snippet.asm

SetupInt:

  sei      ; Bit 7 - I: Global Interrupt Enable,    wird beim eintritt in die interruptroutine gecleart und RETI wieder gesetzt

  sbx TIMSK, OCIE1A ; Bit 4 - OCE1A: Timer/Counter1 Output CompareA Match Interrupt Enable

  ldi XH, 0x07    ; initialize compare value : 2000   2.048 MHz / 1024 /2000 = 1 Hz ! ----------- 2000 oder 1999 ?!?!

    ldi XL, 0xD0

    out OCR1AL, XH    ; Timer/Counter1 - Output Compare Register A Low Byte

    out OCR1AH, XL    ; Timer/Counter1 - Output Compare Register A High Byte

            ; initialize prescaler

              ; Timer/Counter1 Control Register B - TCCR1B   1 0 1 -> CK / 1024

    sbx TCCR1B, CS12  ; bit 2

    cbx TCCR1B, CS11  ; bit 1

    sbx TCCR1B, CS10  ; bit 0

    sbx TCCR1B, CTC1  ; Bit 3 - CTC1: Clear Timer/Counter1 on Compare Match

    clr XL

    out TCNT1H, XL    ; clear

    out TCNT1L, XL    ; clear

  ret