Project 5 - Distance detector

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Fritzing image

Resistor 100ohm
Sensor Ping Parallax
Buzzer
Led

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Arduino code

/* 
2 sept 2011 - Massimo Pacilio
Distance detector.

Sensor: Ground, DigitalPin 7, 5V
Buzzer: Ground, DigitalPin 8
Led:    Ground, DigitalPin 13

This code is in public domain
*/

const unsigned int BUZZER_PIN = 8;
const unsigned int PING_SENSOR_IO_PIN = 7;
const unsigned int LED_PIN = 13;

void setup() {
  pinMode(LED_PIN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
}

void loop() {
  pinMode(PING_SENSOR_IO_PIN, OUTPUT);
  digitalWrite(PING_SENSOR_IO_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(PING_SENSOR_IO_PIN, HIGH);
  delayMicroseconds(5);
  digitalWrite(PING_SENSOR_IO_PIN, LOW);
  pinMode(PING_SENSOR_IO_PIN, INPUT);
  const unsigned long duration = pulseIn(PING_SENSOR_IO_PIN, HIGH);
  const unsigned threshold = (microseconds_to_cm(duration));
  
  if (duration == 0) {
    digitalWrite(LED_PIN, LOW);
  } 
  else if (threshold <= 35 && threshold >= 21) {
    blink1();
    sonar1();    
    }
  else if (threshold <= 20 && threshold >=6) {
    blink2();
    sonar2();
    }
  else if (threshold <=5) {
    digitalWrite(LED_PIN, HIGH);
    sonar3();
    }
  else {
    digitalWrite(LED_PIN, LOW);
    }
  
  delay(100);
}

unsigned long microseconds_to_cm(const unsigned long microseconds) {
  return microseconds / 29 / 2;
}

void blink1() {
    digitalWrite(LED_PIN, HIGH);
    delay(200);
    digitalWrite(LED_PIN, LOW);
    delay(200);
}
void blink2() {
    digitalWrite(LED_PIN, HIGH);
    delay(50);
    digitalWrite(LED_PIN, LOW);
    delay(50);
}
void sonar1() {
  // play a note on pin 8 for 200 ms:
  tone(8, 1047, 200);
  delay(400);
}
void sonar2() {
  // play a note on pin 8 for 200 ms:
  tone(8, 1047, 200);
  delay(200);
}
void sonar3() {
  // play a note on pin 8 for 200 ms:
  tone(8, 1047, 200);
  delay(50);
}

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Video