Fixed the uart stuff!

A project log for Thumb Term

Battery powered Linux-terminal handheld with front and rear inputs, 4.3" DSI LCD, a Pi 3A+, and GPIO breakout. WIP.

dan-a8ksh4Dan (a8ksh4) 09/04/2023 at 05:120 Comments

I posted previously about some display flickering, and I was having trouble getting the UART connection between the Pico and the Pi 3a working.  With Ubuntu on the Pi 3, when I had the UART wires connected, the system would flash the display and not boot.  I changed the OS to Raspberry Pi OS and it would boot normally, but I couldn't receive anything from the Pico.  I kind of got frustrated with this and took a few weeks off from working on it.  

I explored the idea of using I2C instead of UART, but I2C slave functionality isn't really supported by MicroPython.  I talked to my guru a bit and troubleshooted by hooking up a USB UART thing to each device separately and found that the pi 3 was working normally but the Pico had no TX!

I was able to move the wires that were controlling the system power and pi LiPo shim and free up an alternate set of UART pins and everything is working now!!  A basic keymap and it's printing some characters on the screen.   

This is where I'm at now.