;
; ***************************************************************************
; ***  Bubble Software Parallax to PIC Source Converter. Copyright 1999.  ***
; ***  http://www.picnpoke.com                 email: sales@picnpoke.com  ***
; ***************************************************************************
;
; PAUSE time
; A general-purpose delay routine that puts the PIC into a do-nothing
; loop for a 16-bit number of milliseconds (1 to 65535) at 4 MHz. Requires
; 16 cycles of overhead for call, return and other processing.

	P = pic16c55
	#include <16c55.inc>   ; processor assembler definitions
	_CONFIG _xt_osc & _wdt_off & _protect_off
 reset start

 org 8
hiB Res d'1' ; MSB of time.
lowB Res d'1' ; LSB of time.
temp Res d'1' ; temporary counter for Pause

; Device data and reset vector
 org 0

start        MOVLW d'0'                 ; Output through RB.
             TRIS 6h
             MOVLW d'3'                 ; Length of delay =
             MOVWF hiB
             MOVLW 0x00E8               ; 3E8h (1000 ms @ 4MHz).
             MOVWF lowB
             MOVLW d'255'               ; Toggle LED(s).
             XORWF 6h
             CALL Pause                 ; Wait 1 second.
             GOTO start                 ; Do it again.

; Upon entry, variables hiB and lowB hold the MSB and LSB of the
; number of milliseconds (1 to 65535) to delay.

Pause        COMF hiB                   ; Take twos complement
             COMF lowB                  ; of the 16-bit counter
             INCF lowB                  
             BTFSC status,z             ; If zero, lowB overflowed,
             INCF hiB                   ; so carry into hiB.
Pause_load   MOVLW d'248'               ; Set up for 1-ms loop.
             MOVWF temp
Pause_loop   NOP                        ; Do nothing.
             DECFSZ temp                ; Do more nothing.
             GOTO Pause_loop
             GOTO $+1                   ; 2-cycle "nop"
             INCF lowB                  ; lowB = lowB+1.
             BTFSC status,z             ; Overflow in lowB?
             INCFSZ hiB                 ; Yes: hiB=hiB+1, overflow?.
             GOTO Pause_load            ; No overflow: do it all again.
             RETLW 0h                   ; Overflow. Return to caller.
             
             
             end