Wednesday, September 22, 2021
I was able to get some semblance of a display using the Atmega 328, an 8 bit device, but there were color issues, and some random light twinkling. I had anticipated this but didn't plan very well for it when I made my last MCU board with ability to swap in a 32 bit Teensy V3.2 MCU for the Atmega MCU. The idea was sound but my random selection of digital pins was bad and a simple swap just did NOT work.
Biggest issue? O/P of Teensy is 3.3 volts, not the logic 5 volts I was getting with the Atmega, so I would need level shifters. I made a couple dongles with the required logic and drivers and after proving they worked, I re-made the MPU board using ONLY the Teensy (not Atmega), but with the level shifting logic. This was MPU board #4.
I purchased a board made by PixelMatix that is used with a Teensy and the Adafruit Matrix Panel, and mimicked it for the logic. I liked the idea of using flip-flops (74HC374) to determine when to write to the rows.
In the photo above, the two green PCBs are "dongles", used with "old" logic board to test the system. After confirming it worked, I merged the two green boards with the red one to make the FINAL PCB (below).