Well took a week but I now have a complete system controller that can run up to 16 of these 72*24 LED boards. I designed it on saturday/sunday, ordered PCBs on sunday along with parts and just got the boards/parts today and put it together. So 6 days from design to finished unit. The unit is quite simple, it’s just a Cyclone 3 FPGA with some peripheral hardware.
There’s a 256K*36 bit wide SRAM for the frame buffer, two 16 channel LVDS transmitters to communicate with 16 LED display boards, a 16 jack ethernet panel, some regulators, a 40 pin “digital” input for plugging it into gameboys and such, power, programming and “user interface” connectors, and an NTSC/PAL/SECAM video decoder/digitizer.
The final goal of the entire device is a 144*144 pixel, RGB LED display with full 24 bit colour depth or as close to that as I can achieve realistically. I will first get some debug information working (the plasma again, then Conway’s Game of Life maybe, a real time Mandelbrot zoomer, and a Gameboy Colour will be attached. Finally, I will work on getting real live video input into it via the decoder.
This weekend I hope to get the LED controller communicating with one of the displays. After much debugging, I got the board to work I think. Quartus recognizes the FPGA and configuration ROMs, and I manually checked out the connections to make sure I didn’t have any shorts/opens and everything SEEMS to be a go. So now I will work out a simple serial interface via LVDS to communicate with these displays.
And now the fun part, pictures!
Some of the parts that go onto the board, along with the two bare boards (one front up, one front down).
End view showing ethernet jacks
Bottom view. The ethernet jack panel isn’t fully soldered, in case there is some issue that requires me to pull it. I don’t think it will need to happen but I’d rather not unsolder 128 pins if I don’t have to.