radix dec
spkr equ 1 ; spkr on RB0
;--< variables >---------------------------------------------------
delayhi equ 0x20 ; DelayCy() subsystem
beepctr equ 0x21 ; beep subroutine
;--< macros >------------------------------------------------------
clock equ 4 ; 4, 8, 12, 16, 20 (MHz), etc.
usecs equ clock/4 ; cycles/microsecond multiplier
msecs equ clock/4*1000 ; cycles/millisecond multiplier
DelayCy macro delay ; 11..327690 cycle range
movlw high((delay-11)/5)+1
movwf delayhi
movlw low ((delay-11)/5)
call uDelay-((delay-11)%5)
endm
;******************************************************************
; Main program *
;******************************************************************
org 0x000
v_reset
call beep ; beep |B0
DelayCy(100*msecs) ; delay 1/10th second |B0
goto v_reset ; loop forever |B0
;******************************************************************
; beep (32-msec 500-Hz) *
;******************************************************************
beep
movlw 32 ; |B0
movwf beepctr ; beepctr = 32 |B0
loop
movf PORTB,W ; |B0
xorlw 1<<spkr ; |B0
movwf PORTB ; toggle speaker pin
DelayCy(1*msecs-6) ; delay 1-msec minus 6 cycles |B0
decfsz beepctr,F ; done? yes, skip, else |B0
goto loop ; |B0
return ; |B0
;******************************************************************
; K8LH DelayCy() subsystem 16-bit uDelay(11..327690 cycle) sub' *
;******************************************************************
nop ; entry for (delay-11)%5 == 4 |B0
nop ; entry for (delay-11)%5 == 3 |B0
nop ; entry for (delay-11)%5 == 2 |B0
nop ; entry for (delay-11)%5 == 1 |B0
uDelay addlw -1 ; subtract 5 cycle loop time |B0
skpc ; borrow? no, skip, else |B0
decfsz delayhi,F ; done? yes, skip, else |B0
goto uDelay ; do another loop |B0
return ; |B0
;******************************************************************
end