Not familliar with the CCS compiler, but just as a thought, its serial comms
library dosen't use pin B4 for flow control does it?

Cheers

Mike

> -----Original Message-----
> From: Johan Fredriksson [SMTP:infinity@TELIA.COM]
> Sent: Monday, July 17, 2000 1:25 PM
> To:   PICLIST@MITVMA.MIT.EDU
> Subject:      PIC hangs on I/O operation
>
> I've tried this on 12C509A and 16F877 with the same result. I'm just
> looping
> forever reading two pins and sending a text on RS-232. I'm using CCS
> compiler for coding.
>
>    while (-1){
>       if (INPUT(PIN_B3)){
>          printf("B3 High\n\r");
>       } else {
>          printf("B3 Low\n\r");}
>       delay_ms(250);
>
>       if (INPUT(PIN_B4)){
>          printf("B4 High\n\r");
>       } else {
>          printf("B4 Low\n\r");}
>       delay_ms(250);
>    }
>
> Pin B3 gets a logic 1 (4.95V) or 0 (0.01V) and pin B4 is always high. The
> input to B3 comes from a Hall-effect switch. When it detects a magnet it
> gows low and when magnet is removed it goes, of course, high again
> (pull-up
> to +5V and the Hall acts like a transistor driving to ground). The logic
> output is OK all the time.
>
> When removing the magnet so it goes high again the PIC is dead. But not
> compleatly dead! If I add the magnet again so it goes low the PIC
> continues
> from where it was again.
>
> Anyone having some hints or ideas? I'm very confused now :-)
>
> /Johan
>
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