/* Program 2-5 send 440 Hz signal to the buzzer on Arduino
 * This program toggles pin 6 at 440 Hz using 1136 us delay
 * between toggles. Pin 6 is connected to a buzzer on the board.
*/
const int BUZZER = 6;
const int HALF_PERIOD = 1000000 / 440 / 2;

void setup() {                
    /* initialize the digital pin as an output */
    pinMode(BUZZER, OUTPUT);     
}
void loop() {
    for (int i = 0; i < 440; i++) {
        digitalWrite(BUZZER, HIGH);     /* turn the signal to buzzer high */
        delayMicroseconds(HALF_PERIOD); /* wait for half cycle */
        digitalWrite(BUZZER, LOW);      /* turn the signal to buzzer low */
        delayMicroseconds(HALF_PERIOD); /* wait for half cycle */
    }
    delay(1000);
}