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Simple noise on the arduino
2011-10-02 21:04:00 +0200
arduino music sound

Inspired by the minimalists I tried this out on the arduino:


int speakerPin = 11;

void outp(byte value) {
    analogWrite(speakerPin, value); delayMicroseconds(200);
}

void setup() {
    pinMode(speakerPin, OUTPUT);


    // Set up Timer 2 to do pulse width modulation on the speaker
    // pin.

    // Use internal clock (datasheet p.160)
    ASSR &= ~(_BV(EXCLK) | _BV(AS2));

    // Set fast PWM mode  (p.157)
    TCCR2A |= _BV(WGM21) | _BV(WGM20);
    TCCR2B &= ~_BV(WGM22);

    // Do non-inverting PWM on pin OC2A (p.155)
    // On the Arduino this is pin 11.
    TCCR2A = (TCCR2A | _BV(COM2A1)) & ~_BV(COM2A0);
    TCCR2A &= ~(_BV(COM2B1) | _BV(COM2B0));

    // No prescaler (p.158)
    TCCR2B = (TCCR2B & ~(_BV(CS12) | _BV(CS11))) | _BV(CS10);

}

void loop() {
  int t;
  for(t=0;;t++){ outp(t*((t>>12|t>>8)&63&t>>4)); }
}

It does sound somewhat similar. So right now it's just a hack in order to try it out.

Note:
The code above is corrected with a little help from Davey at forsken.