|
|
|
Aseemble Language question
|
|
Date: 2008/09/07 12:20
|
By: Roger
|
Status: Visitor
|
|
|
|
|
|
|
Hi,
I am new to PIC programming and have run into a problem with my code.
I want to set a spicific bit on PortB to light up a LED but I want to be able to change which bit I set so I thought I would set up a piece of code as below
MOVLW 1 ;PUT 1 IN W
MOVWF COUNT ; PUT W IN COUNT
MAIN
BSF PORTB,COUNT ;TURN ON LED
CALL DELAY1 ;WAIT 1 SECOND
BCF PORTB,COUNT ;TURN LED OFF
CALL DELAY1 ;WAIT 1 SEC
CALL DELAY1 ;WAIT 1 SECOND
INCF COUNT ;INCREMENT COUNT
GOTO MAIN ;LOOP FOREVER
Now what I expected to happen was for each led to come on and then go off starting with LED1 and moving up one at a time, but what actually happens is that LED0 comes on and then goes off.
The offending line is BSF PORTB,COUNT does anyone know why I cannot do this?
|
|
|
|
|
|
Re:Aseemble Language question
|
|
Date: 2008/09/11 07:45
|
By: DaveS
|
Status: Visitor
|
|
|
|
|
|
|
COUNT is an 8 bit file register and as such cannot be used as a PORTB bit.
Try:-
MOVLW 1 ;PUT 1 IN W
MOVWF COUNT ; PUT W IN COUNT
MAIN
movf;TURN ON LED
CALL DELAY1 ;WAIT 1 SECOND
BCF PORTB,COUNT ;TURN LED OFF
CALL DELAY1 ;WAIT 1 SEC
CALL DELAY1 ;WAIT 1 SECOND
INCF COUNT ;INCREMENT COUNT
GOTO MAIN ;LOOP FOREVER
|
|
|
|
|
|
Re:Aseemble Language question
|
|
Date: 2008/09/11 07:53
|
By: DaveS
|
Status: Visitor
|
|
|
|
|
|
|
Sorry, pressed wrong button. I'll start again.
COUNT is an 8 bit file register and as such cannot be used as a PORTB bit.
Try:-
MOVLW 1 ;PUT 1 IN W
MOVWF COUNT ; PUT W IN COUNT
MAIN
movf COUNT,W;put contents of count in W
movwf PORTB ; W to PORTB
CALL DELAY1 ;WAIT 1 SECOND
clrf PORTB;TURN LED OFF
CALL DELAY1 ;WAIT 1 SEC
CALL DELAY1 ;WAIT 1 SECOND
INCF COUNT ;INCREMENT COUNT
GOTO MAIN ;LOOP FOREVER
This will cause the leds to count up in binary however. To achieve what you want replace incf COUNT with RLF COUNT, F
|
|
|
|
