;TJACO'S DESIGN GRAVEYARD: WWW.GEOCITIES.COM/TJACODESIGN		;
;22 JULY 2002								;
;CERBERES : MINI ROBOT WITH IR EYES  					;
;USES PIC16F84 µCONTROLLER						;
;WRITTEN IN MICROCHIP ASSEMBLY USE MPASM ASSEMBLER FROM MPLAB		;
;MPLAB CAN BE DOWNLOADED FROM WWW.MICROCHIP.COM				;

;***SET UP THE CONTANTS & VARIABLES****

       LIST            P=16C84
       ERRORLEVEL      -302    ;SUPPRESS BANK SELECTION MESSAGES

STATUS	EQU H'03'		;STATUS REGISTER
TRISB 	EQU H'86'		;TRISB REGISTER FOR SETUP OF PORTB
PORTB 	EQU H'06'		;PORTB REGISTER TO DRIVE PORT B
COUNT1 	EQU H'0C'		;COUNT VARIABLE 1 IS IN GENERAL PURPOSE REG 08H
COUNT2 	EQU H'0D'		;COUNT VARIABLE 2 IS IN GENERAL PURPOSE REG 09H

;***SET UP PORT B IN & OUTPUT****
	BSF 	STATUS,5	;SWITCH TO BANK0 TO SET UP PORT B
	MOVLW 	B'11110000'	;RB7,6,5,4 IS INPUT
	MOVWF 	TRISB		;RB3,2,1,0 IS OUTPUT
	BCF 	STATUS,5	;SWITCH BACK TO BANK0 TO USE PORT B

;***MAIN PROGRAM****
START	MOVLW 	B'00000101'	;MAKE RB0&2 HIGH: MOVE FORWARD
	MOVWF 	PORTB		;
	MOVLW 	H'FE'		;RESET COUNT1 TO 254
	MOVWF 	COUNT1		;	
	MOVLW 	H'FE'		;RESET COUNT2 TO 254
	MOVWF 	COUNT2		;
	BTFSS 	PORTB,5		;CHECK RB5 (INPUT); IF IT IS LOW
	CALL 	BACKL		;THEN EXECUTE BACKLEFT ROUTINE
	BTFSS 	PORTB,6		;CHECK RB6 (INPUT); IF IT IS LOW
	CALL 	BACKR		;EXECUTE BACKRIGHT ROUTINE
	GOTO 	START		;RETURN TO LABEL START

;***BACKLEFT ROUTINE****
BACKL	MOVLW 	B'00001010'	;MAKE RB1&3 HIGH: MOVE BACKWARD
	MOVWF 	PORTB		;
	CALL 	DELAY		;
	MOVLW 	B'00001001'	;MAKE RB2&3 HIGH: ROTATE LEFT
	MOVWF 	PORTB		;
	CALL 	DELAY		;
	RETURN
;***BACKRIGHT ROUTINE****
BACKR	MOVLW 	B'00001010'	;MAKE RB1&3 HIGH: MOVE BACKWARD
	MOVWF 	PORTB		;
	CALL 	DELAY		;
	MOVLW 	B'00000110'	;MAKE RB2&3 HIGH: ROTATE RIGHT
	MOVWF 	PORTB		;
	CALL 	DELAY		;
	RETURN

DELAY	MOVLW 	H'EE'		;RESET ALL COUNTER VARIABLES
	MOVWF 	COUNT1		
	MOVLW 	H'99'	
	MOVWF 	COUNT2

LOOP1	CLRWDT			;RESET THE WATCHDOG TIMER
	DECFSZ 	COUNT1,1	;this is a delay loop    
	GOTO 	LOOP1		;tuned to make Cerberes 
	DECFSZ	COUNT2,1	;turn about 90 degrees
	GOTO	LOOP1	
	RETURN

	END;