/* Ultrasonic Ranging
Library for HC-SR04 Ultrasonic Ranging Module.librar
created 2011
by Robi.Wang
www.Elecfreak.com
*/
#define CM 1 //Centimeter
#define INC 0 //Inch
#define TP 8 //Trig_pin
#define EP 9 //Echo_pin
void setup(){
pinMode(TP,OUTPUT); // set TP output for trigger
pinMode(EP,INPUT); // set EP input for echo
Serial.begin(9600); // init serial 9600
Serial.println("-------------------Ultra_Demo_Start---------------------------------");
}
void loop(){
long microseconds = TP_init();
Serial.print("ret="); //
Serial.println(microseconds);
long distacne_cm = Distance(microseconds, CM);
Serial.print("Distacne_CM = ");
Serial.println(distacne_cm);
delay(3000);
}
long Distance(long time, int flag)
{
/*
*/
long distacne;
if(flag)
distacne = time /29 / 2 ; // Distance_CM = ((Duration of high level)*(Sonic :340m/s))/2
// = ((Duration of high level)*(Sonic :0.034 cm/us))/2
// = ((Duration of high level)/(Sonic :29.4 cm/us))/2
else
distacne = time / 74 / 2; // INC
return distacne;
}
long TP_init()
{
digitalWrite(TP, LOW);
delayMicroseconds(2);
digitalWrite(TP, HIGH); // pull the Trig pin to high level for more than 10us impulse
delayMicroseconds(10);
digitalWrite(TP, LOW);
long microseconds = pulseIn(EP,HIGH); // waits for the pin to go HIGH, and returns the length of the pulse in microseconds
return microseconds; // return microseconds
}
