Fading LED
Demonstrates how to set the PWM mode of the Timer/Counter1, a LED @ the PWM output at PORTB.3 fades in and out.
Demonstrates how to set the PWM mode of the Timer/Counter1, a LED @ the PWM output at PORTB.3 fades in and out.
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| ;***** PWM demonstration with LED **** ; this program demonstrates how to set the PWM mde of the Timer/Counter1 ; Target : AT2313 ; Hardware : LED at PORTB3 ;************************************* .include "2313def.inc" .def Temp =r16 ; Temporary register .def pw =r19 ;***** Initialization INIT_SP: ldi temp,RAMEND out spl,temp INIT_PORTB: ser Temp out DDRB,Temp ; Set PORTB to output clr temp out PORTB,temp ; Set PORTB to 0 INIT_TIMER: ldi temp,0 ; Set Output Comp Reg H to 0 out OCR1AH,temp ldi temp,0 ; Set pulse width out OCR1AL,temp ldi temp, 0b10000001 ; Set Timer/Counter1 as an 8-bit PWM out TCCR1A, temp ; ldi temp, 0b00001001 ; Start Timer/Counter1 , set PWM mode to clear OC1(PB3) at upcounting out TCCR1B, temp LOOP: UP: out OCR1AL,pw ; Output to CompareRegister1 which will set the puls width inc pw ; Increase the pulse width rcall delay ; Delay of 0.01s cpi pw,0xFF ; Check if pulse width is max brne UP ; DOWN: out OCR1AL,pw dec pw rcall delay cpi pw,0x00 brne DOWN rjmp LOOP DELAY: ; delay of 0.01s @ 4Mhz ; ============================= ; delay loop generator ldi R17, $43 WGLOOP0: ldi R18, $C6 WGLOOP1: dec R18 brne WGLOOP1 dec R17 brne WGLOOP0 ; ----------------------------- ; delaying 1 cycle: nop ; ============================= ret |