problem in counting pulse train by using timer0

[asic1984]

timer0 in pic16f877?

hi

i tried to run a code in pic16f977 and simulate it ...but seems that the timer0 is not initialize well ......can u help me in finding the mistake?

     PROCESSOR 16F877
     #INCLUDE "P16F877.INC"


       ORG 0X00
       GOTO START 
       ORG 0X04
       GOTO INT_HANDLER 

       ORG 0X06
START  BSF STATUS,5
       MOVLW 0X00
       MOVWF TRISB
       BCF STATUS,5     ;BANK 0
       MOVLW 0XFF
       MOVWF PORTB      ;PORTB INITIALLY 1`S
       MOVLW 0XA0
       MOVWF INTCON     ;ENABLE TIMER0 AND CLEAR THE FLAG OF THE TIMER 
       movlw 0x00
       movwf OPTION_REG   
           
       

LOOP   GOTO LOOP  


INT_HANDLER MOVLW 0X00
            MOVWF INTCON
            MOVFW PORTA
            XORLW 0XFF
            MOVWF PORTA
            MOVLW 0XA0    ;RENABLE INTERRUPTS
            RETFIE        ;RETURN FROM INTERRUPT  

            END

thanks

 

[olemp]

Re: timer0 in pic16f877?

in your code:
portb pull ups are enabled..
in "INT_HANDLER" you have used PORTA but you haven't initialized PORTA
and there is no instruction like
MOVFW PORTA
(perhaps it may be equal to movf porta????)

 

[asic1984]

Re: timer0 in pic16f877?

hi

will about movfw the mplab didnot say anything error about it but i changed it any way

the mistake was in addressing as the option_reg is in bank1 not 0

about porta sorry for it i write this code in the first for porta and when the timer didnot work i changed to portb

here is the code after the modifications:

     PROCESSOR 16F877
     #INCLUDE "P16F877.INC"


       ORG 0X00
       GOTO START 
       ORG 0X04
       GOTO INT_HANDLER 

       ORG 0X06
START  BSF STATUS,5
       MOVLW 0X00
       MOVWF TRISB
       movlw 0x80          
       movwf OPTION_REG 
       BCF STATUS,5     ;BANK 0
       MOVLW 0XFF
       MOVWF PORTB      ;PORTB INITIALLY 1`S
       movLW 0x00
       MOVWF TMR0
       MOVLW 0XA0
       MOVWF INTCON     ;ENABLE TIMER0 AND CLEAR THE FLAG OF THE TIMER 
         
                
       

LOOP   GOTO LOOP  


INT_HANDLER bcf INTCON,2
            MOVF PORTB,W
            XORLW 0XFF
            MOVWF PORTB
            
            RETFIE        ;RETURN FROM INTERRUPT  

            END

thanks too mcuh for your help