Two thoughts:
If the USART is working, then presumably the clock is still correct. If the clock changed then the baud rate would change and you would not be getting good data out of the the USART.
So, do you have other interrupts running that are taking a lot of processing taime, and make the main program appear to be running slower?
Another option is to route the Clock to an I/O pin and check the clock with an O'scope, or a frequency meter.
JC
↧