Mode good progress on this today.
After probing around the 19003 I found that it’s TXD1/RXD1 are actually connected to UART1 on the RAK4630.
After digging deeper I found that I was using version E of the RAK19003 base board. On this version of the board they changed what was connected to J7 from UART2 to UART1.
It’s very frustrating that I can’t find any documentation for version E.
Anyway, I tried assigning pins 19/20 for the GPS pins and it still didn’t work. But when I changed the serial interface in /firmware/variants/rak4631/variant.h then it started working!!! See the change below.
/*
* Serial interfaces
*/
#define PIN_SERIAL1_RX (19)
#define PIN_SERIAL1_TX (20)
So that is great news but the question I have now is, why didn’t it work when I changed the GPS pins in the settings? Also, is there an easier, better way to solve this pin reassignment that doesn’t require building custom firmware?