title: Arduino PWM fading led with avra
body: <p>I'm writing Arduino UNO (=ATMega328P-PU) programs in assembly to save memory, so I use avra.exe (same as atmel studio's avrasm32) to compile and avrdude to upload, and simple programs like blinking run fine. But now i tried to half-bright a LED with pwm. I checked up my code for errors but I didn't find any, but the LED just full brighs. I checked wiring too. Here's my pwm.asm code:</p>
  
  <pre><code>.nolist
  .include "m328pdef.inc"
  .list
  
  .cseg
  .org 0x00
       rjmp start
  .org 0x34
   start: sbi ddrb, 5 ;pin 13
          sbi portb, 5 ;pin 13 on, just to compare with the PWMed led
          sbi ddrd, 5 ;pin 5 pwm
          ldi r16, 0b00100011 ;fast pwm mode, non inverted pwm at oc0b = pin 5
          out tccr0a, r16 ;I'm using Timer0
          ldi r16, 0b00000001 ;no prescaler
          out tccr0b, r16
          ldi r16, 128 ; duty cycle = 50%
          out ocr0b, r16
  
    loop: rjmp loop
  </code></pre>
  
  <p>I tried to change duty cycle value but nothing changes.</p>