beep.asm

VCP201_CODE is a FPGA source code.

;****************************************************************************
;FUNCTION: THIS ROUTINE IS TO GENERATE BEEP SOUND.  THE INPUT IS NUMBER OF 
;          OF BEEPS TO BE GENERATED AND IS CONTAINED IN W REGISTER.  THE
;          OUTPUT IS A 4KHZ BEEP SOUND WITH ON AND OFF DURATION OF ABOUT 0.2
;          SECONDS. THE 4KHZ SIGNAL IS GENERATED BY LOOPING THE HIGH AND LOW
;          PULSE IS DONE BY TAKING OUT ONE OF THE 8 BITS OF THE BEEP_CNT WHICH
;          IS A SOFTWARE FREE-RUNNING COUNTER.
;          THE BEEP DURATION IS CONTROLLED BY THE BUFFER TMR_BEEP.
;          
;FILENAME: C:\PROJECTS\SV363\BEEP.ASM
;ROUTINE NAME: P_BEEP
;INPUT: W = NUMBER OF BEEP 
;OUTPUT: NIL
;RAM AFFECTED: 62H
;SUBROUTINE CALL: NIL
;****************************************************************************
p_beep:
	movwf	beep_cnt
beep_lp:
	movlw	DURBZON
	movwf	tmr_beep
beep_on:
	bcf	f_beep
	btfsc	t200us_bit
	bsf	f_beep

	call	p_timer
	movf	tmr_beep,F
	btfss	STATUS,Z
	goto	beep_on

	movlw	DURBZOFF
	movwf	tmr_beep
	bcf	f_beep
beep_off:
	call	p_timer
	movf	tmr_beep,F
	btfss	STATUS,Z
	goto	beep_off

	decfsz	beep_cnt,F
	goto	beep_lp

	return