I finally gave in and bought a 16 x 32 LED Matrix panel from Adafruit - it was expensive, but so many LEDs! In order to try it out as soon as possible, I hooked it up to a digital waveform generator (DWG). Following the timing diagram by JaySissom, I wrote a script to generate 16x32 images. Here is a scope capture of the CLK (blue), OE (pink) , and LAT (green) signals for generating a single 'line' of the matrix (a line is actually 2 rows of LEDs):
I connected my DWG to the panel via a flying lead cable, 12 connections in total = 6 data lines, 3 address lines, and CLK, OE, and LAT:
The next thing you know, we have color!
Solid colors are pretty straightforward, but it was nice to be able to test and tweak my PWM code before writing any VHDL. I took some video of the setup and the PWM code running. I used Favicons (16x16 web browser icons) as a quick source of test images. Check it out:
The next step is see how fast I can push the clock, and to measure how much power the panel consumes under different conditions.