I am using the ATSAME54P20A (specifically the SAME54XPLAINED pro development board) and the ASF4 software architecture with Atmel Start. I have spent quite a bit of time working with this board, ASF4 and Atmel Start, but so far I have not been able to figure out how to configure a new serial port at run-time. Atmel Start makes it very easy to configure a new serial port and then use it at run time, but the configuration stuff is all implemented in #define statements, so if you want to set up an entirely new serial port, you have to build a new atmel start project and recompile the software, or once you understand how their preprocessor macros work, you can write the #define statements yourself, but still, all the configuration stuff is done at compile-time rather than run-time. I noticed that ASF4 implements some functions to allow baud rates to be changed at runtime, but as far as I can tell there is no way to configure an entirely new serial port at run-time using ASF4 short of reverse-engineering the ASF4 macros and implementing them in run-time code. I've been trying to hack the ASF4 drivers so that I can do that, but it's a big task, and I don't want to re-invent the wheel if I can avoid it. So do you guys know of a simpler way to configure a serial port at run-time, or do I have to continue digging into the ASF4 drivers and extend them to get this capability?