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source= http://www.piclist.com/piclist/2003/09/29/151426a.txt?

Is the received character the same incorrect character, or randomly incorrect?

If you write a second character to the TXREG before the reg is available,
you will see this type of symptom also.

You may want to send the letter "U"
What type of debug environment do you have?  I found it was much easier to
debug when I received characters by the PIC, and wrote the incoming bit
pattern to a bank of LEDs.  If the clock is too fast or slow, the bit
pattern has characteristic changes that are easy to see and recognize.  I
used an RC circuit, and it was easy to see if the values were at the edge
of tolerance, because the bit pattern would be unstable.  When the RC
values were sufficiently in tolerance, everything was very stable with the
RC circuit.

There is a set of characters that are very useful when doing this
debugging:  ^A, ^B, ^D, ^H, ^P, space, "@"

Try to set the parity bit to "mark" and see if the occasional second
character disappears.

Write better notes in your lab book, and disclose those details when asking
for help.

Are you fluent with a scope?  Set it to trigger on the stop bit.
Send the character sequence above.



......
Chas. K. Roberts wrote:

I am trying to write a byte from the PIC to the PC on the USART. But
when I write a byte to TXREG the byte received at the PC is always
incorrect, and sometimes the PC reads two bytes. I am using a MAX232 to
do the level conversion and I am confident that the USART is set up
correctly. What are some possible causes for this?

Charles K Roberts II
ORNL-SNS Project




- ---
Aubrey  McIntosh
http://www.piclist.com/member/AM-vima-Y84
PIC/PICList FAQ: http://www.piclist.com


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