;*******************************************************************************
;                                                                              *
;    Filename:     Laser_Pantograph.asm                                        *
;    Date:         8/5/2014                                                    *
;    File Version: 1.0                                                         *
;    Author:       The Lightning Stalker                                       *
;    Company:      Lightning Industries                                        *
;    Description:  Implements countdown timer and remote switch for            *
;                    facilitation of compliance with FDA regs.                 *
;                                                                              *
;*******************************************************************************
;                                                                              *
;    Revision History:                                                         *
;                                                                              *
;*******************************************************************************

#define SWITCH      GPIO,GP3        ; Remote switch
#define COMP        GPIO,GP2        ; Comparator output
#define PS_ON       shadow,GP0      ; ATX PS_ON
#define PS_ON_MASK  b'00000001'     ; Bitmask for PS_ON (GP2)
#define BEEP        shadow,GP1      ; Have a buzzer for some output.
#define BEEP_MASK   b'00000010'     ; Bitmask to toggle the buzzer
#define DoIBeep     Beep,0          ; boolean beeping toggle

;*******************************************************************************
; Processor Inclusion
;*******************************************************************************

#include "p10f200.inc"
#include "Debounce.inc"

; CONFIG
; __config 0xFFEB
 __CONFIG _WDTE_OFF & _CP_OFF & _MCLRE_OFF

;*******************************************************************************
; Variable Definitions
;*******************************************************************************

GPR_VAR         UDATA
TimerL          RES 1
TimerH          RES 1
TimerE          RES 1
TimerW          RES 1
Beep            RES 1
shadow          RES 1

;*******************************************************************************
; Reset Vector
;*******************************************************************************

RES_VECT  CODE    0x0000            ; processor reset vector
    GOTO    START                   ; go to beginning of program

;*******************************************************************************
; MAIN PROGRAM
;*******************************************************************************

MAIN_PROG CODE                      ; let linker place main program

START

Reset
    movwf   OSCCAL                  ; load oscillator calibration value
    bcf     OSCCAL,FOSC4            ; disable FOSC/4 output on pin 3
    movlw   b'10011111'             ; put Timer0 in timer mode, set pin 3 as GP2
    option                          ; and enable weak pull-ups


Init
    movlw   PS_ON_MASK              ; Clear all output (latch)
    movwf   GPIO                    ; except for GP0, which is inverted PS_ON
    movwf   shadow                  ; and output register shadow
    movlw   0xff                    ; Set GP2 & 3 as input, GP0 & 1 as output
    xorlw   PS_ON_MASK
    xorlw   BEEP_MASK
    tris    GPIO                    ; Load TRIS

;goto Main ;***************REMOVE*********REMOVE**********REMOVE!!!!!
;Sound alarm, light LED, and begin 25 second countdown.
    movlw   BEEP_MASK
    xorlw   PS_ON_MASK              ; remember, PS_ON HAS TO stay high!
    movwf   shadow
    movwf   GPIO
    movlw   .6                      ; Sound alarm for one second
    movwf   TimerE
    movlw   .19
    movwf   TimerH
    movlw   .173
    movwf   TimerL
Delay1s
    decfsz  TimerL,f
    goto    Delay1s

    decfsz  TimerH,f
    goto    Delay1s

    decfsz  TimerE,f
    goto    Delay1s

    movlw   PS_ON_MASK
    movwf   shadow                  ; Everything off
    movwf   GPIO

    movlw   .122                    ; Delay another 24 seconds
    movwf   TimerE
    movlw   .193
    movwf   TimerH
    movlw   .129
    movwf   TimerL
Delay24s
    decfsz  TimerL,f
    goto    Delay24s

    decfsz  TimerH,f
    goto    Delay24s

    decfsz  TimerE,f
    goto    Delay24s

    goto    $+1


Main
;Wait for remote signal
    btfsc   SWITCH                  ; someone pressing the switch?
    goto    $ + 5                   ; keep going
    call    SwitchDebounce          ; Debounce it then!
    xorlw   1                       ; Did it
    btfss   STATUS,Z                ; bounce?
    goto    SwitchPressed           ; nope.avi

    goto    Main


SwitchPressed
    clrf    shadow                  ; Bring laser online
    clrf    GPIO

LaserON
    btfss   SWITCH                  ; Switch still on?
    goto    LaserON                 ; Yes
    movlw   PS_ON_MASK              ; No
    movwf   shadow                  ; Shut the laser off
    movwf   GPIO
    goto    Main


    END                             ; Directive 'end of program'

Debounce.inc -

;******************************************************************************
;SwitchDebounce - Waits for switch to release and settle
;******************************************************************************
; The SWITCH must be a steady high for 10 milliseconds to be considered
; released and debounced. The debounce routine sets a 10 mSec timer and looks
; for a high SWITCH input. The timer is reset to 10 mSec for every occurance of
; a low SWITCH input.
;
; Debounce timer constants (TenMSH and TenMSL) are a function of the
; instruction execution time and number of instructions in each loop. Debounce
; time for this example is:
; Timer overhead + TenMSH * [outer loop time + (TenMSL * inner loop time)]
; or [2 + TenMSH * (5 + (TenMSL * 5))]*(4/fosc)= .010
;
; Arbitrarily choosing 99 for TenMSL we solve for TenMSH
; 2 + TenMSH * (5 + (99 * 5)) = 10,000
; TenMSH = 9998/500 ~ 20

#define TenMSH 		.20
#define TenMSL		.99


DEBOUNCE_VAR    UDATA
CountH          RES 1   ; debounce counter MS byte
CountL          RES 1   ; debounce counter LS byte


DEBOUNCE CODE
SwitchDebounce

	movlw	TenMSH		; set outer timer loop count
	movwf	CountH		; outer loop overhead is 2 instructions

;========== outer loop [TenMSH * 5 instruction cycles*(Inner loop time)] ======
SDA10
	movlw	TenMSL		; set inner timer loop
	movwf	CountL
;----------------- inner loop (TenMSL * 5 instruction cycles) -----------------
SDA20
	btfsc	SWITCH	; test SWITCH input
	retlw 1         ; SWITCH was high - return nonzero status

	decfsz	CountL,f	; inner loop countdown
	goto	SDA20		; test SWITCH while counting

;-------------------------------- inner loop ----------------------------------

	decfsz	CountH,f	; outer loop countdown
	goto	SDA10		; reset inner loop after each outer loop count

;================================ outer loop ==================================

	retlw 0 		; full countdown and no bounces achieved - exit