Definition of Ur from Oxford Dictionaries :
primitive, original, or earliest.
“urtext”
denoting someone or something regarded as embodying the basic or intrinsic qualities of a particular class or type.
“ur-thespians Patrick Stewart and Ian McKellen”
Reading about cave paintings and ancient sculpture I am realizing that my exploration into the 1970s computer architecture is a kind of fascination with urcomputation.
The eternal question for my project has always been what is being fed into the machines, what it is rereading or rewriting ? Perhaps the answer could be urmedia – ancient art works.
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This machine should not try to be something it’s not. I want to exploit the potential it offers, low level memory manipulation, rather than get lots in technical challenges that aren’t sui generis to the device.
In some way I feel like I’m coming full circle back to these plotter experiments mixing text, fill, and contour that include glitches of the rendering process :
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This classic Ti watching hippo hunt :
I love the background patterns – the vertical reeds and the underwater diagonal pattern – with people and creatures superimposed.
A nice article about simulating traffic with a simple processor and clever tricks : https://pizzalegacy.nl/blog/traffic-system.html
Main tricks : having tiles encode the direction of traffic, cars that go off screen simple respawn on the other side, car speed is fixed based on pixel draw rate, simple test to see if collision next pixel and if so delay for 10 pixels. Tiles are made in such a way that advancing halfway through the tile and then drawing the new car in the subsequent direction of the next tile to complete a 90° turn will always work.
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I’ve got horizontal image doubling. Basically, once I reach halfway, I subtract half the screen so it starts drawing again from the left.
if(h_count == 200) begin
h_count <= h_count - 200;
end To wiggle horizontally an image (doesn’t work vertically):
h_count <= h_count + 1 + sine;To draw a grid over the screen :
if(h_count%20 == 0 || v_count%10 == 0) begin
r_out[0] = ~b[7];
r_out[1] = b[15];
r_out[2] = b[31];
endI discovered that the frame from the rpi is actually 400 x 300 and not 800 x 600. This means that I can record two sets of collages and switch between them (can create mini animations like this) :
if(key[4]==1) begin
addr <= (h_count>>1)+((v_count>>1)*400);
end
else begin
addr <= 30000 - (h_count>>1)+((v_count>>1)*400);
end******
Preparing the NO SCHOOL 2026 board. It has to be around 20 euros and I have to make at least 20 of them, so they can’t be too hard to make !
It should output VGA and ideally take an input (VGA, or video from a camera ?). It would be great if it was both a sampler/synth and the VGA trainer board for low level video experiments. The protoboards are expensive though so I’ll probably set it up so it uses an existing protoboard that isn’t integrated into the board.
FPGA Ice40………….6,64 € (for 25+)
Keys………………………1€/piece
OV7670…………………5,01€
VGA female…………..1,22 € (for 25+)
Optional things :
atmega328……………..2,00 €
small SRAM……………1,22 € (IS62C256AL-45TLI-TR)
To fix from the VGA trainer board, I cannot use male headers for connectors ! I’ll need something much more durable like screw terminals (Pluggable Terminal Blocks which are around 30 cents for a two position).
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Super understandable verilog implementation of OV7670 camera with the Nexys 4 DDR FPGA (15K LUTs) : https://github.com/westonb/OV7670-Verilog/tree/master
To build this in IceCube I had to start with the file which references the other modules (camera_configure.v) and then I compiled and added each dependent file as it came up as an error. Compiling all of this (minus camera_read) uses 497 or 1280 LUTs. I then added camera_read.v as a module.
Some things I learned from looking at the verilog :
- it uses a ROM to store the OV7670 16bit commands.
- it uses a Finite State Machine to mode between different states (idling, sending, receiving).
- In the hierachy of the files, after camera_configure, OV7670_config.v is at the top, and it uses OV7670_config_ROM and SCCB_interface to store the commands and handle the low level tasks of each message send respectively.
- Once the initialization is complete the done signal is activated. I’ll need to use this to enable frame reading only after the config is complete.
Next would be to add a BRAM to put the down-sampled recorded pixels here and a VGA video output. Some things to keep in mind, it works with a 25MHz clock, the breakout board includes 4.7K resistors pull-up resistors from the SIOD and SIOC pins on the camera to the 3.3V supply, and the author includes a reminder that not every pin on the FPGA can act as clock input (for the PCLOCK coming from the OV7670 in this case). I think the correct type of pin for a clock input is a GB (Global Buffer) pin of which there are 8 in total.
The idea is to now make a test board where the MIT verilog could be tested along with two other options : an atmega328 which I would have to program in-situ, and connections for an Arduino (giving the partipants the ability to also change the camera configuration but requiring everyone to have an Arduino to get the thing functioning). After testing I’ll be able to design a final board that may or may not have all three options.
EDIT : Too lazy to make the atmega328 version and I like that the Arduino allows people to change the camera parameters easily. If all goes well, I’ll make a next version that maybe has SRAM and other features. Because I can understand the MIT 6.111 class FPGA verilog I’m going to add an SD card to this board to see if I can make that work as well (and will take advantage of having Arduino there to also make it work the SD card if the FPGA verilog doesn’t work). This would let me test if I can do away with the rpi and either make my own compressed video put onto an SD card (which would go far to making this a “stand-alone” device), and to test if the camera is an even better solution to produce input video on the fly.
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In parallel I’ve been looking in to stand alone media players that output VGA. But it costs 30 euros. Another option would be to get rpis super cheap (can’t find less than 20 euros) but then I have to worry about the rpi version and go through that pain again…
Other options :
- Read a special format on an SD card (MIT simple SD card reader verilog : https://web.mit.edu/6.111/www/f2017/tools/sd_controller.v)
- ESP32 outputting video from SD card.