Použití časovačů k běhu úloh

Protože pro vážnější práci nemohu mít založený program na čekacích smyčkách, zkoušel jsem dnes rozblikat LED diodu s použitím časovače. Časovač generuje přerušení a obslužná rutina pak počítá tato přerušení a po určitém počtu změní stav LED diody. Tento přístup mi fungoval. Program jsem ale přepracoval a uvádím jeho poslední verzi.

Diodou na PB3 bliká starý kód s použitím čekacích smyček.
Kód s použitím časovače blikal diodou na PB4 ale je neaktivní.
Na PB4 jsem připojil sluchátko a s pomocí druhého časovače generuji zvuk.

;; Tabulka vektorů přerušení
       .ORG 0
RESET:  RJMP    MAIN            ; Reset Handle
V_INT0: RJMP    RESET           ; External IRQ0 handler
V_IOPCH:RJMP    RESET           ; Pin Change Interrupt
       RJMP    T1CMA           ; Timer1 Compare Match A
V_T1OVF:RJMP    RESET           ; Timer1 Overflow
V_T0OVF:RJMP    T0OVF           ; Timer/Counter0 Overflow
V_EERDY:RJMP    RESET           ; EEPROM Ready
V_ANAC: RJMP    RESET           ; Analog Comparator
V_ADCCC:RJMP    RESET           ; ADC Conversion Complete
       .ORG 9

;;; Initialize the MCU
INIT:
       ;;; Initialize T0 as interrupt source delivering ticks.
       ;LDI W,CS0CK1024                ; 1562.5Hz (6.1Hz)
       ;LDI W,CS0CK256         ; 6250.0 Hz (24.4Hz)
       LDI W,CS0CK64           ; 25kHz (97.66Hz)
       ;LDI W,CS0CK8           ; 200kHz (782.25Hz)
       OUT TCCR0,W

       ;;; Initialize T1 as the source for the beep frequency.
       ;; Set CTC1 to Reset Counter to $00 on Compare Match A
       ;; Set COM1A to Timer/Counter disconnected from output pin OC1A
       ;; Set source to CK (cca 1.6MHz)
       ;; Set Prescaler to CK/1024 (cca 1562.5Hz, 0.64ms)
       ; LDI W,(CTC1 | CS1CK1024)
       ; LDI W,(CTC1 | CS1CK512)       ; 3125Hz
       ; LDI W,(CTC1 | CS1CK256)       ; 6250Hz
       LDI W,(CTC1 | CS1CK128) ; 12500Hz
       OUT TCCR1,W
       ;; Set the divide factor, the compared value.
       LDI W,3                 ; 12500Hz/3 = 4166.6 Hz
       OUT OCR1A,W


       ;; Reset all counters and prescalers.
       LDI W,0
       OUT TCNT0,W
       OUT TCNT1,W
       LDI W,(FOC1A | PSR1 | PSR0)
       OUT SFIOR,W

       ;; Clear Interrupt Flags for all counters.
       LDI W,(OCF1A | TOV1 | TOV0)
       OUT TIFR,W

       ;; Allow Interrupt from Counter 1 Compare Match and Counter 0 Overflow
       LDI W,(OCIE1A | TOIE0)
       OUT TIMSK,W

       RET


;;; Main code executed after power on and/or reset.
MAIN:

       ; We don't initialize stack (SPL,SPH) because ATtiny15
       ; contains hardware stack 3 level deep.

       ;; Initialize
       LDI W,$18               ; PB3,PB4 out, only
       OUT DDRB,W

       RCALL INIT
       SEI
       ;; All peripherals are initialized, now the main program.


       ;; Before main loop and flashing led we do a reset blinking.
       LDI RA,16
RSTFL:
       RCALL BLINK_RB3
       LDI R22,1
       RCALL DLY100MS
       DEC RA
       BRNE RSTFL

       SBI PORTB,3             ; LED on
       LDI R22,6
       RCALL DLY3
       CBI PORTB,3             ; LED off
       RCALL DLY100MS

       CBI PORTB,3
;;; Main Program Loop, the old code running in prallel.
LOOP:
       RCALL BLINK_RB3

       LDI R22,1
       RCALL DLY3

       ; SBI PORTB,4
       LDI R22,2
       RCALL DLY3

       RCALL BLINK_RB3
       ; CBI PORTB,4
       RCALL DLY
       RCALL DLY
       RCALL DLY
       RCALL DLY
       RCALL DLY

       RJMP LOOP

       ;; Zpožďovací procedura

DLY:
       LDI R22,2
DLY3:   LDI R21,255
DLY2:   LDI R20,255
DLY1:   DEC R20
       BRNE DLY1
       DEC R21
       BRNE DLY2
       DEC R22
       BRNE DLY3
       RET
;;; Timer0 is used in creation of tick for software.  This interupt
;;; should be generate with 25kHz frequency.
T0OVF:
       ;; Because owerflow, we need to set the value.
       LDI WI,7        ; With CK8 this should generate 100Hz overflow
       OUT TCNT0,WI

       ;; Now we generate slower signal
       DEC T0L
       BRNE NOSLOW
       ;; Counter is zero.  Initialize for next cycle and generate SLOW TICK
       LDI T0L,100-1
       ;; SLOW TICK
       ; The RB4 is for earphone.
       ;RCALL BLINK_RB4
NOSLOW:
       RETI
;;; Blink the LED on RB4 pin.  We do this by inverting the value on the pin.
BLINK_RB4:
       ;; Read the RB4 and negate it to genereate tone.
       SBIC PORTB,4
       RJMP RB4CLR
RB4SET: SBI PORTB,4
       RJMP RB4Done0
RB4CLR: CBI PORTB,4
RB4Done0:
       RET

;;; Blink the LED on RB3 pin.  We do this by inverting the value on the pin.
BLINK_RB3:
       ;; Read the RB3 and negate it to genereate tone.
       SBIC PORTB,3
       RJMP RB3CLR
RB3SET: SBI PORTB,3
       SBR BITF,0b00000001     ; Enable beep
       RJMP RB3Done0
RB3CLR: CBI PORTB,3
       CBR BITF,0b00000001     ; Stop beep
RB3Done0:
       RET

;;; Timer/Counter 1 Compare Match A Interrupt Routine.  This generate tone.
;;; Because this interrupt is caled often it should be as short as possible.
T1CMA:
       SBRC BITF,0
       RCALL BLINK_RB4
       RETI