Ultrasonic Distance Sensor HC-SR04.docx

Ultrasonic Distance Sensor HC-SR04

·         Price: Rs.525.00 including Taxes

Description

The HC SR04 is an inexpensive ultrasonic distance sensor.
Specifications:
power supply :5V DC
quiescent current : <2mA
effectual angle: <15°
ranging distance : 2cm – 500 cm
resolution : 0.3 cm
Works with Arduino

Sample Arduino Code
/* HC-SR04
A Simple Modified version of the Ping Sensor Program t

*/

// this constant won't change. It's the pin number
// of the sensor's output / trigger
const int echo = 8, Trig = 9;

void setup() {
// initialize serial communication:
Serial.begin(9600);
pinMode(Trig, OUTPUT);
pinMode(echo, INPUT);
}

void loop()
{
// establish variables for duration of the ping,
// and the distance result in inches and centimeters:
long duration, inches, cm;

// The PING))) is triggered by a HIGH pulse of 10 microseconds.
// Give a short LOW pulse beforehand to ensure a clean HIGH pulse:

digitalWrite(Trig, LOW);
delayMicroseconds(2);
digitalWrite(Trig, HIGH);
delayMicroseconds(10);
digitalWrite(Trig, LOW);

// The echo pin is used to read the signal from the PING))): a HIGH
// pulse whose duration is the time (in microseconds) from the sending
// of the ping to the reception of its echo off of an object.

duration = pulseIn(echo, HIGH);

// convert the time into a distance
inches = microsecondsToInches(duration);
cm = microsecondsToCentimeters(duration);

Serial.print(inches);
Serial.print("in, ");
Serial.print(cm);
Serial.print("cm");
Serial.println();

delay(100);
}

long microsecondsToInches(long microseconds)
{
// According to Parallax's datasheet for the PING))), there are
// 73.746 microseconds per inch (i.e. sound travels at 1130 feet per
// second). This gives the distance travelled by the ping, outbound
// and return, so we divide by 2 to get the distance of the obstacle.
return microseconds / 74 / 2;
}

long microsecondsToCentimeters(long microseconds)
{
// The speed of sound is 340 m/s or 29 microseconds per centimeter.
// The ping travels out and back, so to find the distance of the
// object we take half of the distance travelled.
return microseconds / 29 / 2;
}