Started by Andrew Ness June 14, 2006

I've followed the directions in SPRA661 to implement a software UART using
the McBSP port 0. I am using a C5416 device and modified the included
assembly slightly to allow for using a far memory model. Things work okay
for the most part, but I am experiencing parity and framing errors every now
and then when transmitting to the DSP. Sometimes I can transmit 100 or more
characters without a problem but sometimes the errors occur more frequently.
Initially I was operating the DSP at 160MHz and the UART at 57600 but then
tried operating the DSP at 32MHz and the UART at 9600 with no improvement.
I'm using a very short cable to the serial port of a PC so there shouldn't
be any signal integrity issues there. I tried one PC running HyperTerminal
under Windows 2000 and another PC running minicom under Linux - but the
computer used made no difference. I used an oscilloscope to make sure that
my calculated DIV value resulted in as close as possible to the desired baud
rates - at 9600 I had only a 0.2% difference.

I'm hoping someone has experienced this before and might have some


Andrew Ness