Another issue you should consider is what happens for sustained data transfers in each direction. Either of the two devices sending data to the MSP COULD have a data rate very slightly higher than the MSP. What happens when there is data the MSP has received on one UART but cannot send out the other because it hasn't finished sending the previous byte?
One method to consider is running the UART at a data rate that is very slightly (1%-1.5%) higher than specified. The idea is to make the transmission of a data byte slightly faster than the reception while still ensuring robust reception by all. Another is queueing the data in a buffer large enough to hold burst transmissions. Unfortunately the overhead required for queue maintenance may be too much for the MSP at the required data rates. A third is to require the incoming data to be formatted with two stop bits but to send outgoing data with only one. I'm sure others on this list will have additional solutions. Regards -Bill Knight R O SoftWare
