Darwin Hawes (hawes@physics.ubc.ca) wrote:

>I am using a windowed PIC16C56 with a 32kHz oscillator.  The power
>drawn when the window is open is a nice 15uA, but when I put a piece of
>black electrical tape over the window, the current consumption rises by
>a factor of 20.  Does anyone have any idea why this is happening?  All
>unused pins are grounded or pulled high.

Darwin:

Aaron had a good suggestion -- it's likely that you've failed to
initialize some registers, so your code isn't behaving properly when the
window's covered -- but the code he showed was for the 16C57.  For your
16C56, use the following:

        USEFSR  EQU     0
        FSR     EQU     4
        PORTA   EQU     5

                MOVLW   PORTA   ;PREPARE TO ZERO ALL REGISTERS EXCEPT
                MOVWF   FSR     ;THE FSR, RTCC, PC, AND PROCESSOR STATUS
                                ;REGISTERS.

        CLRRAM  CLRF    USEFSR  ;ZERO A REGISTER.

                INCFSZ  FSR     ;HAVE WE DONE THEM ALL?
                GOTO    ZEROEM  ;IF NOT, LOOP BACK AND ZERO ANOTHER.

-Andy


--
Andrew Warren - fastfwd@ix.netcom.com
Fast Forward Engineering, Vista, California