Introduction: Easy Ultrasonic 4-pin Sensor Monitoring (hc-sr04)

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hello Instructables,

I have had some trouble with my cheap ultrasonic sensor (hc-sr04) and today I found a really easy solution.

It is a really simple edit of the normal 3pin code.

I added the 4 int's to the beginning of the code, so you can changes the arduino pins very easily.

The new code(4pin):

int vcc = 2; //attach pin 2 to vcc
int trig = 3; // attach pin 3 to Trig
int echo = 4; //attach pin 4 to Echo
int gnd = 5; //attach pin 5 to GND
void setup() {
pinMode (vcc,OUTPUT);
 pinMode (gnd,OUTPUT);
 // initialize serial communication:
 Serial.begin(9600);
 }
 
 void loop()
 {
 digitalWrite(vcc, HIGH);
 // 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(trig, OUTPUT);
 digitalWrite(trig, LOW);
 delayMicroseconds(2);
 digitalWrite(trig, HIGH);
 delayMicroseconds(5);
 digitalWrite(trig, LOW);
 
 // 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(echo,INPUT);
 duration = pulseIn(echo, 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:  http://www.parallax.com/dl/docs/prod/acc/28015-PI...
 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;
 }

Step 1: 3-pin Code

Code
/* Ping))) Sensor

   This sketch reads a PING))) ultrasonic rangefinder and returns the
   distance to the closest object in range. To do this, it sends a pulse
   to the sensor to initiate a reading, then listens for a pulse
   to return.  The length of the returning pulse is proportional to
   the distance of the object from the sensor.

   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

   http://www.arduino.cc/en/Tutorial/Ping

   created 3 Nov 2008
   by David A. Mellis
   modified 30 Aug 2011
   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(5);
  digitalWrite(pingPin, LOW);

  // 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: http://www.parallax.com/dl/docs/prod/acc/28015-PING-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;
}

Step 2: Trouble With the Sensor/troubleshooting

So there have been many questions about failing sensors and no output. Here are some solutions.

1) Dubble check the connection.

2) check your power source: Sometimes usb connections or 9v batteries do not deliver enough power for sensors and motors/servos. So check the output with only the sensor before you upload your final code. A bigger battery might come in handy too.

3) Use other ports: First of try using a different usb port on your computer and restart the program. Second of try using other pins to attach the sensor to the arduino

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