strange int behaviour

[Darrel Taylor]

Hi tom,

The 16F876 has 8K of program space.

PBP automatically inserts an Interrupt "Stub" for you if the program space is greater than 2K. Why?, I don't know. The "Stub" is identical to what you have at the beginning of "myint", and it's all done before getting to "myint". Then once in "myint" it tries to save them again, but now the registers have been modified. When they get restored after the interrupt, something will have the wrong value, affecting the main PBP program.

By testing for the code size first you can avoid the problem. Or, since you know the code size is larger than 2K, you can just leave that part out entirely.

    IF (CODE_SIZE <= 2)
        movwf   wsave 
        swapf   STATUS,W
        clrf    STATUS
        movwf   ssave
        movf    PCLATH,W
        movwf   psave
    endif