MaxSonar EZ0 Problems

I have tried almost every variation of the code I can find. I tried the code supplied by the Arduino Playground.

"http://www.arduino.cc/en/Tutorial/UltrasoundSensor - I just wanted to point out that this code also works for the Maxbotix Max Sonar ultrasonic range finder... which is sold in the USA through SparkFun Electronics... "

Which I cant get to work properly. We have a parallax ping sensor that works with this code but out MaxSonar EZ0 does not even with modification. I should also tell you the reasons we are trying this sensor is because of the parallax range limitations.

We have the code kinda working but the distance is severely limited 1in to about 20in not the 255avaliable in the specs.

You can also see where we are trying to switch and try the other ports on the sensor the analog pin gives a reading of 0. The only reading that kinda works is the PM pin.

Can anyone help?

int pingPin = 7;
//int analogPin = 5;

void setup()
{
  Serial.begin(9600);
}

void loop()
{
  long duration, inches, cm;

  // The PING))) is triggered by a HIGH pulse of 2 or more microseconds.
  // We 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);

 /* pinMode(analogPin, OUTPUT);
  analogWrite(analogPin, LOW);
  delayMicroseconds(2);
  analogWrite(analogPin, HIGH);
  delayMicroseconds(5);
  analogWrite(analogPin, 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;
}

I've used those sensors plenty and they work well.

The problem is probably something to do with where you have it positioned: if there is anything in the beam path of the sensor, it will reflect back. If it's on a table for example, the tabletop will reflect back the Ultrasound and it will appear to only read to 20 inches.

To troubleshoot this, I would connect a voltmeter to the analog output, and then position the sensor so that you get the full output range. After that I would just use analogRead() to get the sensor value.

D