Is there anything significantly different in the signals created by DMD2 that would cause this?
I've updated the firmware for an existing project that uses a cable between the custom PCB (ATmega386 based, essentially a Uno) and 4x DMD panels. The PCB and cable only transmit these pins:
- D13 SCK
- D11 MOSI
- D9 OE
- D8 SCLK
- D7 B
- D6 A
The existing firmware used a modified version of the DMD library, as outlined by @brissieboy elsewhere in this forum, and we have a 10k pulldown resistor on OE just like the DMDCON v1.1 schematic, so we can set the brightness of the DMDs.
I've updated the firmware to DMD2 and it works great if we use our custom PCB via a 16 pin ribbon cable, but connect via one of our cables and the DMD remains blank. Reverting to the older firmware based on DMD and it works fine through the ribbon or our cable.
Firmware using modified DMD: works on ribbon, works on cable. Tested OK on ribbon and cable up to 1m long.
Firmware usine DMD2: works via ribbon only. Tested OK on ribbon up to 1m long.
This is really puzzling. Any thoughts on what DMD2 might be doing that's different to DMD which could cause what we're seeing here?