Jan-Erik is on to something here.  Serial communications is easy once you
get it working, but getting it working can sometimes be tricky, and without
a scope it's tricky and you are blind.

Step 1 - Like J-E says, make a LED blink at a rate you can explain.

Step 2 - Set up your serial port for 300 baud, and send a 00 once every 10
seconds.  You should be able to see this with an analog meter or LED and
stay convinced that the timing is what you think it is (although you still
aren't confident of the baud rate).

Step 3 - Send 300 - 00's in rapid succession at 300 baud, then wait a long
time (20-30 seconds) before doing it again, one start bit, one stop bit.
The output line should go low for about 10 seconds each time, long enough
for you to measure with a LED or analog meter.  (10 bits per character, 3000
bits=10 seconds, OK, OK, one of the 10 bits will be high, but probably you
won't see that without a scope).  This gives you some confidence you are in
the ball park for baud rate.  Change your 00's to AA's and the LED should be
about half brightness or the meter about half voltage.

Step 4 - Hook up Hyperterm at 300 baud and see if you can make anything
sensible happen.  If you have trouble, then either your Hyperterm settings
are wrong, you have a problem in the cable, or the timing is off.  But at
least now you know it can only be a little off.

Step 5 - Now move to 9600

--McD

----- Original Message ----- 
From: "Jan-Erik Soderholm" <jan-erik.soderholm@telia.com>
To: <piclist@mit.edu>
Sent: Monday, May 02, 2005 9:15 AM
Subject: RE: [PIC] USART async comms with PC running hyperterminal, problems


> As othes have said, time to step back.
> Make a LED blink at a known speed to verify
> your osc settings. Then go forward to the uart code.
> With the lack of tools (o-scope), it's har to do in
> any other way.
>
> Jan-Erik.
>
>
>
> -- 
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>


-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist