Same as in the main code.
Use Timer1 as baudrate generator.
Timer1 can be programmed to have the same accuracy and deviation as
Timer2, up to 115200 at F_SYS = 125 Mhz. See comment
setup_serial_timer1() comment for valid baudrates and settings.
Timer1 is used in 8-bit auto-reload mode.
Only differance is that the serial is transmit only and poll-based so no
interrupts are used to transmit data.