Robots - Notes - IR Remote Control

prog04.asm

;**********************************************************************
; Notes: Toggle Pin 4 on Timer1 overflow vis ISR *
; Toggle Pin 5 in main loop *
;**********************************************************************

list p=12F683 ; list directive to define processor
#include <p12F683.inc> ; processor specific variable definitions

errorlevel -302 ; suppress message 302 from list file

__CONFIG _FCMEN_ON & _IESO_OFF & _CP_OFF & _CPD_OFF & _BOD_OFF & _MCLRE_OFF & _WDT_OFF & _PWRTE_ON & _INTRC_OSC_NOCLKOUT

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




;***** VARIABLE DEFINITIONS
w_temp EQU 0x70 ; variable used for context saving
status_temp EQU 0x71 ; variable used for context saving
counter EQU 0x20





;**********************************************************************
ORG 0x000 ; processor reset vector
goto main ; go to beginning of program


ORG 0x004 ; interrupt vector location
movwf w_temp ; save off current W register contents
movf STATUS,w ; move status register into W register
movwf status_temp ; save off contents of STATUS register


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

bcf STATUS, RP0 ; bank 0
btfsc PIR1, TMR1IF ; Timer1 overflow interrupt?
goto t1_int ; yes goto t1_int
goto end_isr

t1_int ; Routine when Timer1 overflows

btfsc GPIO, 4 ; test GP4 skip next if 0
goto clearbit4 ; else goto clearbit
bsf GPIO, 4 ; set GP4 to 1
goto endtoggle ; goto loop

clearbit4

bcf GPIO, 4 ; set GP4 to 0

endtoggle

bcf PIR1, TMR1IF ; clear the timer1 overflow interrupt flag
goto end_isr ; ready to leave ISR (for this request)

end_isr

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

; remaining code goes here

; initialize timer1
clrf T1CON ; stop Timer1, Internal Clock Source,
; T1 oscillator disabled, prescaler 1:1
clrf TMR1H ; set timer 1 high byte = 0
clrf TMR1L ; set timer 1 low byte = 0
bcf PIR1, TMR1IF ; clear timer1 overflow interrupt flag
bsf STATUS,RP0 ; bank 1
bsf PIE1, TMR1IE ; enable timer1 overflow interrupt
bcf STATUS,RP0 ; bank 0
bsf INTCON, PEIE ; enable peripherals interrupts
bsf INTCON, GIE ; enable global interrupts
bsf T1CON, TMR1ON ; timer1 on

; initialize Pin 5 and 4 as output
; pin 5 toggles by main loop
; pin 4 toggles by timer1 overflow ISR only

bcf STATUS,RP0 ; bank 0
clrf GPIO ; init GPIO
movlw 07h ; set GP<2:0> to
movwf CMCON0 ; digital I/O
bsf STATUS,RP0 ; bank 1
clrf ANSEL ; digital I/O
movlw 0Ch ; set GP<3:2> as input
movwf TRISIO ; set GP<5:4,1:0> as output
bcf STATUS,RP0 ; bank 0

loop
incfsz counter, f ; increment counter and skip next if 0
goto loop ; else goto loop

btfsc GPIO, 5 ; test GP5skip next if 0
goto clearbit ; else goto clearbit
bsf GPIO, 5 ; set GP5 to 1
goto loop ; goto loop

clearbit

bcf GPIO, 5 ; set GP5 to 0
goto loop ; goto loop


; initialize eeprom locations

ORG 0x2100
DE 0x00, 0x01, 0x02, 0x03


END ; directive 'end of program'

 

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