Hi,
First, make sure your right connection. You can choose a pin for receiver, for example pin7.
I will tell you something about your code.
1.
int wrtpingstate=digitalRead(pingPin); //capture state 20 us after write
pinMode(pingPin, INPUT)
Make the pin output mode before you read it. The pin will have a high signa when there is a Ultra Sonic signal. So you’d better use “int wrtpingstate=pulseIn(pingPin, HIGH);//capture state 20 us after write” . But you can’t read it twice.
2. Make the code in looping so that you can read the data more time. l have test your code and correct something.
const int pingPin = 7;
void setup() {
Serial.begin(9600);
// initialize serial communication:
}
void loop()
{
pinMode(pingPin, OUTPUT);
digitalWrite(pingPin, LOW);
delayMicroseconds(2);
digitalWrite(pingPin, HIGH);
delayMicroseconds(15);
digitalWrite(pingPin, LOW);
delayMicroseconds(20);
//int wrtpingstate=pulseIn(pingPin, HIGH);//capture state 20 us after write
pinMode(pingPin, INPUT);
int initpingstate=pulseIn(pingPin, HIGH); //capture state after pinpode(input);
//Serial.print("after write pingpin is: "); Serial.println(wrtpingstate);
Serial.print("after pinmode input pingpin is: "); Serial.println(initpingstate);
// while(true);//You don’t need wait for the signal.
delay(100);
}
- Here is a code, you can refer to it.
/* The circuit:
* +V connection of the PING))) attached to +5V
* GND connection of the PING))) attached to ground
* SIG connection of the PING))) attached to digital pin 7
arduino.cc/en/Tutorial/Ping
created 3 Nov 2008
by David A. Mellis
modified 30 Jun 2009
by Tom Igoe
This example code is in the public domain.
*/
// this constant won’t change. It’s the pin number
// of the sensor’s output:
const int pingPin = 7;
void setup() {
// initialize serial communication:
Serial.begin(9600);
}
void loop()
{
// establish variables for duration of the ping,
// and the distance result in inches and centimeters:
long duration, inches, cm;
// The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
// Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
pinMode(pingPin, OUTPUT);
digitalWrite(pingPin, LOW);
delayMicroseconds(2);
digitalWrite(pingPin, HIGH);
delayMicroseconds(15);
digitalWrite(pingPin, LOW);
delayMicroseconds(20);
// The same pin is used to read the signal from the PING))): a HIGH
// pulse whose duration is the time (in microseconds) from the sending
// of the ping to the reception of its echo off of an object.
pinMode(pingPin, INPUT);
duration = pulseIn(pingPin, HIGH);
// convert the time into a distance
inches = microsecondsToInches(duration);
cm = microsecondsToCentimeters(duration);
Serial.print(inches);
Serial.print("in, ");
Serial.print(cm);
Serial.print(“cm”);
Serial.println();
delay(100);
}
long microsecondsToInches(long microseconds)
{
// According to Parallax’s datasheet for the PING))), there are
// 73.746 microseconds per inch (i.e. sound travels at 1130 feet per
// second). This gives the distance travelled by the ping, outbound
// and return, so we divide by 2 to get the distance of the obstacle.
// See: parallax.com/dl/docs/prod/ac … G-v1.3.pdf
return microseconds / 74 / 2;
}
long microsecondsToCentimeters(long microseconds)
{
// The speed of sound is 340 m/s or 29 microseconds per centimeter.
// The ping travels out and back, so to find the distance of the
// object we take half of the distance travelled.
return microseconds / 29 / 2;
}
