Quote Originally Posted by HenrikOlsson View Post
... As soon as the USART is finished sending the character the interrupt fires again and the process repeats.
This can be very tricky and lead to an endless loop of interrupts in case you do not have to send something for a while.

I never had a reliable Tx Interrupt routine although Darrel was more than helpful when I was trying to make a succesful Tx Int Routine.

Ioannis