HC-SR04 is a cheap and easy to use Ultrasonic Sensor, it is especially useful for robotics. The sensor pretty much contain 4 pins: VCC (5 V), Trig, Echo, GND.
For wiring, pretty much wire VCC to your micro-controller’s 5V power supply pin and GND to ground. For Trig and Echo, just wire them to a free Digital Pin.
Here’s the code for using it with an Arduino:
//Ultrasound Sensor Script for HC-SR04
#define trig_pin 13
#define echo_pin 12
void setup()
{
pinMode(trig_pin, OUTPUT);
pinMode(echo_pin, INPUT);
Serial.begin(9600);
}
void loop()
{
double dt = activate_ultrasound();
double distance = calculate_distance(dt);
Serial.print("Distance: ");
Serial.print(distance);
Serial.println(" cm");
delay(100);
}
double activate_ultrasound()
{
//Creating a 10 Microseconds pulse to activate sensor
digitalWrite(trig_pin, LOW);
digitalWrite(trig_pin, HIGH);
delayMicroseconds(10);
digitalWrite(trig_pin, LOW);
//Return time before Recieving Echo Signal in Microseconds
//Divide by 2 to get time of signal traveling one way
return pulseIn(echo_pin, HIGH)/2;
}
double calculate_distance(double time)
{
//Speed of Sound = 340.29 m/s
double speedSound = 340.29 * pow(10,-6);
double distance = time * speedSound;
//Convert meters to centimeters
distance = distance * 100;
return distance;
}
Billwaa's Blog 
Could you port this to JSSC? Still learning JSSC my self.
Something of the sort
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
package sonar;
import jssc.SerialPort;
import jssc.SerialPortException;
/**
*
* @author Z
*/
public class Sonar {
/**
* @param args the command line arguments
*/
public static void main(String[] args) throws InterruptedException {
// TODO code application logic here
SerialPort serialPort = new SerialPort(“COM5”);
try {
serialPort.openPort();//Open serial port
serialPort.setParams(SerialPort.BAUDRATE_9600,
SerialPort.DATABITS_8,
SerialPort.STOPBITS_1,
SerialPort.PARITY_NONE);//Set params. Also you can set params by this string: serialPort.setParams(9600, 8, 1, 0);
for (int i = 0; i < args.length; i++) {
serialPort.writeBytes("This is a test string".getBytes());//Write data to port
// serialPort.closePort();//Close serial port
double dt = activate_ultrasound();
double distance = calculate_distance(dt);
System.out.println("Distance: ");
System.out.println(distance);
System.out.println(" cm");
byte[] buffer = serialPort.readBytes(10);//Read 10 bytes from serial port
System.out.println(buffer);
}
serialPort.closePort();//Close serial port
} catch (SerialPortException ex) {
System.out.println(ex);
}
}
double activate_ultrasound() {
//Creating a 10 Microseconds pulse to activate sensor
digitalWrite(trig_pin, LOW);
digitalWrite(trig_pin, HIGH);
Thread.sleep(10);
digitalWrite(trig_pin, LOW);
//Return time before Recieving Echo Signal in Microseconds
//Divide by 2 to get time of signal traveling one way
return pulseIn(echo_pin, HIGH) / 2;
}
double calculate_distance(double time) {
//Speed of Sound = 340.29 m/s
double speedSound = 340.29 * Math.pow(10, -6);
double distance = time * speedSound;
//Convert meters to centimeters
distance = distance * 100;
return distance;
}
}
hmm… this look like you merged the Arduino code with the Java code, idk if this is the best idea. For me, I would merge the ultrasonic detection code with the Arduino jSSC code. Basically use the Arduino as a data acquisition device and then send the data back to PC through Serial. I would then write a program in java on the PC side to read the info. Much like this:
But again, I am not that advance in computer science. You could be totally correct and that I just don’t know what I am talking about =D
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