This is a simple tutorial showing how to interface HC – SR04 ultrasonic ranging module with Raspberry Pi to measure distance using JAVA. Ultrasonic ranging module HC – SR04 provides 2cm – 400cm non-contact measurement function, the ranging accuracy can reach to 3mm. The modules include ultrasonic transmitters, receiver and control circuit. The basic principle of work:
(1) Using IO trigger for at least 10us high-level signal,
(2) The Module automatically sends eight 40 kHz and detect whether there is a
pulse signal back.
(3) IF the signal back, through high level, time of high output IO duration is the time from sending ultrasonic to returning.
Links :
Java Application on Pi Playlist: http://bit.ly/2eB1O2K
Github Repository : http://bit.ly/2j95Osp
Schematic : http://bit.ly/2ihvK5F
Pi4J GPIO Numbering : http://bit.ly/2ja20av
Download Pi4J Library : http://bit.ly/2j32blF
Code : http://bit.ly/2oeMhHi
import com.pi4j.io.gpio.*;
public class Main {
//GPIO Pins
private static GpioPinDigitalOutput sensorTriggerPin ;
private static GpioPinDigitalInput sensorEchoPin ;
final static GpioController gpio = GpioFactory.getInstance();
public static void main(String [] args) throws InterruptedException{
new Main().run();
}
public void run() throws InterruptedException{
sensorTriggerPin = gpio.provisionDigitalOutputPin(RaspiPin.GPIO_00); // Trigger pin as OUTPUT
sensorEchoPin = gpio.provisionDigitalInputPin(RaspiPin.GPIO_02,PinPullResistance.PULL_DOWN); // Echo pin as INPUT
while(true){
try {
Thread.sleep(2000);
sensorTriggerPin.high(); // Make trigger pin HIGH
Thread.sleep((long) 0.01);// Delay for 10 microseconds
sensorTriggerPin.low(); //Make trigger pin LOW
while(sensorEchoPin.isLow()){ //Wait until the ECHO pin gets HIGH
}
long startTime= System.nanoTime(); // Store the surrent time to calculate ECHO pin HIGH time.
while(sensorEchoPin.isHigh()){ //Wait until the ECHO pin gets LOW
}
long endTime= System.nanoTime(); // Store the echo pin HIGH end time to calculate ECHO pin HIGH time.
System.out.println("Distance :"+((((endTime-startTime)/1e3)/2) / 29.1) +" cm"); //Printing out the distance in cm
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
}
Buy Sensor: http://amzn.to/2iJ3Z24 (India)
Buy Raspberry Pi: http://amzn.to/2jlIOUH (India)
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