I’m building a hardware-accelerated RGB LED matrix panel display that you can hang on your wall. You’ve probably seen the 32x32 pixel matrix panels on Adafruit. My display is 128x64 pixels, and I run it at 12 bit color depth. I use a CPLD to convert a stream of SPI data into the parallel shift register format that the panels require. This allows me to use timers and DMA to free up most of the CPU time. I’ve made my firmware library compatible with existing matrix panel libraries’ APIs, so it should be easy to use.
Here are some pictures.
All my designs and code are open source, and available on GitHub. Click here for the backpack. Click here for the firmware library. I’m in the process of working out the last bugs in the firmware, finishing the mechanical frame, documenting what I’ve done, and writing applications that run on it. Please feel free to ask questions. I’ll be posting updates here and on Hackaday.io.
The frame rate is approximately 60 Hz. This is limited by the SPI bus bandwidth, which has a max clock rate of 30 MHz. You could sacrifice color depth for frame rate.
I plan to put a few up on Tindie once I have surplus hardware, and see where it goes from there. This will be one of the first places I post when that happens. I just got my Rev 2 version of the backpack from Macrofab tonight, so I’ll be putting it through its paces this weekend. Next feature is having the Photon update the CPLD configuration (no more programming jumpers).
I have quotes for a nice sheet metal frame. However, my mechanical engineer friend and I got sucked into 16 hour days at work for a couple weeks. Once I have a few more units assembled, firmware development will be easier. I’d love to sell some hardware at cost to firmware engineers who open source their code.
