I would like to use the two USARTs in the ATtiny1634 so that GPS messages are read in on one port and output unchanged on the other port. On the port that repeats the GPS messages I want to inject other data calculated in the Tiny.
Also, the Tiny will send configuration messages to the GPS and receive confirmations from it.
I would like to code this in assembly.
Any suggestions where to begin? I did set up a UART many years ago on ATmega8535 (if I recall correctly).