Proteus PIC simulation

[colin mac]

Just started learning asm for PIC16F876A and I can't read an input in Isis with
btfsc or btfss instructions.

STATUS equ 03h
TRISA equ 85h
PORTA equ 05h
COUNT equ 21h
COUNT2 equ 22h

bsf STATUS, 5
movlw b'00001
movwf PORTA
bcf STATUS, 5

start bsf PORTA, 1
call delay
bcf PORTA, 1
call delay
btfss PORTA,0
call stop
goto start

delay decfsz COUNT, 1
goto delay
decfsz COUNT2, 1
goto delay
return

stop goto stop

end

RA1 is flashing an led but I want it to stop when RA0 goes low. It doesn't.
Anyone know what might be wrong?

 

[bananasiong]

Hi,
How's the connection of the schematic? Active low input or active high? To avoid confusion, please use

#include <p16F876A.inc>
bsf STATUS, RP0
movlw b'00001
movwf TRISA
bcf STATUS, RP0

instead of

bsf STATUS, 5
movlw b'00001
movwf PORTA
bcf STATUS, 5

 

[Gayan Soyza]

RA1 is flashing an led but I want it to stop when RA0 goes low. It doesn't.
Anyone know what might be wrong?

Flash	bsf	PORTA,1		;Blink routine
	call	Delay		;//
	bcf	PORTA,1		;//
	call	Delay		;//

Che_SW	btfsc	PORTA,0		;Is Switch pressed?
	goto	Flash		;no,then loop the blink
	
Stop	goto	Stop		;yes,then stop the blink

 

[colin mac]

There wasn't anything wrong with my code? this looks like the same program written in a different way.

STATUS equ 03h
TRISA equ 85h
PORTA equ 05h
COUNT equ 21h
COUNT2 equ 22h

#include <p16F876A.inc>

bsf STATUS, RP0
movlw b'00001
movwf TRISA
bcf STATUS, RP0

Flash	bsf PORTA, 1	
    	call Delay	
	bcf PORTA, 1	
        call Delay		

Che_SW btfsc PORTA,0		
	goto Flash		
	
Stop goto Stop

Delay decfsz COUNT, 1
      goto Delay
      decfsz COUNT2, 1
      goto Delay
      return
end

Anyway, Proteus is acting up on me with that code too. RA1 doesn't toggle when RA0 is both high and low now.

Could you tell me how to select the RC oscillator so I can try it in real life please?

 

[bananasiong]

Hi,
Check the configuration setting from the template provided by Microchip and refer to the inc file.

*EDIT:
Once you have

#include <p16F876A.inc>

you don't need these anymore

STATUS equ 03h
TRISA equ 85h
PORTA equ 05h

because they are predefined in the inc file.

 

[colin mac]

Ok thanks, I looked in your files and found

_RC_OSC EQU H'3FFF'

If I use:

_config _RC_OSC

The RC oscillator is then selected? or do I need to turn the other things on and off?

 

[bananasiong]

Hi,
Other need to be configured too. Check the datasheet under Special Features of the CPU, bit by bit. The code protection for the program memory and EEPROM depends on you whether or not to set them. Usually high voltage programming (bit 7) is used, depends on your programmer. BOR and PWRTEN are good to be enabled. WDT is disabled.
It takes some time to understand, but for the first time, just copy other's example and test.

 

[colin mac]

Hi,
Other need to be configured too. Check the datasheet under Special Features of the CPU, bit by bit. The code protection for the program memory and EEPROM depends on you whether or not to set them. Usually high voltage programming (bit 7) is used, depends on your programmer. BOR and PWRTEN are good to be enabled. WDT is disabled.
It takes some time to understand, but for the first time, just copy other's example and test.

Ok, thanks you. I'll look into it.