hey! wiz family am a new bie in da house please i need immediate help on this sample project i wrote.am having a stacking error when i simulate using proteus please wiz kids in tha house have mercy for an humble learner needs help.you could highlight why and where the problem is and send to ma box o wiz family efizyus@yahoo.com

list p=16f873a ; list directive to define processor
#include <p16f873a.inc> ; processor specific variable definitions

__CONFIG _CP_OFF & _WDT_OFF & _BODEN_OFF & _PWRTE_ON & _RC_OSC & _WRT_OFF & _LVP_ON & _CPD_OFF

; '__CONFIG' directive is used to embed configuration data within .asm file.
; The labels following the directive are located in the respective .inc file.
; See respective data sheet for additional information on configuration word.

;***** VARIABLE DEFINITIONS (examples)

; example of using Shared Uninitialized Data Section
INT_VAR UDATA_SHR 0x71
w_temp RES 1 ; variable used for context saving
status_temp RES 1 ; variable used for context saving
pclath_temp RES 1 ; variable used for context saving


; creating copies of interupt context saving variables in bank1
INT_VAR1 UDATA_SHR 0xF1
w_temp1 RES 1 ; variable used for context saving


; example of using Uninitialized Data Section
TEMP_VAR UDATA_SHR 0x20 ; explicit address specified is not required
temp_count RES 1 ; temporary variable (example)
CBLOCK .14
COUNT
VALUE_L
VALUE_H
ENDC

;**********************************************************************
RESET_VECTOR CODE 0x0000 ; processor reset vector
nop ; nop for icd
pagesel start
goto start ; go to beginning of program


INT_VECTOR CODE 0x0004 ; interrupt vector location

INTERRUPT

movwf w_temp ; save off current W register contents
movf STATUS,w ; move status register into W register
bcf STATUS,RP0 ; select bank0
movwf status_temp ; save off contents of STATUS register
movf PCLATH,w ; move pclath register into w register
movwf pclath_temp ; save off contents of PCLATH register


; isr code can go here or be located as a call subroutine elsewhere

bcf STATUS,RP0 ; select bank0
movf pclath_temp,w ; retrieve copy of PCLATH register
movwf PCLATH ; restore pre-isr PCLATH register contents
movf status_temp,w ; retrieve copy of STATUS register
movwf STATUS ; restore pre-isr STATUS register contents
swapf w_temp,f
swapf w_temp,w ; restore pre-isr W register contents
retfie ; return from interrupt

MAIN_PROG CODE

start
BANKSEL TRISA
CLRF TRISA
MOVLW B'00000011'
MOVWF TRISA
CLRF TRISB
CLRF TRISC



PWM_INIT:
BANKSEL CMCON
BCF CMCON,7 ;SWITCH OFF COMPARATOR
BANKSEL ADCON1
MOVLW 00000110;MAKE PORTA ALL DIGITAL
MOVWF ADCON1
BANKSEL INTCON
BSF INTCON,7
BSF INTCON,6
BANKSEL PR2
MOVLW .249
MOVWF PR2
BANKSEL T2CON
MOVLW B'00000101'
MOVWF T2CON
BANKSEL TRISB
BCF TRISC,2
BANKSEL CCP1CON
CLRF CCP1CON
MOVLW B'00001100'
MOVWF CCP1CON



READ_INPUT:
H_INPUT
BTFSS PORTA,0
GOTO SPEED_H
L_INPUT
BTFSS PORTA,1
GOTO SPEED_L
GOTO READ_INPUT

SPEED_H:
INCF COUNT,1
MOVF COUNT,0
SUBLW .10
BTFSC STATUS,2
GOTO DISPLAY_F
UPDATE_PWM:
MOVF COUNT,0
CALL TABLE
BANKSEL CCPR1L
MOVWF CCPR1L
UPDATE_DISPLAY
MOVF COUNT,0
CALL TABLE_2
MOVWF PORTB
GOTO READ_INPUT

DISPLAY_F:
BTFSS PORTA,1
GOTO L_INPUT
MOVLW B'11100010'
MOVWF PORTB
GOTO DISPLAY_F
SPEED_L:
DECF COUNT,1
MOVF COUNT,0
SUBLW .0
BTFSC STATUS,2
GOTO UPDATE_DOWNDISPLAY
MOVF COUNT,0
UPDATE_PWM4LOWSPEED:
CALL TABLE
BANKSEL CCPR1L
MOVWF CCPR1L
UPDATE_DOWNDISPLAY
MOVF COUNT,0
CALL TABLE_2
MOVWF PORTB
GOTO READ_INPUT
DISPLAY_N:
BTFSC PORTA,1
GOTO H_INPUT
MOVLW B'11011100'
MOVWF PORTB
GOTO DISPLAY_N

TABLE
ADDWF PCL,1
RETLW B'11100010' ;F
RETLW B'11110010' ;1
RETLW B'01001000' ;2
RETLW B'01100000' ;3
RETLW B'00110010' ;4
RETLW B'00100100' ;5
RETLW B'00000100' ;6
RETLW B'11110000' ;7
RETLW B'00000000' ;8
RETLW B'00100000' ;9
TABLE_2
ADDWF PCL,1
RETLW B'00011001' ;0
RETLW B'00110010' ;1
RETLW B'01001011' ;2
RETLW B'01100100' ;3
RETLW B'01111101' ;4
RETLW B'10010110' ;5
RETLW B'10101111' ;6
RETLW B'11001000' ;7
RETLW B'11100001' ;8
RETLW B'11111010' ;9


nop ; code starts here (example)

; remaining code goes here

goto $

END ; directive 'end of program'

 

I'm guessing that you are calling the tables with a value in W greater than 9. Try putting breakpoints at the addwf points and see if W is ever 10 or above.