LIST        P=16F628A, r=dec, w=-302
        include     "P16F628A.INC"  ; Include header file
        __CONFIG    _LVP_OFF & _BOREN_OFF & _MCLRE_OFF & _PWRTE_ON & _WDT_OFF & _INTRC_OSC_NOCLKOUT
;------------------------------------------------------------
        cblock      0x20    ; Beginn General Purpose-Register
;-------------------------- counters
;place this at very top of codw

                COUNT
                count1
                count2
                count3
                INTCOUNT
;--------------------------
        endc
;--------------------------

        cblock      0x70
                W_TEMP
                STATUS_TEMP
                PCLATH_TEMP
        endc


#DEFINE     pwmu        PORTB,3
;--- Reset --------------------------------------------------
        org     h'00'
        goto        init        ; reset -> init
;--- Interrupt ----------------------------------------------
        org     h'04'
;--------------------------
        movwf       W_TEMP
        swapf       STATUS,W
        banksel     0
        movwf       STATUS_TEMP
        movfw       PCLATH
        movwf       PCLATH_TEMP

        decfsz      INTCOUNT,F
        goto        $+5

        movlw       1
        xorwf       PORTA,F
        movlw       5
        movwf       INTCOUNT
        clrf        TMR0
        bcf     INTCON,T0IF

ISREx       movfw       PCLATH_TEMP
        movwf       PCLATH
        swapf       STATUS_TEMP,W
        movwf       STATUS
        swapf       W_TEMP,F
        swapf       W_TEMP,W
        retfie

init

            CLRF        PORTA                   ; Initialise PORT A by setting ouput data latches
            CLRF        PORTB                   ; Initialise PORT B by setting ouput data latches
        movlw       5
        movwf       INTCOUNT
            MOVLW       H'07'                   ; Turn Comparators off and enable pins for I/O functions
            MOVWF       CMCON                   ;
            BCF         STATUS, RP1             ; Bank 1
            BSF         STATUS, RP0             ; Bank 1
            MOVLW       B'11111110'             ; RA<7:6>, Inputs. RA<5:2> Outputs. RA<1:0> Inputs.
            MOVWF       TRISA                   ;

            MOVLW       B'00000000'             ; RB<7:4> Inputs. RB<3:2> Ouputs.  RB<0:1> Inputs.
            MOVWF       TRISB                   ;
        movlw       0xD7            ;timer 0 1:256 prescale, tmr0 clock source = Tcy
        movwf       OPTION_REG

            BCF         STATUS, RP1             ; Bank 0
            BCF         STATUS, RP0             ; Bank 0
        clrf        TMR0
        bcf     INTCON,T0IF
        bsf     INTCON,T0IE
        bsf     INTCON,GIE
        call        pause           ; wait 126ms
        call        set_timer

;--------------------------

Reset       movlw       99          ;set increment counter
        movwf       COUNT
        movlw       1           ;set CCPR1L to 1
        movwf       CCPR1L
        call        pause           ;wait 126mS
        incf        CCPR1L,F        ;increment CCPR1L
        decfsz      COUNT,F         ;do 99 times
        goto        $-3
        call        pause           ;wait 126mS
        decfsz      CCPR1L,F        ;decrement CCPR1L
        goto        $-2         ;do 99 times
        goto        Reset           ;start over





;~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
set_timer
        clrf        T2CON
        clrf        TMR2
        bsf     STATUS,RP0
        movlw       0xFF
        movwf       PR2     ; compare with 255
        bcf     STATUS,RP0
        movlw       0x02
        movwf       CCPR1L
        movlw       0x03
        movwf       T2CON    ; prescaler 1:16 and postscaler 1:1
        movlw       0x3C
        movwf       CCP1CON
        bsf     T2CON,TMR2ON    ;turn on timer, see pic16f628 datasheet
        return

;************************************************************************
;     Delay                                                              *
;************************************************************************
pause       movlw       0x01     ;126 ms
        movwf       count3
d3      movlw       0x0F    ;63 ms
        movwf       count1
d1      movlw       0xFA    ; 1ms
        movwf       count2
d2      nop
        decfsz      count2,F
        goto        d2
        decfsz      count1,F
        goto        d1
        decfsz      count3,F
        goto        d3
        retlw       0x00
;============================================================
usi     bsf     STATUS,RP0  ; Bank 1
        movlw       0xFF ; all input
        movwf       TRISA
        movlw       0x00
        movwf       TRISB ; all output
        bcf     STATUS,RP0  ; Bank 0
        return
;============================================================
    end
;============================================================