SRAM_23LC SRAM(&SPI_PERIPHERAL, CHIP_SELECT_PIN, SRAM_23LCV1024);

// Additional SRAM chips
// SRAM_23LC SRAM1(&SPI_PERIPHERAL1, CHIP_SELECT_PIN1, SRAM_23LC512);

#define START_ADDRESS   0

//uint8_t buffer[BUFFER_SIZE];
//#define BUFFER_SIZE  320

char buffer[1000];
#define BUFFER_SIZE  (sizeof(buffer) / sizeof(uint8_t))

void setup(void)
{
  pinMode(2, OUTPUT);
  /* Without parameters, begin() uses the default speed for this
   * library (12MHz for samd, 14MHz for sam, and 4MHz for avr).
   * Note that SPI transaction support is required.
   */
  SRAM.begin();
 // SRAM.begin(8000000UL);      // or specify speed
  //Serial.begin(9600);
}

void loop(void)
{
  //while (!Serial); // Wait for serial monitor to connect

// Record a series of values
  for (size_t i=0; i < BUFFER_SIZE; i++) {
    //buffer[i] = byte(digitalRead(A2));
        if ( (PINC & (1 << PINC2)) == (1 << PINC2) ) { //PC2 is what we're reading
        buffer[i] = 0xFF;// pin is high
        }
        else {
        buffer[i] = 0x00;// pin is low
        }
  }
/*
  // Print buffer to serial monitor
  Serial.print("Write Block: ");
  for (size_t i=0; i < BUFFER_SIZE; i++) {
    Serial.print(buffer[i], DEC);
  }
  Serial.println();
  */

  // Write block
  if (!SRAM.writeBlock(START_ADDRESS, BUFFER_SIZE, buffer)) {
    //Serial.println("Write Block Failure");
  }

  // Clear buffer
  //memset(&buffer[0], 0, BUFFER_SIZE);

  // Read block
  //Serial.print("Read Block:  ");
  if (!SRAM.readBlock(START_ADDRESS, BUFFER_SIZE, buffer)) {
    //Serial.println("Read Block Failure");
  }

  // Print buffer to serial monitor
  for (size_t i=0; i < BUFFER_SIZE; i++) {
    //Serial.print(buffer[i], DEC);
   if(buffer[i] == 0x00){
     //digitalWrite(2, LOW);
      PORTD &= ~(1 << PD2);    // set pin 2 of Port D low
   }  
   else{
    // digitalWrite(2, HIGH);
      PORTD |= (1 << PD2);     // set pin 2 of Port D high
   }
  }
  //Serial.println();
  //delay(1000);
}

I just can’t manage to get the same level of control with an SPI device as with parallel SRAM and counters.

****

New board time 😀 ! Test new things but keep the plug and play idea from last board and make even more so. SPEND MORE TIME SANITY CHECKING THE DESIGN and double checking pull ups and downs.

Goals :

• How about using a 16Mbit SRAM to store 128MBits of data with only a few added components ?! The plan is a pair of shift registers to convert serial output from a comparator into 8 bits to be sent all at once to the SRAM and the inverse on the output side. I would need the shift register clocks to be 8 times faster than the SRAM I think?
• Make it so power (5V – with an LDO on board to eliminate possibility for accidents) can be shared with a double power jack. Reverse polarity protection.
• A fine and coarse threshold selection !
• proper VGA input and output good practices that will never harm anything sending video signals in or recieving signals sent out (blocking caps, 75 ohm impedence matching, Vref for top side of variable comparator bias!!, buffers for H and V sync!!, two cables close together!! and shielding – guard rings? – on the PCB for these traces!! different grounds for different parts of the VGA cable, use BNC connectors for RGB??)
• Raspberry pi as input VGA through converter which plugs into a male VGA on the board, add an OFF/ON switch to safely turn off
  
• pass thru VGA signal switch !!
• Have different clock cans to switch between?
• Extended Display Identification Data chip as a test?
• Have audio out option ?

Here’s the preliminary circuit :

From https://www.cs.unca.edu/~bruce/Fall11/255/Labs/Lab13AnalogInput.html

From https://electronics.stackexchange.com/questions/144530/circuit-for-a-coarse-and-fine-setting-potentiometer

****

As for PCB inspiration, perhaps something that evokes the computer video graphics card :

Rectangular, with metal bracket (these are called Computer brackets in the Circuit Board Hardware – PCB category of Mouser.fr. They come in low profile or high profile), fan, heatsink, memory bank in a row, name of the board somewhere, PCI connector

****

Here is my first attempt at simulating the logic :

The only tricky part was activating parallel load of the output register only once per 8 clock cylces.

This design includes a giant FPGA to control enables all broken out along the PCI-E connector (that could be played like a piano with an alligator going to GND) in time and also to match the aesthetic of the video card. It would feature a stunning 128 Mbits (16MBits SRAM x 8) of memory. Would be cool to have LEDs next to each memory which light up when that block is recording.

***

Building on the idea of making physical artefacts, Vivien Roussel had the idea of moving towards displaying the chassis of the computer along with these boards. There are loads of cool test bench computer cases that could be an inspiration for this :

****

Or a DDR SDRAM module as inspiration :

Here’s what it’s looking like in Eagle so far :

I still like the idea of a kind of piano controlling :

• 3x SRAM CS sel bits
• 3x COUNTER EN + individual RST

And of course :

• Threshold control (fine and coarse this time !)
• Clock DIV
• REC/PB

Here’s the board as ordered :

CIRCUIT DIARY :

• The fine and coarse pots appear to work very well.
• The clock divider works as expected. Though it might be interesting to be able to play with different frequencies too as it seems to be important to get the combination of sampling versus pixel frequencies.
• I checked and the serial clock is indeed being divided by 8 and inverted (albeit super noisy!) :
• The Overflow and CS signals appear to be working well (though I had a hard time soldering the resistor networks!)
• The !WR signal is as expected
• Possibly should have put pull-downs for the SRAM I/0 pins ?
• I should have made a timing diagram not just the simulation..
• The option to manually advance the OVERFLOW signals is cool because you can solder one SRAM and test only it without having to wait for its turn to come around !
• I have reached a problem : the 596 is not shifting the serial into parallel. I can see it trying (little mini signals getting through), but it is as if the I/O pins are being pulled low, but by what ? The SRAM ? I’ve confirmed we’re in write mode so they should be high Z. The Serial to Parallel converter somehow? But the I/O pins are inputs for this IC…Hmmm. Is it something to do with the open drain outputs (or the Schmitt trigger inputs?) on the 596 ? **EDIT : Had a 595 with the same footprint and substituted it, seems to be working now.
• So, the output is very stripey. I have removed the 75ohm resistor to ground and shorted the 100ohm to the output RGB pins. I’ve tried shorting the blocking cap and it makes things a tiny bit easier to see but overall it is barely legible as an image. I think it has something to do with the output parallel to serial conversion. Here is a sample of a capture :

• For some reason it can also work much better :

• I don’t understand how it is possible to see the screen while it is recording as there is no “pass-thru” option…. There is also sometimes quite a difference from what is somehow passing through while in record mode and what plays during PB mode. *EDIT*There is a noise issue, when the VGA input is plugged in there is static that is entering somewhere. Trying to locate it currently. *EDIT* it is coming from the VGA IN. Tried connecting a bunch of GNDs (digital GND, chassis GND, color return RED) but still getting nowhere trying to eliminate the noise.
• I ordered the wrong type of bracket, this one is for a double row VGA…
• I had an issue with SRAM D but then replaced it and all is good.
• I forgot to have a pre-amp before the comparator, this is essential otherwise you don’t get any in screen peaks and basically don’t see anything unless you’re really lucky. I used the Palimpsest.OS preamp and bias setup and it works fine.
• The tiny trimpots need to be replaced with actual knobs !!
• I forgot to add loop LEDs ! It would have also been cool to know which SRAM is currently recording.
• EVERYTHING IS WORKING I CAN’T BELIEVE IT. The solution was to just test everything with a simple ramp using the function generator and look at the play back. Then I checked the pins on the SRAM and saw funky signals for several address pins that looked like they were several signals being added together. Clearly when I soldered in a bunch more SRAM and there were tiny connections between five different address pins and an I/O that I did not notice. This was causing chaos. I found the connections and fixed them, now it’s recording just as expected and it’s so glorious. NOTES : I am using the op amp from Palimpsest.OS AND crucially, am connecting both Analog and Digital Grounds between the two boards and the VGA IN with VGA OUT.

***

While waiting for this board to arrive :

• Try different function generated patterns of hitting count 0 enable while recording on the 16Mbit version
• Test the 8 layer board ! *DONE*
  • Remove pin 9 GND and fix other issues with VGA in and OUT with VGA beakout PCB
  • Test on raspberry pi / computer IN *DONE*
  • Test feedback ! *DONE*
• Try mini projector *DONE*
• Try VGA capture device *DONE*
• Put restart button on rasbpi

*******************

*EDIT* It works with rasbpi when I connect only a color, GND, H and V syncs !! So much more convenient than previously.

• It might be cool to be able vary the mixing of the different channels
• The output image is quite faintweak, I think I should rexamine the resistors I put at the termination and maybe switch to B+W.
• It’s a bit muddy with several channels, would be cool to be able to filter that
• I need a path to feedback with a pot !
• Switched the output resistors to a 150ohm going to R,G,B and it works nicely.
• Dip switch hard to use without tool.
• Hard to see which direction switches are pointing in darker light

More technical ERRATA :

• Pin 1 of the 40MHz clock should be pulled HIGH to be enabled, not LOW as it is on the board !
• The THRESHOLD pot isn’t connected to GND on one side…
• I should have tied the CCLR (pin 10, which resets when pulled LOW) of the 590 to VCC with a 10K instead of leaving it floating connected to VSYNC. This made it malfunction.
• BIG PROBLEM : I ordered multiplexers (unidirectional) instead of analog switches (bidirectional) ! The ‘157 multiplexers mess with SRAM B’s I/Os when it is in READ mode (when the SRAM is outputing values on the I/O pins). I ordered a replacement that is pin compatible, the 74LVC1G3157 (DATASHEET : https://www.ti.com/lit/ds/symlink/sn74lvc1g3157.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1679316452048&ref_url=https%253A%252F%252Fwww.mouser.de%252F). EDIT* The new components work perfectly – everything is good !
• The Sync Clock IC is 3.3V not 5V…
• Image jumps around of course. When I try to record with the Burst AND IC which outputs !CLK, no writing can occur. I’m guessing this gate messes with the timing somehow? As a workaround I’m trying to connect the 4 AND’ed V SYNC counts to either the address counter IC Reset or to another reset somewhere. 
• Lots of noise on V SYNC, I should maybe have made the input and output VGA jacks right next to one another…
• Pin 9 of the VGA D-SUB 15 is VCC for the Display ID EEPROM chip – but I have it connected to GND !! In general I need to respect the rules around the different grounds and return pins in the VGA protocol and not just connect them all together. Hoping to fix this in the next version.

***

Thinking about making a board with a small 5″ screen / or a mini projector incorperated in it

Fabien suggests using an LCD driver from a normal sized computer screen for a smaller screen (but he says it will will in 16:9 format). The other option he suggests is to use an FPGA to control a screen directly with LVDS.

Artist Andreas Gysin’s LCD 1 from http://lcd.ertdfgcvb.xyz/

***

Just realized that I could have an raspberry pi using VGA directly from I/0 pins : https://fr.pinout.xyz/pinout/dpi#

****

Currently thinking the next PCB should be raspberry pi sending video through I/O (not through HDMI) and FPGA controlling SRAM. This would allow messing with the sequence of the memory recording / playback. Could make a compact version of this project (a kind of black box, deployable version) without many external components but with sililar functionality. I could test making the FPGA USB programmable board too. Of course it would also be programmable.

To get here :

• make the automated palimpsest.OS board
• make the simple FPGA VGA board

****

I am revisiting the SPI SRAM code with renewed patience, I actually wrote it first on paper !

Here is my simple buffer filling code first off :

const int buffer_size = 2000;  // Only 2K bytes of SRAM on the 328P
byte buffer[buffer_size];
void setup() {
  DDRC = 0b00000000;  // set PC2 as input pin
  DDRD = 0b00000100;  // set PD2 as output pin
}

void loop() {

  //  fill the buffer
  for (int i = 0; i < buffer_size; i++) {  // iterate through buffer
    for (byte mask = 0b00000001; mask > 0; mask <<= 1) {  // iterate through a bitmask
      if ((PINC & 0b0000100) == 0b00000100) {  // if input pin high...
        buffer[i] = (buffer[i] | mask);  // set this bit
      }
      else {
        buffer[i] = (buffer[i] & ~(mask));  // clear this bit
      }
    }
  }
  // read buffer back
  for (int i = 0; i < buffer_size; i++) {  // iterate through buffer
    for (byte mask = 0b00000001; mask > 0; mask <<= 1) {  // iterate through mask
      if ((buffer[i] & mask) == mask) {  // if bit in buffer is high...
        PORTD |= 0b00000100;  // ...write output pin high
      }
      else {
        PORTD &= ~(0b00000100);  // else, write output pin low
      }
    }
  }
}

I tried the mini projector but it didn’t like the signals I was sending it. I think I have to avoid intelligent interfaces that can decide to send or not along my signals. Wondering about the camcorder CRT viewfinder and if I should head back in that direction.

Here is a popular 4″ screen :

Inspired by the history of mounting circuits on wood with screws and wire, evoking John Cage’s prepared pianos. 

This iteration of the project is born of a few realizations :

1. VGA is an analog signal, it’s not digital.
2. The coolest effects are the simplest ones : XOR, HP and LP filters, comparators, etc. which can be easily made with discrete components.
3. A simple low frequency oscillator could control these effects with an LED > LDR voltage controlled resistor set-up. 
4. Two out of sync oscillators easily make a pattern that doesn’t repeat often and is difficult to predict.

Pedagogically and aesthetically I like this idea : it goes back to the basics of electronics, the history of electronics, and will show the materiality of video signals. This in contrast to the overly complex use of digital components to do basic modifications…

The three basic circuits :

*TESTED* This works (powered at 5V, with pull down 10K on input and the rest 1K and two BD135s) at lower frequencies (<100KHz) around 5V.  I added a 5K variable resistor (or an LDR + resistor) to increase the resistance of R1 and it varies the threshold !

*TESTED* Works using BD136 PNP, 10K for the pull down and 1K for the base protection. General purpose diodes. I replaced the pull down with a 5K variable resistor and got some messed up results in the MHz. Doesn’t need power – just takes it from the input signal ! (But VGA signal would need to be amplified in order to work. 

*TESTED* With a 104 cap and 5K variable resistor I can vary the filtering of a 5V function generator signal. 

****

OK we’re back to the original plan ! Here is the Palimsest.OS Rev.2 :

WHY ?

• This board is for the inauguration of the IFT at the DVIC. It has to demonstrate technical proficiency on behalf of the staff, and must run independently as an tech-art installation, modifying video independently day in day out. 
• Rev.1 didn’t work for microchip automation, this one should work smoothly(?). If everything works I could write code that executes different video manipulations. I also added selection LEDs to show the microchip doing its thing.
• This tests the 8 channel 1-bit WRITE/REWRITE memory idea (but not the more elegant SRAM + buffer idea of Fabien), with certain effects tied to certain channels
• Incorporates a simple to control XOR, comparator and HP/LP/BP filter into one board
• Has a stable clock setup with metal can oscilloscope, a gen lock IC, and V SYNC burst setup
• Tests an (expensive) programmable filter IC
• It is a test for a simpler, inexpensive 8 ch recorder board that could be a cool kit
• Does away with the ADC and all its pesky issues and trades it for a simpler 1bit “ADC”. 
• I’m also using 5V SRAM to avoid the headache of different logic levels (though this means I only have 4MB of SRAM versus 16MB).
• For testing purposes it can be soldered as a logic-controlled board or as a physical switch controlled-board. 
• Instead of having lots of jumpers for wires, I went for rotary switches to make things more plug and play. However this also means that there are fewer experminental tests that are facilitated (like disabling a single counter while recording etc.) that were possible on rev.1
• Can layer different recorded portions easily in theory
• Battery switch and edge potentiometers instead of knobs
• Theoretically could do feedback and echo tests with this board as it can read and write from and into memory simoultaneously 
• This board should be easier to work with than the previous stacked PCI-E motherboard design which made knob turning and mounting hard. 
• Instead of using generic octal logic ICs I went for more specific purpose ones.
• The board will be made at https://aisler.net/ instead of JLCPCB so I’m hoping for a really nice finish

Here’s a possible minimal installation with it :

****

PALIMPSEST.OS v2 ERRATA :

• Pin 1 of the 40MHz clock should be pulled HIGH to be enabled, not LOW as it is on the board !
• The THRESHOLD pot isn’t connected to GND on one side…
• I should have tied the CCLR (pin 10, which resets when pulled LOW) of the 590 to VCC with a 10K instead of leaving it floating connected to VSYNC. This made it malfunction.
• BIG PROBLEM : I ordered multiplexers (unidirectional) instead of analog switches (bidirectional) ! The ‘157 multiplexers mess with SRAM B’s I/Os when it is in READ mode (when the SRAM is outputing values on the I/O pins). I ordered a replacement that is pin compatible, the 74LVC1G3157 (DATASHEET : https://www.ti.com/lit/ds/symlink/sn74lvc1g3157.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1679316452048&ref_url=https%253A%252F%252Fwww.mouser.de%252F). EDIT* The new components work perfectly – everything is good !
• The Sync Clock IC is 3.3V not 5V…
• Image jumps around of course. When I try to record with the Burst AND IC which outputs !CLK, no writing can occur. I’m guessing this gate messes with the timing somehow? As a workaround I’m trying to connect the 4 AND’ed V SYNC counts to either the address counter IC Reset or to another reset somewhere. 
• Lots of noise on V SYNC, I should maybe have made the input and output VGA jacks right next to one another…
• Pin 9 of the VGA D-SUB 15 is VCC for the Display ID EEPROM chip – but I have it connected to GND !! In general I need to respect the rules around the different grounds and return pins in the VGA protocol and not just connect them all together. Hoping to fix this in the next version.

More Meta errata :

• It’s a bit muddy with several channels, would be cool to be able to filter that
• I need a path to feedback with a pot !
• Switched the output resistors to a 150ohm going to R,G,B and it works nicely.
• Dip switch hard to use without tool.
• Hard to see which direction switches are pointing in darker light

Oy vey ! I realized that I could just use an I2C RAM IC and save about a billion components. Here are the more plug and play simple boards I made in the aftermath :

Good news: The 328 works. 

ERRATA : I fried the logic chips with 5V :(. Resoldered new ones and looks good.  I think I need to be feeding in a signal that has already been digitized (like by a comparator). Otherwise I need to mess around with knobs to get the signal right around the threshold of the logic gates with bias setup. 

Good news: The 328 works. And I can see the effect of selecting different filters. I’m not sure why but it works best when the signal is coming in on A and I’m taking the output on B (or vice versa). I’ve also got a cap going from the output of the filter board before amplifying it again.

ERRATA: I ordered the wrong length of bussed resistor network. 

Good news: The 328 works. 

errata ^ Wrong footprint (and value!) for the digital potentiometer here… Will have to wait for the correct part to test this.

Good news: The 328 works and at least it produces an image !

errata ^ H SYNC and V SYNC plugged in to wrong pins on Arduino (should be PD3 and PB1 respectively).

Good news: The 328 works.

ERRATA : the PD pin (which enables ADC IOs when low) is pulled HIGH ! I resoldered it and now it’s working great. 

I chose a non PWM pin on the atmega to be the voltage control pin of the VCO… I soldered it to the nextdoor pin which can do PWM and all is good. 

ERRATA: I tried two chips, they both come up as unidentified FRAM when I have them speak on the serial running the demo codes…I should probably pull Write Protect (WP) HIGH just in case. Still not working…I will try replacing with a 23LC1024 serial SPI SRAM as it has the same pinout. 

***EDIT: Just saw this on the Adafruit website : “For the 4Mbit version, you should change this to: fram.begin(3)”…Still doesn’t work though.

I replaced with the 23LC1024 and am using the SRAMsimple libary which appears to work well. For some reason the digitalRead I’m doing in the setup is always returning 0 even if connected to 5V.

#include <SRAMsimple.h>
#defineCSPIN8       // Default Chip Select Line for Uno (change as needed)
SRAMsimple sram;       //initialize an instance of this class
/*******  Set up code to define variables and start the SCI and SPI serial interfaces  *****/
voidsetup()
{
uint32_t address = 0;                       // create a 32 bit variable to hold the address (uint32_t=long)
Serial.begin(9600);                         // set communication speed for the serial monitor
SPI.begin();                                // start communicating with the memory chip
  // And now the fun begins:
/**********Write a Single Byte *******************/
bool data = digitalRead(A0);                        // initialize the data
for(int i = 0; i <=5; i++){                 // Let's write 5 individual bytes to memory
    address = i;                              // use the loop counter as the address
sram.WriteByte(address, byte(data));            // now write the data to that address
    data+=2;                                  // increment the data by 2
}
/********* Read a single Byte *********************/
Serial.println("Reading each data byte individually: ");
  byte value;                                 // create variable to hold the data value read
for(int i = 0; i <=5; i++){                 // start at memory location 0 and end at 5
    address = i;                              // use the loop counter as the memory address
    value = sram.ReadByte(address);           // reads a byte of data at that memory location
Serial.println(value);                    // Let's see what we got
}
}

Not sure why…

*EDIT: Got the thing working with Fabien’s help !  

#include <SPI.h>
#include <SRAM_23LC.h>
#define SPI_PERIPHERAL SPI
#define CHIP_SELECT_PIN 8

SRAM_23LC SRAM(&SPI_PERIPHERAL, CHIP_SELECT_PIN, SRAM_23LC1024);

#define START_ADDRESS 0

void setup(void)
{
pinMode(2, OUTPUT); // where we write the recorded data to.
pinMode(A2, INPUT);
SRAM.begin();
}

void loop(void)
{
for(unsigned long i=0; i<128000; i++)
{
byte val;
if ( (PINC & (1 << PINC2)) == (1 << PINC2) ) {
val = 255; // pin is high
}
else {
val = 0; // pin is low
}
SRAM.writeByte(START_ADDRESS + i, val);
}

delayMicroseconds(1);

for(unsigned long i=0; i<128000; i++)
{
byte ch = SRAM.readByte(START_ADDRESS + i);
PORTD = ch;
}

delayMicroseconds(1);
}

However in this byte write/read mode the fastest I can get it going is 10KHz…The next step is to use this SPI tutorial (https://docs.arduino.cc/tutorials/generic/introduction-to-the-serial-peripheral-interface) and the SRAM datasheet ( https://ww1.microchip.com/downloads/aemDocuments/documents/MPD/ProductDocuments/DataSheets/23A1024-23LC1024-1-Mbit-SPI-Serial-SRAM-with-SDI-and-SQI-Interface-DS20005142.pdf) to operate in “sequential operation” mode where pages are ignored and its all just one big array. 

I have tried to do this but haven’t yet succeeded. I can successfully write and read from the memory with the code below..:

#define DATAOUT 11//MOSI
#define DATAIN 12//MISO
#define SPICLOCK 13//sck
#define CHIPSELECT 8//ss

//opcodes
#define READ 0x03 // read data
#define WRITE 0x02 // write data
#define WRMR 0x01 // write to the Mode Register

//modes
#define SEQUENTIAL 0x20 // 0100000 in Binary

byte clr;

byte address0 = 0;
byte address1 = 0;
byte address2 = 0;

byte data_to_write = 0;
byte data_to_read = 0;

char spi_transfer(volatile byte data)
{
SPDR = data; // Start the transmission
while (!(SPSR & (1<<SPIF))) // Wait the end of the transmission
{
};
return SPDR; // return the received byte
}

void setup(void)
{

pinMode(DATAOUT, OUTPUT);
pinMode(DATAIN, INPUT);
pinMode(SPICLOCK,OUTPUT);
pinMode(CHIPSELECT,OUTPUT);
digitalWrite(CHIPSELECT,HIGH); //disable device
pinMode(2, OUTPUT); // where we write the recorded data to.
//pinMode(10, OUTPUT); // LED
pinMode(A2, INPUT); // where we read the data from
// SPCR = 01010000
//interrupt disabled,spi enabled,msb 1st,controller,clk low when idle,
//sample on leading edge of clk,system clock/4 rate (fastest)
SPCR = (1<<SPE)|(1<<MSTR);
clr=SPSR;
clr=SPDR;

digitalWrite(CHIPSELECT,LOW);
spi_transfer(WRMR); // access the Mode Register
spi_transfer(SEQUENTIAL);//enter Sequential Mode
digitalWrite(CHIPSELECT,HIGH); //disable device
}
void loop(void)
{
//WRITE
digitalWrite(CHIPSELECT,LOW);
spi_transfer(WRITE);
spi_transfer(address0);
spi_transfer(address1);
spi_transfer(address2);

for(unsigned long i=0; i<128000; i++) // address is automatically incremented internally in the SRAM in this mode
{
if ( (PINC & (1 << PINC2)) == (1 << PINC2) ) {
data_to_write = 255; // pin is high
} 
else {
data_to_write = 0; // pin is low
}
spi_transfer(data_to_write);
}
digitalWrite(CHIPSELECT,HIGH);

//READ
digitalWrite(CHIPSELECT,LOW);
spi_transfer(READ); //transmit read opcode
spi_transfer(address0);
spi_transfer(address1);
spi_transfer(address2); // 24 bit address in three parts (this could be a problem)

for(unsigned long i=0; i<128000; i++)
{
data_to_read = spi_transfer(0xFF); //get data byte
PORTD = data_to_read;
}
digitalWrite(CHIPSELECT,HIGH); //release chip, signal end transfer
}

…but when I do this in chunks with loops it doesn’t appear to work. I’m not sure if it’s because I’m reading the value of the pin during the writing and if I should perhaps do this before with a buffer array and then just read from it ?

OVERALL ERRATA : I also need some kind of power board that distributes 5V and 3.3V 

***

On the back of the boards I tried an experiment using the bmp import ULP in Eagle. Not sure what the results will look like :

   An

**** 

I also starting thinking that I should probably look at more existing DIY and pro analog video synth circuits…

A collection of great video synthesizer schematics resources : https://scanlines.xyz/t/diy-resources-file-system/224

Here are some of the ICs (that are still being manufactured) that I haven’t work with before that appear in several designs :

• Resettable and retriggerable Monostable Multivibrators : https://assets.nexperia.com/documents/data-sheet/74HC4538.pdf
• High speed diff comparators : https://www.ti.com/lit/ds/snosbj5c/snosbj5c.pdf?HQS=dis-mous-null-mousermode-dsf-pf-null-wwe&ts=1676232730602&ref_url=https%253A%252F%252Fwww.mouser.fr%252F
• Video Fader IC: https://www.analog.com/media/en/technical-documentation/data-sheets/12516fa.pdf
• Graphic EQ display filter : https://www.sparkfun.com/products/10468

To divide a signal into 8 different bands (if you skip the MUX at the end) :

Here’s a simple implementation with a 4051 analog mux at the end :

This worked after I sorted out that the Atmega 328 reset was pulled LOW all the time – so it programmed fine but never did anything after that. I also removed the op amps which were supposed to follow the selected thresholds, I connected the top and bottom directly to the pots in the end. I tried slowly switching between bands at half a second and also faster at 50ms. Both as expected.

And I’m revisiting all kinds of combined capacitor + switch circuits which move tiny charges around based on signals  :

• sample and hold 
• bucket brigade
• comb filter 
• switched capacitor circuit

 I have made this bucket brigade “delay” with 50 microchip tunable (variable) 100-200pF capacitors :

I am now curious about some other capacitor switching circuits like this Comb Filter : https://en.wikipedia.org/wiki/Comb_filter which somehow “provides response” at different multiples of 1KHz depending on 3 bit code. All the caps are the same value.

Here is another circuit design for the same function :

****

For the FPGA board, I’ve ordered an iCE40HX1K development board and am currently planning to test some basic VGA signal generation. The next steps could involve basing a design off of the OLIMEX dev board design (https://github.com/OLIMEX/iCE40HX1K-EVB/blob/master/ICE40-1KEVB_Rev_A.pdf) which already has SRAM and VGA OUT along with code on the internet (which I would follow closely for the first iteration). I would alter the board to be able to program directly via USB using the components from the Ice40 stick ( https://www.mouser.fr/new/lattice-semiconductor/lattice-icestick-kit/), like a fancy new FTDI chip, so I could stay within the Lattice software for my first steps. 

Compared to the VGAX, the FPGA could generate signals much faster (being clocked with a 100MHz crystal versus the 16MHz of the Atmega), it would also be producing signals based on a a different coding paradigm (I have no idea what that would mean in terms of images), and because it has around 90 I/O it could also work with super deep colors using only a R2R ladder. The possibility of using an SDRAM is so cool but it seems hard to implement, with SRAM being much simpler to interface. The OLIMEX has only 512KB of SRAM, so I couldn’t really record a lot with it. 

****

Here is my process for the FPGA programming so far :

1. I signed up for an account at www.latticesemi.com.
2. I got a licence for iCEcube2, put it somewhere easy to find and took note of the directory, and downloaded iCEcube2 and the Lattice Diamond software from here : https://www.latticesemi.com/en/Products/DesignSoftwareAndIP
3. I plugged in the iCEstick and it blinked in a circular pattern. I also checked that it had a port under Device Manager (it had 2!). 
4. I went into iCEcube2 then to Help > Tutorial to open a pdf called “Implementing the Design” and followed the following steps :
   1. Start new project (iCE40, HX1K, ?TQ144?)
   2. Add Design file iCElab.v and Constraint file iCElab.sdc and checked the Device Info.
   3. Run Synplify Pro Synthesis
   4. Select Implementation
   5. Add constraint file iCElab.pcf under Import P&R Input Files.
   6. Run Placer
   7. Check the Floorplan, package view, timing analysis, power estimation
   8. Generate the bitmap (.bit and .hex files) which is saved wherever the project was saved. (For instance C:\Users\Jonah\Desktop\FPGA LATTICE DEMO PROJECTS\quick_start\quick_start\quick_start_Implmnt\sbt\outputs\bitmap).
   9. Here is what everything should look like once finished :
   10. 
5. I then transitioned to Youtube for a detailed explaination of using Diamond Programmer with the iCEstick here : https://www.youtube.com/watch?v=Df9k1T0bHmA&ab_channel=Dom
   1. Launch Diamond Programmer and take the default options (or click scan and take those)
   2. It will mistake the board for a JTAG interface and give the following errors : “Failed to scan board”, “Scan Failed – Creating Blank Programmer Project.”
   3. Now change the Device Family to iCE40, the device to iCE40HX1K, and under Program enter the following information :
      1. Change Access mode to SPI Flash Programming and now some other options appear. Select > Vendor: Micron, Device: N25Q032, Package:  8-pin VDFPN8
      2. Now load the bitmap (.bin) file and check that it has a non-zero datasize :
      3. 
      4. Click OK and then click the green traffic light on the next to top row of icons. You should then see a completion message and have the program on your board :
      5. 
      6. Presto !

Just for info :

For the actual pinout of the ice40 (which you can change in Pin Constraints Editor):

Generating your own .v file, you can open Notepad++ and paste :

module AND( input A, input B, output Y ); assign Y = A&B; endmodule

***

Here’s what ended up getting presented :

Here is the text I made to go with it :

My takeaways :

Do something simple, and humble, but try to do it well. Trying to do too many things, or a “universal” thing, or a multi-functional reprogrammable thing is really ambitious. This has happened to me before :

• At the Barilla Hackathon (the team that did the best made a simple lunch surface, it was simple but really well made and designed). 
• With my solar robot project (the one that was supposed to run on solar energy and no battery, interact with other robots, and possibly build a structure)
• With my original solar sunflower design that was supposed to look super intricate.

Making a machine that works for a demo is the highest level of challenge. It requires you to master the functining of the machine to a high degree to be able to fix it and adapt in changing conditions. It you do something simple, you have a higher chance of being able to do this.

It would have been important to realize that the place this was to be shown is a corporate environment, and that my interest in the bodge / bricolage would never have found its place here. The corporate mentality is shiny, new, pro-tech, and “impressive”. I should have understood this before taking the project. 

The simple, distilled, purified, humble and clear idea from this project was the wooden-mounted electronic circuits. This would have been in line with my “design research” interests, my aesthetic.

If I were to make a complex machine like the one I had in mind for this expo that would have worked, I think I would have to change the following things :

• Generate my own VGA signals. For plug and play things, generating this in software seems so much easier because you are the one making it and you have control over what is being produced. 
• Figure out, once and for all, the story around shared grounds and blocking caps, and bias pots, and voltage in and voltage out levels, for different modules. Also, 75ohm resistors and small caps before VGA out ? Should I just get a VGA driver chip that works? (EDIT: Here is an explaination of how to calculate the output impedence for VGA cables : https://hackaday.io/project/18682-pic-graphics-demo/log/49786-vga-interface)
• I would need to figure out what makes the VGA monitor turn off (is it sending something it doesn’t consider a video, or a voltage level that is too high?)

I think the alternative, which would be showing pre-recorded videos, is uninteresting for a performance. Another key ingredient I think is having designers / artists to help me review the project regularly (like in design school). It should also be really clear to me if it is my design project or a commission (in which case I’m an engineer I guess?). I should also get clear right from the begining next time what are the conditions of the final thing – where will it be, what are the goals of the person commissioning the work, etc.). I should probably only work with people who share my interests and aesthetic ! 

I think I have to acknowledge that I have an extremely constrained working process that is highly method driven. I am not focused so much on the end product directly. My friend suggested I was over constraining myself. Basically there is a confusion between whether I’m using technology to stumble upon unexpected things, or whether I’m using it to make something that works. To work efficiently on things would work well would require time developing the things that must work well, and an organized, systematic working practice. I MUST ORGANIZE MY ELECTRONIC PARTS to make this process more efficient.

Also : all the intense pressure and hardcore work streaks I put in DID NOT HELP THE FINAL PROJECT – I can’t even think straight or debug basic circuits right now :(. It would have been better to perhaps start working on the final thing starting on day 1, with the EASIEST, SIMPLEST, AND MOST LIKELY TO WORK PAINLESSLY solutions. 

Another key question is what is the output, and who is my audience ? I need a way of mesuring my output and comparing it. 

• Am I making art for people who consume art ? (then I have to move towards very simple projects and focus on their EXECUTION while photographing everything super well for my PORTFOLIO)
• Am I making “design research” papers/talks for academics and people who consume this ? (then I need to WRITE about my research)
• Am I making open-sourced electronics kits for hobbyists ? (Then I need to spend time ENGINEERING working kits that people would be interested in making)
• Am I making workshops for designers ? (Then I need to come up with simple exercises for workshops?)

And am I doing several of these things simoultaneously ? I think doing any one of them well first could take a lifetime already ! My friend suggested projecting five years in the future to where I would like to be and building backwards from there. I think I would most like to be a teacher who does art/design research in the form of expos, articles and classes (a bit like Andrew Witt at the GSD).

********

Where I would like to go from here :

1. Test my basic FPGA VGA board. What can it do with video ? Possibly make another pro version (USB programmale, nicely laid out, SRAM). FPGAs feel like the future because they are good a processing video in parallel, and because coding them is essentially like building 74 series logic circuits but without all the soldering. It could also lead to some cool machine learning experiments later on..
2. Test my automatable SRAM 4MB board. What kind of automatic looping can it make?
3. Try to get the SPI SRAM board functioning (it is so simple it would be perfect for a video sampling workshop). It would be cool to see what kinds of images it produces. It works at 20MHz, it would be perfect !
4. Get Spaghettini working with aluminum board (just avoid going through-hole) – this is the simplest way to generate cool simple memory based video !
5. Have another stab at presenting my work as an art installation at my show end of march at La Générale. 
6. Try the bucket brigade and digitally controlled pot boards

*******

After my colleague Fabien told me about EDID EEPROMs, I am thinking it could be possible to mess with the memory of this EEPROM that communicates with the computer sending VGA signals and create some interesting glitches this way : https://en.wikipedia.org/wiki/Extended_Display_Identification_Data

Also check out these types of RAM : 

• https://en.wikipedia.org/wiki/Dual-ported_RAM
• https://en.wikipedia.org/wiki/GDDR_SDRAM

And this keeps coming up when looking into controlling screen rows and columns directly : https://en.wikipedia.org/wiki/Low-voltage_differential_signaling

Check out no input mixing and electro-acoustic musique concrete, and machine exorcism. 

Check out universal LCD driver IC RTD2556 on boards like this :

***

It looks like I could build my own HMDI to VGA converter with two AD ICs : https://www.analog.com/en/analog-dialogue/articles/hdmi-made-easy.html

I could combine this with a new board that uses a bunch of SPI SRAM memory chips controlled by arduino to approximate the 7 channel 4MB recording and mixing board I made. 

I could also put a rasbpi zero with just power, an SD card containing videos and an HDMI mini out. For the Raspberry Pi I made the HDMI hot pluggable (hdmi_force_hotplug=1) and put a bunch of low res mp4 videos in the boot SD card which are accessible.

 This circuit is a next version from the video synth. 

Some ideas from how this installation could look like :

Messing around with my last synths, here are some circuits that I want to be able to reproduce with my new synth :

Here are some ideas of how the circuit could take form :

A Nintendo gameboy catridge teardown :

Some sketches of possible configurations :

*******

I am currently splitting the project into two parts : 

PART 1 : A series of independent transforming modules, VGA IN/OUT with screens, and oscillators with patch cables.

PART 2: A board called palímpsêst.OS which is a rack (or archive) of several 16MB memory modules. 

***********

Palimpsest.OS

Each memory will share the same power (5V, 3.3V, GND), timing CLK signals, control signals (to enable/disable counters, buffers, RAM, ADC etc. and to RESET things). All this can be automatically controlled by an microchip which can turn on/off these memory banks individually in time. Despite this there will be basically all the components on the board to make it function independently and, most importantly, test and debug it’s functioning. 

Just like for the previous memory board, the following parameters will be modifiable :

• the duration of the recording and playback,
• the sequencing of addressing this memory,
• the amplification of the incoming and outgoing video data,
• the sampling rate and sampling pattern of video recording and playback,
• the bit resolution of the recording and playback,
• the continuity of the above processes or the frequency of their interruption

I have corrected the errata from the previous 16MB memory board, removed jumpers (as this board will be made by JLC PCB), added a ground plane, made it more compact (by removing the burst record functionality, level shifting, and having two layers). I also added a battery so that memory is persistent as long as the battery has juice. The main work however has been breaking out pins to a bus which can be controlled by a microcontroller. There is now the possibility to have 3 memory boards A,B and C, and to control their recording and playback, and all the parameters of these two things that can easily be controlled, in time. 

With these boards it should be possible to take an input, record it, then play it back and mix it with the input through a feedback pot. Because this can be done by three memories, they can also record their respective outputs and layer without any mixing with the VGA . 

*****

01/12/2022 UPDATE :

So far debugging: For some reason the ADC is not spitting out anything, regardless of what I feed it. I changed the input op amp and it had no effect. Previously to soldering the ADC everything seemed to be working…As far as I can tell the memory is working and all the bias pots too.

ERRATA :

-The direction pin of the 245 buffer connecting to the R2 ladder is wrong – it should be HIGH instead of LOW.  To temporarily correct this involves jumping the DIR pin to VCC – AND CRUCIALLY – to ALSO disconnect this pin from GND unless you will have a short.****

-Why on earth did I connect all the pins without dip switches (ADC EN, 1/0 0-7, etc.) from the memory boards together ? This makes it impossible to record on one board and not on the others. I cut the non-DIP’d traces and it seems to work. 

-the LED needs a current limiting resistor or it just explodes.

-one switch for master record (WR EN and ADC EN)?

-I should follow the ADC1175 instructions and isolate the DGND and AGND with caps. 

-Should have an input pin and 5V pin for testing on board.

-I should add the right footprint for a big capacitor at the input of the ADC (I forgot and put a 0.1uF which didn’t work).

-It would be super cool to have a coarse and fine knob (and or a super precise pot) for the VCO for instance on the base board. 

-I should take the classic gameboy battery footprint.

-There isn’t an extra pin so I can send V SYNC both to be frequency divided and pass it on to the VGA out. 

-The populated side of the memory PCB is facing “backwards” with regards to the base board…

-The LDO pinout on the base board is wrong

-I can’t plug in standard jumper headers to the PCIe breakout pins because they are a different diameter

-I tried hard syncing the VGA’s H Sync with the 4046 ( see text in description of video here : https://www.youtube.com/watch?v=S694YY7sJMw&ab_channel=drumasaurusrex ). It only works with the V Sync but that’s too slow. I can’t get a stable signal out, it looks super wobly at high frequencies.  

*****

TESTING THE PALIMSEST.OS

• Not sure why but it seems like I can’t record only on one board when multiple boards are connected. I have to disconnect all but the board I want to record on to get a recording onto it. *EDIT* Because I connected all the non-dipped pins from the boards together via the PCI-E bus…
• It would be super cool to be able to send different clock signals to each board. I should maybe not have made the same CLK hardwired to each board. 
• It’s not possible to turn the knobs when then three boards are plugged in at once because the pot shafts are too long. 
• Not sure exactly how the battery is working, it seems like it can “remember” something for a few minutes at least. 
• It’s hard to palimpsest various things together – You have to get one board all calibrated, then send it something from another calibrated board, record it, then rewrite to play it back. (I am hoping the new 8 channel 1 bit device makes things easier). 
• I can’t automatically have things read or write currently, not sure why it’s not working…
• I can’t echo with this board because I can’t simoultaneously read and write. That said I can mix a recording with live channel and then record that together into a memory and begin layering. 
• I would like to have the image stay stable instead of always jumping everywhere. 
• Dephasing the ADC and RAM clocks makesa large variety of nice patterns on the output !
• It would be nice to be able to count up and down and do that to 4 bits in the middle of memory !
• remember to connect GNDs if using memory board with analog f(x) for example
• Trying to hard sync with h sync and cd4046 based on these links (https://www.renesas.com/us/en/document/oth/tb476regenerating-hsync-corrupted-sog-or-csync-during-vsync and https://www.youtube.com/watch?v=5VymS65eefo&ab_channel=drumasaurusrex)… I think the solution might be an oscillator in a can (with 4 not 2 leads), which I can then divide. (I can still have a free style VCO with knob to control the sampling of the ADC though !)
• Works great with a four lead crystal oscillator can and the f divider – a very clean image that doesn’t warp ! You can still use the knob controlled high speed VCO to trigger the ADC and it’s a nice combo. 
• *****WOW – feeding in a quartz can 10MHz into a frequency divider (and sending diff divisions to the SRAM clock), and hooking up V Sync directly to the reset, produces a really stable image that doesn’t slide left or right !!!****
• ***ABOVE ALSO WORKS WITH H SYNC AT LOWER FREQUENCIES – SOOO COOOL : D !!
• I’m not able to use MOSFETs or transistors to reliably automate the switch from REC to PB for some reason. I’ve even tried using an optocoupler to isolate the arduino and also tried using and AND gate as a buffer with the WR signal but neither work. I think should use mechanical relays to get around this problem or just avoid it all together by having Arduino send the CLK and WR signals in the next version. 
• Tying differnt oscillator cans (10MHz, 12MHz, and 40MHz) 12 is nice because it doesn’t jump too much on my screen resolution (800×600). At 1280×720, 10MHz is nicest. 
• I did a proof of concept for the 8 track recording and rerecodording idea, it seems to work though there may be a bit of interference from neighbouring channels on one another ? Not sure how I would try to isolate them from one another but some bleeding might actually be cool ?
• I tried doing a feedback recording (recording a mix of a play back and a live feed) and had no success. Not sure why this isn’t working.

***********

Realizing that this whole massive multi-module thing could be made with just one memory module having feedback !!! That or a simple echo IC like this one I ordered (BU9253 : https://www.mouser.fr/datasheet/2/348/rohm_semiconductor_rohms16891-1-1742621.pdf ) :

That said the delay is only 8Kbits and it’s designed for audio.

*****

Analog Functions Board :

Trying to remake the previous analog functions board but at JLC and as pro-style as I can. The general idea is to make a bunch of op-amp circuits that modify video in various ways and that can be combined with the logic modification board to make a completely full suite of electronics video transformations. Not sure yet how they could be automated.

Fixes from previous esceptionally newbie laser engraved version :

• +15/-15V supply for all the op-amps using the handy ICL7660 negative voltage generating IC will hopefully solve many issues.
• Using normal general purpose op amps in addition to super fast video ones 
• Having bias pots at the inputs and outputs to sort out any different in offsets. 
• Doing more research to get better circuit designs, notably looking at the Analog Thing, The Hackaday Logic Noise Series, Rod Elliott’s active op-amp series.
• Making things less noisy with : seperated AGND and DGND, caps near op amps, following suggested board layouts, 2 sided board with GND plane (!)
• Tying to take into account impedence matching with 75ohm VGA camble at the input and output and testing a specialized video line driver IC
• Making op amp board with the possibility of automating thier switching / pot levels ?
• Adding over-amped fuz circuit, phase-shifter, and various filters (LP, HP, BP, Notch), and adding a reset to the integrator circuit. 

I think the theme of this board, especially seeing as I have 25 of these TL074 op amps, is showing the diversity of flavours (and range of sometimes exotic circuits) of the history of op amp filters, arithmatic, etc. circuits. I plan on highlighting the names (and dates?) somehow.

The idea has clarified now, it will be a grid of 24 different op amp circuits in a 6 by 4 grid with the name of each circuit and a letter/number identifier. At the top will be all the power, VGA in out and bias amps.

I collected the circuits from various places (AoE among them) but especially from Rod Elliott’s write up on active filters (which you can access with Internet Archive) : http://sound.westhost.com/articles/active-filters.htm

I am most excited about the combination of digital and analog – like in the switched cap filter, sample and hold, resettable integrator, and demux amp circuits. Being able to modify the functioning of am amp with digital signals (even with a tunable capacity and voltage controlled potentiometer) seems to offer really cool potential. This being combined with SRAM could be a really cool composite project.

ERRATA :

• VCCIO and GND directly overlapping on top layer  (near A2/A3) :/
• the preamp in and out and misaligned 
• Should have included blocking capacitors
• VGA not being recognized by my computer with driver chip 
• Should have included an inductor circuit
• awful humming from the negative 12V generator
• not enough room for 220uF caps for the video driver on board
• some kind of “pass through” switch would be useful to show what the input looks like
• the driver IC can only accept one color for some reason…I should not include it next time
• the female – female jumpers are not reliable and lead to weak contacts…maybe going towards jumpers?
• The thing is long to set up – it’s not plug and play and is finicky for demos
• Learn about the safety of hot plugging
• The Voltage Control works a litte, with a 1k8 resistor and picking the right voltage range. But it is not reliable, I should move to pot ICs for the next version. 

• A0  with a 200uF cap after the final amp has some filtering output
• A1  just tears the left side of the screen
• A2  nothing happening
• A3 varies nicely with different frequencies, though sometimes just looks like it’s “adding” frequency pattern to input
• A4 I think the original comparator design (with 1K resistor going to VCC and pot with middle shorted to GND going to GND is correct and this one wrong)
• A5 same note as above, but preamp in and upper seem to work. Perhaps the best way to get abstract forms from input super easily. 

• B0 Not working…
• B1 nice filtering !
• B2 needs blocking cap on output or else produces nothing. Goes from filtering to almost comparator like behaviour.
• B3 needs a cap on output and >20MHz to produce anything, no relation to input though ?
• B4 creates a cool zebra repeating effect at one extreme
• B5 great filter !! Both knobs do things and there is great range.

• C0 nothing cool happening here…Seems just to pass on a modified version of the digital in signal ?
• C1 top knob needs resoldering. Only does stuff when top knob fully to one side then behaves a bit like A3 but can go down to low frequencies on digital in.
• C2 Cool zebra like filtering (like B4 but messier and less repetitive.
• C3 nothing happening…
• C4 faintest image at one extreme
• C5 nice filter (like B5) ! Only top knob seems to do cool stuff though. (Other knob goes haywire at one extreme).

• D0 barely the faintest image at low frequencies…
• D1 the HP inverts the input !
• D2 Does add when the knobs are set right. I put a cap on the function generator input.
• D3 Does kind of subtract ! Can invert or not.
• D4 makes a banding across the screen, not sure what effect the 3 binary inputs have…
• D5 doesn’t really work but with the second multiplier input floating you can touch it and send the thing into an overdrive momentarily. 

*********

Notes from Museum visits :

void setup() {
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);
}

void loop() {
//WRITE
PORTB = B11101111; // CLK goes LOW/HIGH
PORTB = B11011111; //WR goes HIGH/LOW
}

unsigned long startMillis; //some global variables available anywhere in the program
unsigned long currentMillis;
const unsigned long period = 1000; //the value is a number of milliseconds
int WRState = HIGH; // the current state of the WR pin

void setup()
{
pinMode(13, OUTPUT); //WR PIN
pinMode(12, OUTPUT); //CLK PIN
pinMode(11, OUTPUT); //ADC EN PIN
startMillis = millis(); //initial start time
}

void loop()
{

if(WRState == HIGH)
{
currentMillis = millis(); //get the current "time" (actually the number of milliseconds since the program started)

//WRITE TO SRAM
PORTB = B11101111; // CLK goes LOW/HIGH, ADC_EN HIGH
PORTB = B11011111; //WR goes HIGH/LOW, ADC_EN HIGH
     if (currentMillis - startMillis >= period) //test whether the period has elapsed
     {
      WRState = !WRState;
      startMillis = currentMillis; //IMPORTANT to save the start time of the current LED state.
     }
}

if(WRState == LOW)
{
currentMillis = millis(); //get the current "time" (actually the number of milliseconds since the program started)

// READ SRAM
PORTB = B11100111; // CLK goes LOW/HIGH, ADC_EN LOW
PORTB = B11110111; //WR stays high, ADC_EN LOW

     if (currentMillis - startMillis >= period) //test whether the period has elapsed
      {
       WRState = !WRState;
       startMillis = currentMillis; //IMPORTANT to save the start time of the current LED state.
      }
}
}

I want to continue messing around with magnetic media (audio cassette players/recorders, floppy disk drives, video camcorders) and try to get them recording and playing back video.

Here is some inspiration :

From the timeless Hardware Hacking manual. The suggestion is to use a high gain amplifier to hear the results of the tape pickup. :

A very cool project putting video onto a cassette :

https://www.ubergizmo.com/2020/04/audio-cassette-tape-used-to-capture-video/

From this reply : https://electronics.stackexchange.com/questions/108907/create-input-jack-from-tape-head

“You can use the continuity tester to check for the ground lead. This should be connected to the metal shield of the head, you can leave it unconnected. You’ll want to connect the other two wires to your two inputs”

From this site http://stevecoates.net/walkman/ :

This https://makezine.com/projects/turn-old-walkman-scratchbox/ Make Magazine article connects simply :

Some very cool experiments with a disconnected tape head :

And a custom loop tape :

**************************

I began testing a bit, it looks like I can both see and hear the audio signals from the tape (yellow is R?, blue is L?):

It’s most audible right near the end (the hum is the tape cassette motor spining) :

*****************************************

The method is just to power the cassette rotating motor with around 3.3V, then hook up the red(R?) or white(left?) to a probe or audio in for an amp, and then the black (GND) – which looks like it’s connected to two pins – to GND.

The next step would be to try to amplify with a high gain op-amp circuit ? And then to begin trying to write ?

UPDATE :

Might be easier to work with the electronics already present on the board, learn how it works, desolder it and then put it on a breakout board to mess around with? Here is one of the simplest ICs I found on one of the dissassembled tape decks in an easy to solder SOP16 package:

I could order a series of boards like this to make tests with them :

UPDATE:

I plugged in the little audio amp into the Audio out jack of the device while I touched different pins on the IC. I found that the large slide switch on the back switched from REC to PLAY. I found that during REC mode the pins that caused the most amplification were the MIC IN and EQ IN. In PLAY mode I found the most important pin for producing output on the AUDIO OUT was LINE IN.

I also tried connecting the little speaker amp to the REC OUT, LINE OUT while I touched various pins. 

I was unable to amplify the tape head signals however with any of the various combinations I tried. I will try the other tape cassette circuit boards to see if I have any more luck, and also test the 2.5W power amp from Adafruit. Ideally I would be able to take an input, amplify it, send it to the tape head, then read it back by reversing the sequence after rewinding to the same section. This should also work with a strip of tape taped to a desk that I can manually run the magnet head over (right??). 

Once I’m able to do this, I want to try the same thing (amplify an analog signal, write it to the disk through the heads directly, then read the analog signal back off it) with the Floppy Circuitry. 

*************

A great VCR technical reference : https://www.wikiwand.com/en/VHS

I got my hands on a VCR, took it apart and broke out the cable coming from the helical read/write head.

It looks like there is one little board with all the drivers for the various motors. Might be able to control it. (See this video : https://www.youtube.com/watch?v=4F7xJOb32GI&ab_channel=LifeOfDiy). I’ve got a BA6878EFV 3-phase motor driver for VTR capstan, datasheets available online. It looks like you need to plug in GND (3), 5V (2), and then connect EC(7) and HYS OUT (9) together.

So far I haven’t been able to pick anything up on the oscilloscope from moving the tape across the print heads while listening in to various output pins.

https://www.wikiwand.com/en/VHS#Media/File:Medion_MD8910_-_VHS_Helical_scan_tape_head-8601.jpg

There appear to be two video heads (with two wires each – one wire for each electromagnet) and two audio heads (with one wire each) making a total of 6 wires with 1 dummy. It looks like the pinout is the following :

1. Video Green 1
2. Video Red 1
3. Video Green 2
4. Video Red 2
5. No connection (shortened turn)
6. Audio Red
7. Audio Green

It seems like others have two shortened turns to help isolate signals from one another.

I measured the resistances between the output pins:

1. grey 
2. white
3. blue(1)
4. green
5. yellow(1)
6. orange
7. red
8. blue(2)
9. yellow(2)

The following are connected :

Looking up the chip LA71750 ( Video and Audio Signal-Processing IC) – on the right in the image below – and the LA7264B (Audio Signal-Processing IC) – on the left – and checking out the datasheets and inspecting the PCB, looks like the following are the important connections :

From the LA71750 datasheet :

Would appear possible to make this pinout diagram :

I have tried connecting pins to the oscilloscope while moving the tape head, but even at 10mV level at various time scales I can’t see anything. 

UPDATE : Just seeing now that this chip takes control data in the form of I2C. It would be super hard for me to desolder the chip and make my own controller with it as a result.

******************

I have tried amplifying and sending 20V signals at various frequencies. 

Turning to more research for answers, check out these links :

Article about audio sampler made from floppy :

https://nime.pubpub.org/pub/uh76shf0/release/1

Video made from floppy :

Freespin is a demo made for the Commodore 1541 – no, not the computer, just the floppy drive

For more tech info about floppy heads :

http://forums.openmusiclabs.com/viewtopic.php?f=11&t=92&sid=9a4c3a6763f9bc02426c9d3910187e70

******************

From this reading break I think the following things should be attempted :

-with a >2W class D amp can I push some signal onto the tape that I can then read ? (Just afraid that it won’t be fast enough for video signals as it is made for audio signals ? Perhaps a high power high speed amp is even better?).

-I could get the same preamp LA IC used in the concentric sampler paper.

-Everyone seems to say, “try different combinations with the R/W heads” and “check continuitiy” and apply the signal to continuous wires. 

-I could try adding the bias oscillator to the signal I’m trying to R/W?

-I should get a super strong magnet for testing purposes

***********

Looking at my floppy drive, I found the following CX20185 chip which is a Read/Write Amplifier for Floppy Disk Drive.

It looks like the pinout is the following :

It looks like I could read the Preamp Out pins to read from the floppy. I’m not sure how I could yet wright to the floppy without giving data to the logic on the driver.

Here is me figuring out the pinout :

I turned on the floppy LED I have by connecting the sixth pin next to the stepper head motor to the GND, and turned on the central motor by connecting the 8th pin to GND and plugging in 12V as well :

When I listen in to READ DUMP A or B I can see voltage when I spin the disk manually (when I plug in the brushless motor it no longer responds to spinning):

When I listen in to PRE OUT A or B I can see the normally high voltage go down and vary :

Meh. 

Some stuff about data degredation :

https://fr.wikipedia.org/wiki/The_Disintegration_Loops

Project Kryoflux – Part 3: Recovery in Practice

******

Suggestion from research engineer at DVIC for the previous experiments:

-For the floppy, look at the input from head (but oscilloscope will probably mess this up), preamp, and digital out (READ OUT – which should be connected directly to the chip I have the datasheet for) at same time. 

-Basically you’re not going to see anything on the oscilloscope when looking at these electromagnets. It’s all in the very sensitive amp – so all the more reason to use the amp that comes with the device !

-Is the preamp chip IC I am looking at even enabled ? Check POWER ON.

-Try the floppy pinout here : https://old.pinouts.ru/HD/InternalDisk_pinout.shtml

-For the VCR, get the thing plugged in and functioning as it was in the beginning. Observe it first, then try to intervene (you’ll never be able to reinvent the thing from nothing !)

****

Listening to the DATA READ pin 33 while the disk is spinning :

****

UPDATES:

I learned from watching this (https://www.youtube.com/watch?v=DdMOGvKjrfk&ab_channel=JeffHxC2001) that the way to read is to sync the oscilloscope with the INDEX pulse. The Difference Out pin is the one being listened to in this video.

I learned from looking more into the floppy interface that the Head Select (32) is HIGH for BOTTOM and LOW for TOP head. I also learned that Floppy Write Enable (24) is HIGH to READ and LOW to WRITE. Finally, the READY pin 34 may need to be tied to GND.

From a Floppy Maintenance Manual showing the sequence : R/W head > Pre-Amp > Differentiator > Voltage Comparator > Time/Domain Filter > DATA OUT

UPDATES:

I think to make this project work, I would first need to *VERY CAREFULLY* observe the correct functioning of a working device without any changes made to it. I would need to be able to confirm completely the working of the machine, and see what signals are supposed to look like at each step. 

Only after doing this could I start intervening in this process.

I think Floppy is the best way to go – it’s part of the history of the computer (like all my other projects) which isn’t the case with the video recorder. The floppy is the best documented, easiest to source, and least expensive to work with. It already has a nice interface which is easy to use. It also is more standardized, unlike the many different kind of video recorders that exist. 

What is the most standard Floppy Drive Read/Write Amplifier ? The Sony CXA series (1360, 1720, 3010, 3071, 20185, etc.) seem to have specs available online. ROHM also have BH6xxx and BA6xxx series. 

Then again if I’m only going to be recording analog, I don’t need anything but the preamp (especially for reading) ? I could just take the tape preamps I have and put them on a breakout board ? I have BA3110, CX20023, and a CXA1262 to work with. I could try getting them to work amplifying the mic first, and also get the playback working. Then I could test putting analog signals on a floppy.

This workshop with La Diagonale at UP Saclay is a simple circuit to begin playing with code and screen patterns. 

Here is the github: https://github.com/merlinmarrs/spaghettini-video-synth

Arduino Coding and Video Synthesis Workshop

Lean to code in C with Arduino, solder and assemble a custom printed-circuit board made in the Fablab, and make your own algorithmically-generated video art!

This workshop is inspired by the improvisational music of Live coding (https://fr.wikipedia.org/wiki/Live_coding) and the burgeoning minimalist Bytebeats movement (https://nightmachines.tv/bytebeats-tutorial).

Our video synthesis kit plugs in to the Arduino (https://www.arduino.cc/), a reprogrammable embedded micro-controller that can interact with the world through code, and uses the VGAX library (https://github.com/smaffer/vgax) to generate funky video.

Meet other creative technologists and sharpen your expertise in computer sciences and electronics soldering!

Here are some initial sketches :

The functionality that is important is :

-being able to select between different programs (with button and leds to indicate)

-to be able to take audio in and have it modify the patterns on screen

-to be able to change the colors on the go

-I have since phased out the brightness changeability but I could add an LDR easily ?

*******************************************************************************************

Because our lasercutter is not operational, I am trying to make this circuit with the vinyl cutter using 5cm wide copper tape. 

I am worried about the headers getting pulled out when plugging/unplugging. I will try adding some hot glue to fortify them. The other option is potting the circuit in resin but that would get messy and expensive. 

Errata:

-button too close to headers when glue is applied

-remember space for audio in jack plug 

-the two columns of headers for the Arduino should not be continuous, also unclear what is first and last pin. Also they should be SMD headers. 

-don’t mess with RX and TX pins on the Arduino. 

-make a version with VGA plug?

-add text but have it cut onto plastic not made from metal

-audio offset thing doesn’t work

I also want to think about expandability, how could people take this project further by themselves afterwards ?

-Having a knob  or two knobs / LDR connected to an analog in on the Arduino…

-Be able to control the program based on voltage control levels at an input. This could mean it could even be attached to the polyphonic synth !

***************************************************************************

Here is the next version called the Spaghettini:

-It respects the height of the 50mm wide copper tape I have on hand.

-It makes more sense for the audio in cable to plug in at the side and not interfere with the capacitive sensor. 

-It uses curvy lines just for the capacitive sensing functionality and straight elsewhere which feels honest. 

-It has the ability to modify the brightness of any of the three channels, one at a time. 

-It has a potentiometer for analog in in adition the capacitive sensor. 

-I’m experimenting with different patterns on the left portion.

-The sensor works with the Arduino library CapacitiveSensor 

And here’s what it looks like all plugged in ! (But I need to add hot glue to make it really usable)

I have two goals for this project:

1. Finish the VGA video recorder board (with op amps, bias pots, bias for ADC) – DONE!
2. Make a version of the vectorscope image modification series but with a raster system taking the following image as the input – DONE :

1. Finishing the VGA Video Sampler board

For the first goal, I need to correct that last board I made:

Errata:

-The gain pots for the op-amp don’t work.

-I mixed up VCC (3.3V) and VCA (5V) in several places. (I just replaced the PFET with the LDO and manually rewired)

-The “EN” text next to the ADC was in the wrong place. 

-I forgot to tie down the reset of 74HC590 with a 10K resistor.

-The 74HC04 is labelled backwards, I put inputs on the right and outputs on the left for some reason.

Things appear to work with these changes:

It takes some knob fiddling but I can get an input sine wave digitalized. One definitely needs an oscilloscope to see what’s happening though.

2. Vectorscope image series

I can either load the image into memory by playing it on a computer screen and capturing the pixels, OR, loading the image into memory with a microcontroller. I’m not sure how big I should make the image, and what dimensions, if I load the image. 

Here is the p5.js code to take an image (called p.jpg) and print the red pixel value into a text document (called OUTPUT) with a comma and space seperator :

let img;

function preload() {
img = loadImage('p.jpg');
}

function setup() {
createCanvas(img.width, img.height);
background(220);
image(img, 0, 0);
let writer = createWriter('OUTPUT.txt');

for(var y = 0; y < height; y++) {
for(var x = 0; x < width; x++){
let pix = img.get(x, y);
writer.write(pix[0] + ', '); // takes RED pixel info, adds a comma and a space
if(!(y==1-height || x==1-width))
{
writer.write(pix[0]); // don't put a comma if it's the last element of the list
}
}
}
writer.close();
}

And here is the Arduino code to take this color information and load it into the memory space (90×90 max as PROGMEM has max 8,192 bytes max):

byte myChar;

#define IMG_WIDTH 90
#define IMG_HEIGHT 90
//data size=900 bytes
const unsigned char img [IMG_HEIGHT*IMG_WIDTH] PROGMEM={
17, 19, 19, 19, 19, 20, 20, 20, 20, 20, 21, 23, 23, 22, 21, 21, 22, 22, 21, 22, 21, 22, 21, 20, 21, 21, 23, 23, 23, 23, 23, 23, 24, 23, 25, 23, 24, 23, 25, 25, 25, 25, 25, 24, 25, 26, 24, 23, 25, 24, 23, 24, 25, 21, 20, 24, 24, 23, 20, 20, 21, 23, 22, 22, 22, 22, 22, 23, 23, 24, 23, 23, 23, 25, 23, 24, 24, 23, 24, 25, 23, 25, 25, 23, 25, 24, 24, 25, 28, 28, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 19, 35, 25, 32, 32, 26, 27, 17, 23, 27, 30, 33, 33, 35, 37, 35, 29, 30, 34, 37, 44, 26, 30, 65, 65, 57, 56, 55, 57, 59, 42, 38, 46, 38, 33, 40, 41, 43, 46, 35, 3, 0, 0, 0, 0, 1, 1, 0, 9, 49, 18, 0, 4, 0, 0, 0, 3, 2, 0, 0, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 3, 29, 231, 255, 245, 252, 250, 247, 248, 240, 245, 249, 255, 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1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 2, 3, 1, 0, 0, 0, 134, 255, 255, 69, 0, 48, 253, 255, 227, 17, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 3, 0, 0, 1, 1, 0, 1, 1, 2, 1, 1, 1, 0, 0, 0, 0, 2, 0, 0, 178, 255, 255, 119, 0, 1, 0, 0, 1, 2, 0, 66, 255, 255, 138, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 145, 255, 255, 84, 0, 49, 254, 255, 229, 19, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 2, 2, 2, 1, 0, 0, 0, 1, 1, 2, 1, 0, 1, 1, 1, 0, 0, 1, 0, 1, 196, 255, 255, 110, 0, 0, 0, 0, 0, 2, 1, 54, 255, 255, 138, 0, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 130, 254, 255, 76, 0, 39, 245, 255, 225, 13, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 0, 0, 2, 1, 23, 233, 255, 255, 82, 0, 2, 1, 0, 1, 1, 0, 61, 255, 255, 124, 0, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 142, 255, 254, 74, 0, 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66, 0, 1, 1, 0, 0, 1, 0, 128, 255, 255, 105, 0, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 152, 255, 247, 40, 0, 25, 232, 254, 119, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 174, 255, 255, 71, 0, 1, 0, 0, 2, 0, 0, 143, 255, 255, 106, 1, 0, 0, 0, 2, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 1, 153, 255, 250, 45, 0, 28, 235, 254, 142, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 190, 255, 255, 76, 0, 1, 0, 0, 0, 0, 0, 148, 255, 255, 122, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 152, 255, 248, 45, 0, 20, 244, 230, 45, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 117, 255, 255, 75, 1, 0, 0, 0, 0, 0, 1, 145, 255, 255, 94, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 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0, 0, 1, 0, 0, 1, 1, 0, 1, 23, 201, 237, 27, 0, 0, 0, 1, 0, 1, 0, 39, 240, 141, 0, 0, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 26, 206, 255, 45, 0, 37, 244, 255, 131, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 98, 255, 236, 27, 0, 2, 1, 0, 0, 3, 0, 34, 255, 255, 52, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 138, 255, 245, 39, 0, 37, 245, 254, 118, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 95, 255, 244, 32, 1, 0, 0, 0, 2, 1, 0, 55, 255, 255, 46, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 117, 255, 248, 39, 0, 33, 242, 255, 117, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 114, 255, 230, 21, 0, 1, 0, 0, 0, 4, 0, 51, 255, 255, 53, 0, 2, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 118, 255, 251, 43, 0, 29, 239, 255, 115, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 114, 255, 237, 35, 0, 1, 0, 0, 0, 5, 0, 45, 255, 254, 51, 0, 2, 1, 0, 1, 0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 125, 254, 254, 48, 0, 34, 242, 255, 116, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 2, 1, 3, 2, 0, 0, 1, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 2, 1, 0, 109, 255, 242, 36, 0, 1, 0, 0, 1, 2, 0, 51, 254, 255, 56, 0, 3, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 1, 0, 0, 2, 1, 0, 1, 124, 255, 246, 38, 0, 34, 245, 255, 111, 0, 1, 0, 0, 0, 0, 1, 0, 2, 2, 0, 0, 1, 4, 3, 7, 3, 2, 2, 1, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 108, 255, 218, 7, 0, 0, 0, 1, 0, 3, 0, 44, 254, 255, 50, 0, 0, 0, 0, 0, 0, 1, 1, 1, 2, 0, 0, 1, 3, 3, 1, 1, 3, 1, 1, 0, 1, 1, 4, 2, 2, 0, 0, 0, 0, 0, 0, 0, 128, 255, 243, 36, 0, 40, 246, 255, 157, 9, 23, 32, 30, 17, 29, 13, 0, 1, 0, 24, 61, 25, 0, 1, 0, 0, 1, 0, 0, 34, 32, 0, 1, 0, 1, 12, 6, 0, 2, 19, 22, 0, 128, 255, 240, 36, 0, 2, 1, 1, 0, 1, 1, 64, 255, 255, 64, 1, 10, 7, 10, 10, 16, 6, 0, 0, 0, 10, 35, 13, 1, 0, 0, 0, 0, 0, 0, 6, 8, 0, 0, 0, 0, 3, 8, 6, 7, 8, 2, 0, 150, 255, 248, 43, 0, 27, 229, 255, 255, 247, 242, 246, 243, 233, 254, 216, 46, 0, 43, 217, 255, 242, 61, 0, 23, 11, 18, 0, 94, 255, 255, 102, 2, 6, 121, 253, 228, 215, 220, 241, 250, 176, 197, 255, 255, 204, 6, 1, 0, 0, 2, 1, 8, 214, 255, 238, 243, 222, 230, 223, 225, 226, 255, 150, 0, 0, 49, 217, 255, 189, 22, 18, 37, 36, 41, 22, 75, 228, 250, 83, 0, 1, 44, 203, 245, 227, 226, 226, 224, 223, 249, 255, 251, 46, 0, 23, 231, 255, 254, 255, 255, 254, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 252, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 254, 255, 255, 255, 255, 241, 33, 0, 1, 0, 1, 0, 14, 224, 255, 255, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 255, 255, 255, 254, 255, 253, 254, 255, 255, 255, 255, 255, 254, 255, 255, 255, 255, 244, 39, 0, 10, 122, 153, 147, 144, 138, 142, 134, 131, 131, 138, 145, 136, 124, 122, 125, 139, 148, 151, 158, 139, 129, 143, 40, 74, 144, 135, 128, 127, 106, 109, 116, 106, 102, 99, 110, 117, 114, 97, 129, 96, 0, 0, 0, 0, 0, 0, 0, 102, 138, 112, 123, 116, 117, 107, 114, 131, 132, 140, 135, 135, 130, 112, 137, 86, 86, 118, 105, 101, 100, 108, 94, 93, 101, 103, 119, 120, 105, 100, 103, 102, 101, 99, 97, 95, 89, 83, 63, 7, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
// ARRAY OF PIXELS GOES HERE, COMMA + SPACE SEPERATED
};

void setup() {
pinMode (0, OUTPUT);
pinMode (1, OUTPUT);
pinMode (2, OUTPUT);
pinMode (3, OUTPUT);
pinMode (4, OUTPUT);
pinMode (5, OUTPUT);
pinMode (6, OUTPUT);
pinMode (7, OUTPUT); // PORT D

pinMode (8, OUTPUT); // WR PIN (inverted)


for (byte k = 0; k < strlen_P(img); k++) {

digitalWrite(8, LOW); // inverted so this puts WR HIGH (to read)
delay(10);

myChar = pgm_read_byte_near(img + k);
PORTD = myChar;

digitalWrite(8, HIGH); // inverted so this puts WR LOW (to write)
delay(10);

}
}
void loop() {
}

The github for this project :

https://github.com/merlinmarrs/tournesol

I’ve made the PCB for with the 74AC240 based on this design from http://www.smfr.org/robots/robot_images/dualsolarhead_schematic.png :

Hoping that it works better than the 540 version with the solar midpoint.

IT DOES! It is far more responsive and efficient and works with the solar panel! It has a funny quirk where it will first turn the wrong way then correct itself in one direction though…Next i’ll make it on a super small extra compact board and try the other circuit option:

It’s much more compact that the previous version. The photodiodes could be removed to make it even smaller. It took me around 25 minutes to assemble at a comfotable speed. By far the least efficient element of the assembly is the braided wire which is causing mini shorts :

There is already some interesting interplay with the two machines side by side…

3D model of fancy motor version:

Here’s a version with a tiny gear motor. The motor appears to lock up at low currents however so it doesn’t work super well. It’s also very difficult to attach the motor axle to the bottom platform. 

With the metal gearmotor it works much better:

And this version with the panels lower down:

Here is a tall version:

Here’s a compact design with a “flipper” arm:

The idea of pulling the solar panels from the board, exposing the electronics and creating the tilt naturally.

The little metal cap is actually a nice part of the look of the machine:

I have made the board thinner so that it fits perfectly over the gear motor:

Here’s a shot of it looking pretty:

Llama edition (it’s a heat sink). This photo makes me think I could have fun with shadows like in the 1970 Il Conformista film:

I see a monocled mustachioed Monopoly man here somehow:

This idea distributes the things to look at around the machine (one side has solar panels and the gear motor, the other has electronics and the underside gold lettering on the solar panels). When the machine is facing the sun we get to see the electronics. I guess the electronics is also sheltered from the heat of the sun a bit?:

Here are some feet ideas for the resin printer using small set screws and (in the right model) Pogo pins:

Here are two versions of the tripod design. One has the electronics as a backpack and hides it from the sun, the robot has two faces. The other has the “face” of the robot face the sun, in one photograph the whole robot is visible.

Version 1:

Version 2:

****

Side to side comparisons:

 Another idea for pogo pin feet using the crowned tips:

***

I made the barebones circuit in extra slim also:

debugging the previous version, it appears that the solar panels are indeed producing the expected voltage and current (2 x 1.67V, 18.4 mA), the voltage trigger and mosfet are working, the capacitor is charging, and the voltage to the motors is spiking. However the motors aren’t so much turning as twitching. The motors appear to be identical to others that are working however. Changing the capacitor from .22F to .15F changed nothing. 

EDIT:

I had another stab at this:

I noticed that the charging and triggering part of the circuit appeared to be working but that the motor was not firing. I assumed then that there was a soldering problem on the 74AC240 pins somewhere. I tested a copy of the same boards from the same batch to see if there were any problems with the etching itself, they all seemed good with no shorts and clean traces. I tested a blank 74AC240 as well and found that the only pins that were internally connected were 9 (Y1) and 10 (GND) – though I’m not sure why this is the case. I took a voltmeter to measure if there were any shorts between the pins on the IC and found that everything was mostly normal. Looking under the microscope it occured to me that the problem might be that the pins of the IC aren’t fully touching the pads below as they appeared to have been soldered quickly. In order to assume myself that everything was indeed well connected I reheated each of the pin connections and retested that I didn’t introduce any shorts. I then switched out the larger motor for a more efficient smaller DC motor. Testing with artificial light I now have normally functionality!

The second malfunctioning solar head has a different issue: It charges up fine from having no power and spins the motor no problem. But after a few times it stops triggering at hovers around 3.6V…I resoldered the connections and had the same issue. The voltage trigger appears to be triggering despite the voltage staying high. In the end I switched the bigger metal gearmotor for a small vibe motor and it worked just fine. I think I can conclude from this that the circuit I used is not suitable for the metal gear motors but works fine with smaller ones.

I am now looking into making this circuit even smaller using TSSOP-20 packages of the 74AC240 and maybe 0603 smd components too. I plan to make this double sided and to have the boards made at PCB way after testing a prototype circuit in the lab.

The circuit works fine after I had to resolder some of the IC pins to the pads (they seem to hover just above sometimes despite the soldering) and fixing a short between the two sides of the MOSFET by lifting up the positive side of the SMD cap up.

Testing with a single 3.4V panel and…it turns! I’m going to try to add the light detection now.

And this is how it could be integrated into the 2DOF design: 

This is a second option which would involve probably halving the above circuit and making it double sided. 

Another idea is to see how far this minimalism and miniturization can go, for instance with a single solar panel capable of charging up the cap to 3.3V ish. It could be 1DOF or 2DOF. Testing with the power supply with 4,46V @ 5,9mA it works no problem with the small gear motor. We’ll see if that’s the case with the actual solar cell soon.

Monocrystalline Solar Cell 24.5mW (4,46V Current – Short Circuit (Isc) 5,9mA)

https://www.digikey.fr/product-detail/en/anysolar-ltd/KXOB25-01X8F-TR/KXOB25-01X8F-DKR-ND/10127250

Monocrystalline Solar Cell 26.3mW 5.53V:

https://www.digikey.fr/product-detail/en/anysolar-ltd/KXOB25-02X8F-TR/KXOB25-02X8FDKR-ND/9990483

Here is what it could look like 1DOF:

…and 2DOF:

If the solar panels are a bit offset from the boards then the light sensors could be directly on the board and not need to be offset themselves from the board. 

****

I actually have one of these lying around to test the one panel idea (3,4V
@ 4,4mA): 

https://www.digikey.fr/product-detail/fr/ixys/KXOB22-01X8/KXOB22-01X8-ND/2754274

Here it is working! (remember that the “GND” side of the photo bridge actually connects to the ENABLE of the 74HC240)

some other panel configurations:

I could have the light sensors on either end. 

A little higher up…

Satellite inspired:

Here’s a quick 3D print:

Not even sure if adding another DOF will have a big effect, over the course of a day how much will it actually tilt up or down?…