Example: Generating an audio beep using a loudspeaker

//
// Example: Generating an audio beep using a loudspeaker
// This program generates a 500 ms beep once every 2 seconds 
// Written by Ted Burke - 24-Mar-2021
//

#define SPKR 3

void setup()
{
  pinMode(SPKR, OUTPUT);  // make speaker pin a digital output
}

void loop()
{
  analogWrite(SPKR, 127); // sound on
  delay(500);             // 500 ms delay
  analogWrite(SPKR, 0);   // sound off
  delay(1500);            // 1500 ms delay
}