I have two different development boards, one is a M68DEMO908GB60 with a MC9S08GB60 micro, and another home brew board that has a MC9S08GT16A installed. I have written a simple program to transmit a three byte data packet about once a second via the SC1 port simulating a MIDI (musical instrument digital interface) message. I am able to monitor the raw data using a MIDI interface and a MIDI monitor utility running on a PC. The baud rate is configured at 31.25K and uses SCI1. The same is code running on the two different boards. While the messages are completely in tact from the GT16A home brew board, the data from the GB60 appears to periodically lose synch and produces an erroneous output in the monitor app. It is as if the bus clock is periodically changing and thus temporarily changing the baud rate. I have disabled the COP system thinking it may have been causing a system reset, but this has had no effect. Initially I thought the GB60 demo board might have a hardware issue causing the problem, but I have another completely different SBC that happens to utilize the GB60 and produces the same intermittent synch problem as the other GB60 board. I believe the GB60 and GT16A to be essentially the same core with only differences in available I/O. Am I missing something?
Thanks in advance for any input!