Maxbotix MaxSonar EZ1

Forum 2005-2010 (read only) Hardware Interfacing
1

This untrasonic range finder has serial, analog voltage and pulse width ouputs and I can't understand how to use any of them properly.

The serial output apparently gives data in RS232 format (what is that?) and when I just send the data to my computer I get lots of -1 and a few other numbers occasionally.

The analog output is apparently (vcc/512) per inch about 9.8mV per inch for 5v but how can I code fot this?

The pulse width output is 147uS per inch but I would also have no idea of how to code this.

Can anyone help?

Mowcius

2

The analog output is apparently (vcc/512) per inch about 9.8mV per inch for 5v but how can I code fot this?

The pulse width output is 147uS per inch but I would also have no idea of how to code this.

http://arduino.cc/en/Reference/PulseIn

Dig around the forum - these are common devices, and these questions have been asked before.

3

I had a look through the forums and found a bit. I was more interested in using the serial but I haven't found anything on using that.

Mowcius

4

There was a recent thread about that too, IIRC.

5

Do you know where that thread would happen to be? I have had a long hard search and I cannot find it...

6

Don't know - I seem to remember a discussion about logic levels and whether or not the levels were RS232 compatible or not.

The search facility sucks badly.

7

http://www.robotshop.us/PDF/LV-MaxSonar-EZ1-Datasheet.pdf

The section on the serial i/f suggests that simple mods (inversion) to the software serial library would allow communication with the device.

8

This thread is half a year old... still, I wanted to share the info here. At first, I had thought about using one inverter and MAX232 to go from the EZ3 to RS232 levels and another MAX232 to go back to Arduino levels, but then I decided to try what AWOL suggested and modify some code from SoftwareSerial. They work great now! The code is here:

http://giesler.biz/~bjoern/blog/?p=201

My only worry is that serial communication at 9600bps is actually pretty slow. It takes more than 4ms to get one measurement from an EZ3!

9

Got it working first try, but that's got to be beginner's luck.

the hardware interface is extremely simple:
gnd, 5v and wire the PW pin on the EZ-1 to digital pin 5 on the Arduino.

Here's the code:

/*
MaxSonar_EZ1 Test
 SummitBid Technologies 2010
 */
const int sonarSensorPin = 5;
const int ledPin = 13;

long value = 0;
int cm = 0;
int inches = 0;

void setup()
{
  Serial.begin(9600);
  pinMode(ledPin, OUTPUT);

}

void loop()
{
  // Read the value from the sensor pin
  value = pulseIn(sonarSensorPin, HIGH);
  cm = value / 58;    // pulse width is 58 microsecs per cm
  inches = value / 147;     // which is 147 microeconds per inch 
  Serial.print("cm : inches = ");
  Serial.print(cm);
  Serial.print(':');
  Serial.println(inches);
  digitalWrite(ledPin, HIGH);
  delay(cm * 10);
  digitalWrite(ledPin, LOW);
  delay (cm * 10 );
  delay(20);

}

So far the only issue I have is with some false positives. Working on it.