title “Flash_D0.asm – Flash D0 LED”

; ----------------------------------
; Flash_D0.asm  
;
; Microprocessors A 17.383
;
; xxxxxxxx - Put in Semester (i.e. Fall 2010) here
;
; xxxxxxxx - Put in your name here
;
; xx/xx/xx - Put date here  
;
; ----------------------------------

 list r=dec

#include "p16f684.inc"

 __CONFIG _FCMEN_OFF & _IESO_OFF & _BOD_OFF & _CPD_OFF & _CP_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTOSCIO

; ----------------------------------
; Defining constants or variables in data memory space

 Cblock 0x20		   			; start of GPR

count		   	   			; 

 endc			   			; This directive must be 
			   			; supplied to terminate the
			   			; cblock list
;
; ----- main program -------------- 

		org	0x000	   		; Hex address 0x000, the first
			   			; program memory location
;
start		BCF 	STATUS,RP0  		; Select Bank 0
;
		CLRF 	PORTA	   		; Initialize PORTA (to all zeros)
;
		MOVLW 	7	   		; Load w with 7 
		MOVWF 	CMCON0	   		; Load CMCON0 with 7
			   			; Turns off comparators
;
		BSF 	STATUS,RP0 		; Select Bank 1
;
		CLRF 	ANSEL      		; Shut off ADC (digital I/O)
;
		MOVLW	b'001111'  		; Load w – RA4 and RA5 outputs
		MOVWF	TRISA	   		; copy w to TRIS PORTA 
; 
		BCF 	STATUS,RP0 		; Select Bank 0
; 
Loop		BSF 	PORTA,4    		; Make RA4 high -- D0 ON
;
		CALL 	Delay 	   		; Goto the delay routine
;
		BCF 	PORTA,4    		; Make RA4 low -- D0 OFF
;
		CALL 	Delay 	   		; Goto the delay routine
;
		GOTO	Loop	   		; Do it again
;
;
Delay		MOVLW	10	   		; Decimal 10
		MOVWF	count  			; Initialize counter to 10
Repeat		DECFSZ	count,f	   		; Decrement counter
		GOTO	Repeat	   		; If counter <> 0
		RETURN		   		; If counter = 0 (end delay)
;
 end