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glueless RS232 interface to SPORT0 on 21065L

Started by robmcgurrin October 23, 2006
Hi all,

I'm trying to implement a glueless RS232 interface to SPORT0 on my
21065L. My code is based on the ee-191 engineer to engineer
note, "Implementing a Glueless UART Using The SHARC DSP SPORTs ".
I've tied the RFS0 and DR0A pins together. The problem is that the
SPORT will occasionally lock up while receiving data from a PC over
the RS232 interface. I have to reset the SPORT to start receiving
data again.

I've reduced the application to a simple loop in main that polls the
SRCTL0 register for a "not empty" condition and reads the RX0A
buffer. I send in a bit stream from the PC and the SPORT will lock
up after several seconds.

Just as a test, I set the RFSR bit to 0 in the SRCTL0 register to
ignore frame syncs after the initial one. The SPORT will run
indefinitely. This leads me to the conclusion that there maybe
something wrong with tying the frame sync input to the receive input
and that there may be some sort of timing violation that causes the
SPORT to lock up.

Have you heard of this or any other similar issue?

Thanks,
Rob