RAK4631 on 19003/19007 Serial configuration

pierluigi.rotondo · November 24, 2025, 9:04am

Hello,
I recently bought some RAK4631 on the 19003 AND 19007 WisBlock base boards, pre-flashed with the latest version of the Meshtastic firmware by RAK.

For the 19007, Serial communication over USB worked out of the box.
For the 19003, when I connect the boards via Serial port over USB to Windows 11 and Raspberry PI running Debian, I don’t get any communication. Client side I have same machines/configuration as the working device above.
So the main issue is that the 19003/4631 does not communicate via Serial port.

On the non-communicating 19003, I enabled Serial, forced baud rate to 38400 (same on the client side). I have the option to specify RX and TX pin, but what are the exact pin for Serial RX and TX?

carlrowan · November 25, 2025, 6:27pm

If you have RAK19003 ver D or ver E boards, then you must use pin 19 and 20.

You can use setup to see messages via UART.

Btw, if this is the same board that hangs up on USB serial logs, I am not sure if your UART output will work. USB is the best way to capture logs from meshtastic nodes.