andyteleco wrote:

>Hi, I'm writing some routines to read a DS2411 (serial number) chip using a
>PIC and to send the data to a PC via a DIO card. The communication with the
>chip is perfect and the number is read, but I can't send the data to the PC
>since I want to use RB3 as a strobe signal and for that I need to set
>TRISB(3)=0, which I can't achieve (TRISB stays at the same value after
>writing on it). I'm using an MPLAB ICD2 with the PICStart Plus programmer.
>The communication fails both on programmer and debugger mode.
>
>This is the part of the code that fails:
>
>
>
>MAIN:
>BSF STATUS,RP0 ; Select Bank 1 of data memory
>MOVLW 0x47 ; Initialize TRISB
>MOVWF TRISB ;
>BSF PORTB, 3 ; Strobe=1 ERROR!!!!! TRISB stays at 0xBF
>
>  
>
Hi,

In addition to Herbert's comments I found one bug (did not look for 
others) in your code:

MAIN:
BSF STATUS,RP0 ; Select Bank 1 of data memory
MOVLW 0x47 ; Initialize TRISB
MOVWF TRISB ;
BSF PORTB, 3 ; Strobe=1

After you set TRISB you forgot to switch back to bank 0 before the BSF PORTB,3 command. Forgetting to put your code in the correct bank can cause all sorts of strange operations.

Your code should look like:

    MAIN:
    BSF STATUS,RP0 ; Select Bank 1 of data memory
    MOVLW 0x47 ; Initialize TRISB
    MOVWF TRISB ;
    BCF STATUS,RP0 ; Select Bank 0 of data memory
    BSF PORTB, 3 ; Strobe=1

Hope this helps.

Chris

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