Need a bit of help with the Sonar

[jordan11623]

Our model number is MB1222, we're unsure how to wire it and schemeatics aren't really helping. We'd like help so that we can use for the FIRST Robotics Competion. We've hooked up positive and negative, now we're kind of stuck. Specificaly, we don't know how to hook up the signal wire. Thanks.
-Team 4641

[Alan Anderson]

You've chosen a part that requires more programming support than most. http://www.maxbotix.com/Ultrasonic_Sensors/MB1222.htm says that it connects via the I2C interface. In addition to power and ground, you'll need to wire the SDA (data) and SCL (clock) pins. What language are you using to write your robot program?

[amesmich]

Heres some arduino code we used. We altered it greatly but it shoudl get you started.

/* This script is designed to take several readings from the maxbotix sonar and generate a mode/median.
Author: Jason Lessels
Date created: 2011/June/06
Lisence: GPL (=>2)
This work has been compileed using many sources mainly posts/wiki posts from;
Allen, Bruce (2009/July/23) and Gentles, Bill (2010/Nov/12)
*/ 


//Set the pin to recieve the signal.
const int pwPin = 7;
//variables needed to store values
int arraysize = 9; //quantity of values to find the median (sample size). Needs to be an odd number 


//declare an array to store the samples. not necessary to zero the array values here, it just makes the code clearer
int rangevalue[] = { 0, 0, 0, 0, 0, 0, 0, 0, 0};
long pulse;
int modE;
 void setup() { 

  //Open up a serial connection
  Serial.begin(9600);
  //Wait for the serial connection
  delay(500);



}
//Main loop where the action takes place
void loop() { 
  pinMode(pwPin, INPUT);


  for(int i = 0; i < arraysize; i++)
  {								    


    pulse = pulseIn(pwPin, HIGH);
    rangevalue[i] = pulse/58;
    delay(10);
  }


  Serial.print("Unsorted: ");
  printArray(rangevalue,arraysize);
  isort(rangevalue,arraysize);
  Serial.print("Sorted: ");
  printArray(rangevalue,arraysize);
  modE = mode(rangevalue,arraysize);
  Serial.print("The mode/median is: ");
  Serial.print(modE);
  Serial.println();
  delay(1000);


} 


/*-----------Functions------------*/ //Function to print the arrays.
void printArray(int *a, int n) { 

  for (int i = 0; i < n; i++)
  {
    Serial.print(a[i], DEC);
    Serial.print(' ');
  }


  Serial.println();


} 


//Sorting function
// sort function (Author: Bill Gentles, Nov. 12, 2010)
void isort(int *a, int n){
// *a is an array pointer function

  for (int i = 1; i < n; ++i)
  {
    int j = a[i];
    int k;
    for (k = i - 1; (k >= 0) && (j < a[k]); k--)
    {
      a[k + 1] = a[k];
    }
    a[k + 1] = j;
  }


} 


//Mode function, returning the mode or median.
int mode(int *x,int n){ 
  int i = 0;
  int count = 0;
  int maxCount = 0;
  int mode = 0;
  int bimodal;
  int prevCount = 0;


  while(i<(n-1)){


    prevCount=count;
    count=0;


    while(x[i]==x[i+1]){


      count++;
      i++;
    }


    if(count>prevCount&count>maxCount){
      mode=x[i];
      maxCount=count;
      bimodal=0;
    }
    if(count==0){
      i++;
    }
    if(count==maxCount){//If the dataset has 2 or more modes.
      bimodal=1;
    }
    if(mode==0||bimodal==1){//Return the median if there is no mode.
      mode=x[(n/2)];
    }
    return mode;
  }


}

[jordan11623]

Originally Posted by Alan Anderson

You've chosen a part that requires more programming support than most. http://www.maxbotix.com/Ultrasonic_Sensors/MB1222.htm says that it connects via the I2C interface. In addition to power and ground, you'll need to wire the SDA (data) and SCL (clock) pins. What language are you using to write your robot program?

We're writing the program in French. No, we kid. The program is Labview, I'm not really sure what the program language is... If you can help us from that point, that would be fantastic.

[Alan Anderson]

Originally Posted by jordan11623

The program is Labview, I'm not really sure what the program language is... If you can help us from that point, that would be fantastic.

Few people know that the actual name of the graphical language in the LabVIEW environment is "G". Most would just say you're programming in LabVIEW.

Why did you pick the MB1222 device? I2C is powerful, but it's one of the more complex schemes available in the MaxBotics sensor line.

If you feel up to the challenge, you can use the ADXL345 I2C Accelerometer example as a starting point. It shows how to communicate with an I2C device. The MB1222 datasheet tells what the 8-bit equivalent read and write addresses are (E0 and E1), and describes how to interpret the response.

If you aren't comfortable blazing new trails, you would find your job to be much easier if you used something like the MB1010 or MB1020 instead. Reading its output can be as simple as reading an analog voltage, something which is well supported by the FRC programming tools.