special-issue-x/basics/simple-osc-explained/simple-osc-explained.ino

/*
 * 
 * Simple (PWM) Oscillator Explained
 * 
  Instead of using the Tone() function, you can create a square wave oscillator by 
  turning the digital pin 11 (speakerpin) on (HIGH) and off (LOW) very fast:
  

        |
   HIGH |       ___      ___
        |      |   |    |   |     50% duty cycle
   LOW  |  ____|   |____|   |     (50% on, 50 off) Determined by delayMicroseconds()
        |
        |____________________
                TIME

 * 
 * 
 * 
 * 
 * 
 */

 
#define SPEAKER_PIN 11 

void setup() {
  // set pin 11 as output
  pinMode(SPEAKER_PIN, OUTPUT);
}

void loop() {


    digitalWrite( SPEAKER_PIN, LOW );
    delayMicroseconds( analogRead(A2)*2 ); // wait 
    digitalWrite( SPEAKER_PIN, HIGH );
    delayMicroseconds( analogRead(A2)*2 ); // wait 

  

  //note: delayMircoseconds wont pause your whole code like normal delay() would do
  //so, the code inside the while loop is executed simultaniously with the code in the
  //main loop. See usage in simple-poly-osc.ino
}