/*Distance Tracker*/


#define trigPin 12 // define TrigPin
#define echoPin 11 // define EchoPin.
#define MAX_DISTANCE 200 // Maximum sensor distance is rated at 400-500cm.
// define the timeOut according to the maximum range. timeOut= 2*MAX_DISTANCE /100 /340 *1000000 = MAX_DISTANCE*58.8
float timeOut = MAX_DISTANCE * 60;
int soundVelocity = 340; // define sound speed=340m/s


void setup() {
 pinMode(trigPin,OUTPUT);// set trigPin to output mode
 pinMode(echoPin,INPUT); // set echoPin to input mode
 Serial.begin(9600);    // Open serial monitor at 9600 baud to see ping results.
}


void loop() {
 delay(100); // Wait 100ms between pings (about 20 pings/sec). 29ms should be the shortest delay between pings.
 Serial.print("Ping: ");
 Serial.print(getSonar()); // Send ping, get distance in cm and print result (0 = outside set distance range)
 Serial.println("cm");
}


float getSonar() {
 unsigned long pingTime;
 float distance;
 digitalWrite(trigPin, HIGH); // make trigPin output high level lasting for 10μs to triger HC_SR04,
 delayMicroseconds(10);
 digitalWrite(trigPin, LOW);
 pingTime = pulseIn(echoPin, HIGH, timeOut); // Wait HC-SR04 returning to the high level and measure out this waitting time
 distance = (float)pingTime * soundVelocity / 2 / 10000; // calculate the distance according to the time
 return distance; // return the distance value
}