I'm working on a custom SAMD51 board similar to Adafruit's Metro M4 or Feather M4 and I need to move a few pins and serial ports around. Though when I try to change the pins used for Serial1 my program gets locked up in a cortex_handler.c empty function called Dummy_Handler. From what I can gather this may have something to do with the interrupt routines that Arduino's Serial implements, but I'm not sure how or why exactly this wouldn't be working. Looking up the call stack the program is interrupted during a delay inside the Arduino Serial library. Even stranger when modify the variant file similarly and compile for Sparkfun's SAMD51 Thing Plus I'm able to print to Serial1 with no issues.
I'm able to initialize Serial1 just fine with something like Serial1.begin(9600); though when I attempt to print or write I'm pushed to the Dummy_Handler.
Currently I'm trying to use SERCOM0 on pins PA08/PA09 and I have also tried SERCOM4 on PA12/PA13 with the same result. Does this sound familiar to anyone and is this Dummy Handler loop a generic fault?
I can share my variant files and anything else that could help if this is potentially helpful - thanks.