Hello

This is a sample of a program that is not working. I want to read a
potentiometer and display the results via LED s. The program displays the
results, but the overflow does not work. The LED display 255, then appear to
roll over. It should read a max of 250. I have tried 8 variations without
success. Could someone please tell me what I am missing. I can sleep when I
can't solve a problem.

Thank you

Nichole

#INCLUDE <16C84REG.H>
             TITLE "MEASURE POT ON LED, SHOW OVERFLOW=250"
             LIST P = 16F84
;            FILE NAME POTCAL8.ASM
;            Clock = 4MHz -> 1 instruction takes 1us
;
PULSE1          equ    0Ch              ; pulse time high CNTR
PULSE2          equ    0Dh              ; pulse time high CNTR
HB              equ    0EH              ; Heart Beat High
BUTC            equ    0FH              ; button loop cntr
PULSE1S         equ    10h              ; pulse time high STORE
PULSE2S         equ    11h              ; pulse time high STORE
DELAY1          equ    12h              ; 1 ms count
DELAY2          equ    13h              ; # ms /4 of low time
DATAPRT         equ    14H              ; data port
CTRLPRT         equ    15H              ; control port
BUT1FLG         equ    16H              ; button 1 pressed flag
BUT2FLG         equ    17H              ; button 2 pressed flag
BUT1CNT         equ    18H              ; button 1 COUNTER
BUT2CNT         equ    19H              ; button 2 COUNTER
PULSE1PS1       equ    1Ah              ; pulse time high STORE
PULSE2PS1       equ    1Bh              ; pulse time high STORE
PULSE1PS2       equ    1Ch              ; pulse time high STORE
PULSE2PS2       equ    1Dh              ; pulse time high STORE
;********************************************************************
;*******************************;
;       MAIN ENTRY POINT        ;
;*******************************;
        ORG 0X000
        GOTO START
;*******************************;
;    INTERRUPT SERVICE CODE     ;
;*******************************;
        ORG 0X004
        RETFIE                  ;return from interrupt
;*******************************;
;       SETUP PORTS Etc.        ;
;*******************************;
START
        MOVLW  B'10000111'
        OPTION                  ;set up the OPTION,Disable Bpullup
;
        MOVLW  B'00000000'
        MOVWF  0BH              ;Set up the INTCON register
;
        MOVLW  B'00000000'
        TRIS   PORTA            ;setup port A BITs 0-3 as OUTPUT
        MOVWF  PORTA            ;clear port A
        MOVLW  B'00000000'
        TRIS   PORTB            ;setup port B BITs 0-1 as output
                                ;*******************************;
                                ;       FIRST  SERVO            ;
                                ;*******************************;
BEGIN   MOVFW  PULSE1S          ;LOAD Pulse Store
        MOVWF  PULSE1           ;LOAD Pulse DISPLAY
        MOVWF  PORTB            ;DISPLAY PULSE1 8 LED=COUNT IN b'
                                ;***********************************;
                                ; READ POTS B0-B1                   ;
                                ;***********************************;
        MOVLW  B'00000000'
        TRIS   PORTA            ;setup port A BITs 0-1 as output
        CLRF   PULSE1S          ;Clear previous value
CAP_C   BSF    PORTA,0          ;START CAPACITOR CHARGE
        NOP                     ;Time to charge
        MOVLW  b'11111111'      ;Set PortA,0 to input
        TRIS   PORTA            ;Teach portA
MEAS1   CLRWDT
        BTFSS  PORTA,0          ;Test A0 skip if 1
        RETURN                  ;
        INCFSZ PULSE1S,F        ;Inc pulse1s skip if 0
        GOTO   MEAS1            ;
        MOVLW  0FAH             ;LOAD MAX PULSE=250
        SUBWF  PULSE1S, w       ;Subtract current value from it
        BTFSS  STATUS, C        ;If carry = 1, result is positive
        GOTO   BEGIN            ;No it is not -> goto down
        MOVLW  0FAH             ;Load Maximum Pulse Width
        MOVWF  PULSE1S          ;Store it in the position Value location
FINAL   GOTO   BEGIN            ;restart the MAIN Programme loop
                                ;*********************************;
                                ;      DUNO HOW WE GOT HERE       ;
                                ;*********************************;
ERROR_  SLEEP                   ;
        END                     ;The End