[PIC] Infra red sensor based control of Stepper motor.

	list		p=16f877
 	include		<p16f877.inc>
	__CONFIG _CP_OFF & _WDT_OFF & _XT_OSC & _LVP_OFF

	c1 equ 0x21;  Timer counter
	c2 equ 0x22;

	ANTI equ 0x23;
	CLCK equ 0x24;

	org   0x00;
    goto  start; // skip over interrupt vector
    org   0x04;
    goto  serviceinterrupts;

start
	call	clearall;
	call	initport;
	call	inittimer;
	call	ini_adc;
	bsf		INTCON, GIE;
	bsf		INTCON, T0IE;

Get_Input
	call 	ADC;
	call	stay_stuck;
	goto 	Get_Input;

ADC
	bsf ADCON0, 0; ADON: A/D On bit. 1 = 0n, 0 = OFF
	bsf ADCON0, 2; GO/DONE: A/D Conversion Status bit. 1 = conversion in progress, 0 = conversion not in progress

	; CHS2:CHS0: Analog Channel Select bits [111 = Channel 7 (AN7)]
	bsf ADCON0, 3; CHS0 = 1
	bsf ADCON0, 4; CHS1 = 1
;	bsf ADCON0, 5; CHS2 = 1

polling 
	btfsc ADCON0,2; Checking for A/D Conversion Status bit. If ADCON0 = 1, loop continues. If ADCON0 = 0, skips "goto polling"
goto polling;
	
	movf ADRESH,0;
	movwf c2;
	return;

clearall
	clrf	c1;
	clrf	c2;
	clrf	ANTI;
	clrf	CLCK;
	return;

initport
	bsf     STATUS, RP0;
	movlw   b'00000000'; Make all pins of port B as output
	movwf   TRISB;
	bcf     STATUS, RP0;
	return;

inittimer
 	clrf    TMR0;
   	bsf     STATUS, RP0;
   	movlw	b'00000011';
	movwf	OPTION_REG;
    bcf     STATUS, RP0;
	return;

ini_adc;
	bsf STATUS,RP0;
	movlw 0x00;
	movwf ADCON1;
	bcf STATUS,RP0;
    return;

serviceinterrupts
	bcf 	INTCON, T0IF;
	movlw	.5;
	movwf	TMR0;
	incf	c1,1;
	retfie;

rotate_antclck	
		   		;dcba
    movlw  b'00000010';  b'00000001';
	movwf  PORTB;
;	call   delay;
	movlw  b'00000001';  b'00000010'
	movwf  PORTB
;	call   delay;
	movlw  b'00001000';   b'00000100'
	movwf  PORTB
;	call   delay;
	movlw  b'00000100';   b'00001000'
	movwf  PORTB
;	call   delay;
	movlw  b'00000010';   b'00001000'
	movwf  PORTB
;	call   delay;

	movlw .1;
	movwf ANTI;

	movlw .0;
	movwf CLCK;

	call Get_Input;
	return;

rotate_clck	
		   	;dcba
	movlw  b'00000100'; b'00001000'
	movwf  PORTB
;	call   delay;
	movlw  b'00001000'; b'00000100'
	movwf  PORTB
;	call   delay;
	movlw  b'00000001'; b'00000010'
	movwf  PORTB
;	call   delay;
	movlw  b'00000010'; b'00000001';
	movwf  PORTB;
;	call   delay;
	movlw  b'00000100'; b'00001000'
	movwf  PORTB
;	call   delay;

	movlw .0;
	movwf ANTI;

	movlw .1;
	movwf CLCK;

	call Get_Input;
	return;

stay_stuck
	call delay;
	call Checking_for_IR;
	goto stay_stuck;

Checking_for_IR
	movlw c2;
	sublw .5; 	//Giving the ON value, if both are same
	btfss STATUS, C;	BTFSS f,b ...testing for IR.If bit ‘b’ in register ‘f’ is ‘0’, the next
									;instruction is executed.If bit ‘b’ is ‘1’, then the next instruction
									;is discarded and a NOP is executed instead.

	call IR_1;			if IR = 1, then C = 0, this line is executed.
	call IR_0;			if IR = 0, then C = 1, this line is executed.			
	return;

IR_1
	movlw ANTI;
	xorlw .0; 
	btfss STATUS, Z;

	call rotate_antclck;	As IR = 1, if Z = 0, this line is executed.
	call delay;				As IR = 1, if Z = 1, this line is executed.
	return;
IR_0
	movlw CLCK;
	xorlw .0; 
	btfss STATUS, Z; if CLCK = 0, then Z = 0
					;if CLCK = 1, then Z = 1
					;BTFSS f,b ...testing for IR.If bit ‘b’ in register ‘f’ is ‘0’, the next
									;instruction is executed.If bit ‘b’ is ‘1’, then the next instruction
									;is discarded and a NOP is executed instead.

	call rotate_clck;	As IR = 0, if Z = 0, this line is executed.
	call delay;			As IR = 0, if Z = 1, this line is executed.
	return;
	

delay		;delay after light off is 2-times(repeat1+repeat2)
	clrf    c1;

repeat		;delay 1sec
	movf	c1,0;
	xorlw	.250; 
	btfss	STATUS,Z;
	goto	repeat;
    return;


    end