Ultrasonic Sensor (HC-SR04) With Arduino

Overview
Ultrasonic Sensor allow you measure the distance to an object by using sound waves. It measures distance by sending out (transmitter) a sound wave at a specific frequency and listening (receiver) for that sound wave to bounce back.

Reading PIR Sensors

The HC-SR04 Ultrasonic Module has 4 pins, Ground, VCC, Trig and Echo. The Ground and the VCC pins of the module needs to be connected to the Ground and the 5 volts pins on the Arduino Board respectively and the trig and echo pins to any Digital I/O pin on the Arduino Board.

In principle, the operation is as follows:

1. sends a ping sound Trigger pin
2. If an obstacle is trapped the wave is reflected back.
3. the Echo pin receive the signal returned

The time taken allows us to determine the distance between the sensor and the barrier.

connection with Arduino:

Arduino Pin	Sensor Pin
POWER 5V	VCC
Digital 7	Trig
Digital 8	Echo
GND	GND

Code

/*
* Ultrasonic Sensor HC-SR04 and Arduino
*
*
*/
// defines pins numbers
const int trigPin = 7;
const int echoPin = 8;
// defines variables
long duration;
int distance;
void setup() {
pinMode(trigPin, OUTPUT); // Sets the trigPin as an Output
pinMode(echoPin, INPUT); // Sets the echoPin as an Input
Serial.begin(9600); // Starts the serial communication
}
void loop() {
// Clears the trigPin
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
// Sets the trigPin on HIGH state for 10 micro seconds
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
// Reads the echoPin, returns the sound wave travel time in microseconds
duration = pulseIn(echoPin, HIGH);
// Calculating the distance
distance= duration*0.034/2;
// Prints the distance on the Serial Monitor
Serial.print("Distance: ");
Serial.println(distance);
}