RS232 Question

Guest · Posted: Tue Aug 16, 2005 2:00 pm

I have a PIC18F452 and a MAX232 connected to PC RS232.

When I send data from PC to PIC it works fine. But, when I try to receive data from PC it doesn't work. It remain waiting forever in getc() function.

Im using:
#USE_RS232(BAUD=9600, XMIT=PIN_C6, RCV=PIN_C7)

Is necessary to use the MAX232 IC with PIC18F452 or can I connect it directly to PIN 2, 3 of DB9 connector?

I have verified the pin levels PIN_C7 is high and PIN_C6 is low.

Thank you.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Guest · Posted: Tue Aug 16, 2005 2:38 pm

Ok. thank you.

any suggestion to solve my problem ?.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

1. Check the connections in your MAX232 circuit.

2. Add the ERRORS parameter to your #use rs232() statement.
Example:

#USE RS232(BAUD=9600, XMIT=PIN_C6, RCV=PIN_C7, ERRORS)

Guest · Posted: Tue Aug 16, 2005 2:58 pm

I tried with my desktop instead of my notebook and it runs ok.
I guest that is related to the different volt levels to each other.

Does anyone has experience with that ?
Thak you

asmallri · Joined: 12 Aug 2004 Posts: 1635 Location: Perth, Australia