CCS :: View topic - USART is not working. Please Help!!

FAQ

Forum Help

Official CCS Support

Profile Log in to check your private messages Log in

CCS does not monitor this forum on a regular basis.

Please do not post bug reports on this forum. Send them to support@ccsinfo.com

USART is not working. Please Help!!

CCS Forum Index -> General CCS C Discussion

View previous topic :: View next topic

Author

Message

PCM programmer

Joined: 06 Sep 2003
Posts: 21708

Posted: Sun Apr 09, 2006 10:23 pm

Quote:

There is an option called "INVERT" that will allow your PIC to talk
directly with a generic COM port (in this case on the PC) without
any true RS-232 level convertors.

If you do this, you should put a resistor between the Tx pin of the
DB-9 on the PC (pin 3) and the Rx pin on your PIC. That's because
the RS232 driver in your PC puts out levels of about +/- 10v.
Your PIC has clamp diodes on the i/o pins to protect against voltages
that go below ground or above Vdd. The resistor will limit the amount
of current going through the input clamp diodes on the PIC to a
safe level, so they don't burn up. If they do burn up, at a minimum
the PIC input will likely be destroyed.

Look at the schematic on this page:
http://www.rentron.com/PIC16F84.htm
(Scroll down a bit to see it)
Notice the 22K resistor between the RS232 connector on the PIC and
the Rx pin (RA4 in this case) on the PIC.

UFAnders

Joined: 13 Apr 2005
Posts: 36
Location: Michigan


Posted: Sun Apr 09, 2006 10:31 pm

Yikes! You learn something new everyday - Guess I'll be putting a few resistors in my boards...

Display posts from previous:

	CCS Forum Index -> General CCS C Discussion	All times are GMT - 6 Hours
Page 1 of 1

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum