ULTRASONIC SENSOR HC-SRO4 WITH ARDUINO

This program for interfacing Arduino with ultra sonic sensor with Arduino.

Technical Details

1. Working Voltage : 5V(DC)
2. Static current: Less than 2mA.
3. Output signal: Electric frequency signal, high level 5V, low level 0V.
4. Sensor angle: Not more than 15 degrees.
5. Detection distance: 2cm-450cm.
6. High precision: Up to 0.3cm
7. Input trigger signal: 10us TTL impulse
8. Echo signal : output TTL PWM signal

Mode of connection

1. VCC
2. trig(T)
3. echo(R)
4. GND

Program

/*
                     -------calculation-----------
                     speed of sound = 340.29 m/sec.
                     Here the total distance travelled by sound = sum of
                     distance from sensor to object and object to sensor.
                     But both are same . so we need only one distance.
                     then speed become 170.15 m/sec.
                     converts m/sec to cm/microseconds.
                     then (170*100)/1000000 = 0.01715cm/us.
                     from above equation time taken to
                     travel distance 1CM= 1/0.01715cm = 58.3us.
                     then distance = duration of received pulse / 58.3
                      HC-SR04 sensor pinouts to arduino:
                      VCC to arduino 5v
                      GND to arduino GND
                      Echo to Arduino pin 7
                      Trig to Arduino pin 8
                      result 0 indicates out of range condition
                      */
                     char g[4];unsigned int a,duration;
                     #define echoPin 7 // Echo Pin
                     #define trigPin 8 // Trigger Pin
                     void setup()
                     {
                      Serial.begin (9600);
                      pinMode(trigPin, OUTPUT);
                      pinMode(echoPin, INPUT);
                     }
                     void loop()
                     {
                      digitalWrite(trigPin, LOW);
                      digitalWrite(trigPin, HIGH); //sends signal 10 us to excite ultra sonic sensor
                      delayMicroseconds(10);
                      digitalWrite(trigPin, LOW);
                      duration = pulseIn(echoPin, HIGH);//reads  duartion pulse in Microseconds
                      a = duration/58;
                      inttoascii();
                      Serial.write('D'); //it indicate start of data.Not necessary
                      Serial.print(g); //distance in CM
                      Serial.write(0xd); //new line
                      delay(50); //Delay 50ms before next reading.
                     }
                     void inttoascii ()
                     {
                     g[3]=' ';
                     g[2]=(a%10)+0x30;
                     g[1]=a/10%10+0x30;
                     g[0]=a/100%10+0x30;//MSB section
                     }