list	P=PIC16F88
	#include <P16F88.INC>
	__CONFIG	_CONFIG1, _INTRC_IO & _WDT_OFF & _PWRTE_ON &_LVP_OFF & _MCLR_OFF & _CCP1_RB3
	__CONFIG    _CONFIG2, _IESO_OFF & _FCMEN_OFF
;***** VARIABLE DEFINITIONS
w_temp		EQU	0x0C        ; variable used for context saving 
status_temp	EQU	0x0D        ; variable used for context saving
tmp			EQU	0x0F
CNT0		EQU	0x20
CNT1		EQU	0x21
CNT2		EQU	0x22
CNT3		EQU	0x23
CNT4		EQU	0x24
w_temp0		EQU	0x25
w_temp1		EQU	0x26
w_temp2		EQU	0x27
w_temp3		EQU	0x28
w_temp4		EQU	0x29


;**********************************************************************
;RESET_VECTOR	CODE	0x000		; processor reset vector
		org 0x000
  		goto    Init              ; go to beginning of program
		org	0x008
		return

Init:
;***** PORT mode set *****
;RA0:3	binary out
;RB3	buzzer
;AN0:4  disable

	BCF	INTCON,GIE	;Interrupt Disable
	BSF		STATUS,RP0	;Set page 1
	CLRF	TRISA
	CLRF	TRISB
	CLRF	ANSEL	; Analog input disable
	MOVLW	0x70	; set INTOSC to 8Mhz
	MOVWF	OSCCON
	MOVLW	0x7D
	MOVWF	PR2		; period 1 msec
	BCF	STATUS,RP0	;Set page 0
	MOVLW	0xff
	MOVWF	PORTA
	MOVWF	PORTB

	MOVLW	0x3e
	MOVWF	CCPR1L	; Duty cycle 50%


	MOVLW	0x06
	MOVWF	T2CON	; TMR2 on, pre scaler 16

Main:
	BCF		PORTA,0
	CALL	Buzzer
	BSF		PORTA,0
	CALL	Sleep1s
	GOTO	Main

;***** Buzzer routines *****
; Buzzer connected to PortB:3
; 1kHz, 20 msec
Buzzer:
	MOVWF	w_temp4
	MOVLW	D'20'
	MOVWF	CNT4
	MOVLW	0x0c
	MOVWF	CCP1CON	; CCP1 enable
	CALL	Sleep1ms
	DECFSZ	CNT4, F
	GOTO	$-2
	CLRF	CCP1CON	; CCP1 disable
	BSF		PORTB,3
	MOVF	w_temp4,W
	RETURN

;***** sleep routines *****
Sleep1s:
	MOVWF	w_temp0
	MOVLW	D'10'
	MOVWF	CNT0
	CALL	Sleep100ms
	DECFSZ	CNT0, F
	GOTO	$-2
	CALL	Sleep1ms
	CALL	Sleep1ms
	CALL	Sleep1ms
	MOVF	w_temp0,W
	RETURN

Sleep100ms:
	MOVWF	w_temp1
	MOVLW	D'97'
	MOVWF	CNT1
	CALL	Sleep1ms
	DECFSZ	CNT1, F
	GOTO	$-2
	MOVF	w_temp1,W
	RETURN

Sleep1ms:
	MOVWF	w_temp2
	MOVLW 	D'256'
	MOVWF	CNT2
Loop2:	NOP
	NOP
	NOP
	NOP
	NOP
	DECFSZ	CNT2, F
	GOTO	Loop2
	MOVF	w_temp2,W
	RETURN

	END                     ; directive 'end of program'