On the Hunt for a Serial Problem

[jblanked]

@ernst

You can not use GP4,GP5 because these pins are connected to the PicoCalc onboard PSRAM.

@Daren

If the Flipper and Psion only worked one way same as picocalc I’d be less puzzled, I have tried multiple times and the results are the same, it isn’t something that I need to get working so I doubt that I will spend much time trying to get to the bottom of it, but I did think it interesting after reading this topic where the Picocalc was receiving but not sending, and my findings were the opposite with the Psion.

Try flashing Picoware and using the Serial Terminal app. It uses GP4 and GP5, and I did my testing with the PicoCalc (using the Serial Terminal app) and Flipper Zero (using the UART Terminal app)

builds/MicroPython/apps_unfrozen/Serial%20Terminal.py

[Toml_12953]

I use GP4 and GP5 for COM2: since they are brought out to the external connectors. There’s no problem at all. No hardware mod needed. Instead of relying on schematics, try these things yourself.
OPTION SERIAL CONSOLE COM2,GP4,GP5,BOTH

[ernst]

You are correct that GP2-GP5, GP21, GP28 are connected to J703, but these lines are also connected to U301 (ESP-PSRAM64H). GP8/GP9 are listed in the diagram with UART1, meaning no other function. I don’t know whether U301 survives the voltage levels produced by an RS232 adapter, with GP8/GP9 the only damage would be a Pico board that can be replaced in a short time at low cost, replacing the PicoCalc (if damaged) would be more problematic.

I am normally very careful giving advice, I do not want to be responsible for possible damage.

[Daren]

Thanks @Toml_12953 @ernst @jblanked for the input and advice, it seems that serial comms is a bit of a minefield currently with Picocalc and Picomite, I saw a video where it was said that the two dip switches configure some routings of the UART pins to either the STM32 or the Pico, but that doesn’t seem correct?