On 21/06/2010 21:27, Isaac Marino Bavaresco wrote:
> I was getting really weird behavior from a PIC16F648A:
>
> The serial data out was available at both RX (RB1) and TX (RB2) pins.
> At first I suspected that both pins could be shorted together outside of
> the chip, then I noticed that the RX pin signal was inverted.
> Very odd, because I don't have any inverter on the board, not even a
> transistor.
>
> After too much fuss (even cutting tracks and removing components), I
> found that I had the RX and TX pin directions reverted (TRISB register).
> Then I corrected the pin directions and everything worked OK. It is
> worthy noticing that bit CREN at RCSTA was turned off also.

I would be interested to know what values you ended up with for TRISB1 =

and TRISB2.  The following comment is taken straight from the datasheet, =

page 80:

"TRISB<1> and TRISB<2> should both be set to
=911=92 to configure the RB1/RX/DT and RB2/TX/CK
pins as inputs. Output drive, when required, is
controlled by the peripheral circuitry."

I noticed this for the first time yesterday when setting up USART on an =

18F, but it appears to be the same for the 16F648A too.

Perhaps this is related to the problem you are having and maybe =

following that advice would be the best.

David
-- =

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