Well I now have the Raspberry Pi talking to an Arduino using the UART. I’m seeing my hello-world message popping out at the far end … mostly. It does seem to drop a character in a regular point, but that is probably a script issue.
I’m not echoing back the data yet but I guess that will work fine.
So technically I can send a message to the Arduino and then signal that to the OLED display.
I still a bit bemused that I can’t use the Pi’s GPIO pin to talk directly to the OLED display, even though it is using the same functions as the Arduino.
Still, it is progress.