SparkFun Blocks for Intel® Edison - 9 Degrees of Freedom Block

Contributors: Shawn Hymel, CaseyTheRobot, SFUptownMaker

C++ Code Examples

We're assuming that you're using the Eclipse IDE as detailed in our Beyond Arduino tutorial. If you aren't, you'll need to read over that tutorial to get up to speed.

Getting Started

Follow the instructions in the programming tutorial to create a new project named "SparkFun_9DOF_Edison_Block_Example". Once you've created the project, open the project files on disk (hint: you can find the path to the project by choosing "Properites" from the project menu), and copy the three source files found in the Edison 9DOF Block CPP library GitHub repository into the "src" directory.

Code

Everything you need to know is in the comments.

language:c
#include "mraa.hpp"
#include <iostream>
#include <unistd.h>
#include "SFE_LSM9DS0.h"
using namespace std;

int main()
{
  LSM9DS0 *imu;
  imu = new LSM9DS0(0x6B, 0x1D);
  // The begin() function sets up some basic parameters and turns the device
  //  on; you may not need to do more than call it. It also returns the "whoami"
  //  registers from the chip. If all is good, the return value here should be
  //  0x49d4. Here are the initial settings from this function:
  //  Gyro scale:        245 deg/sec max
  //  Xl scale:          4g max
  //  Mag scale:         2 Gauss max
  //  Gyro sample rate:  95Hz
  //  Xl sample rate:    100Hz
  //  Mag sample rate:   100Hz
  // These can be changed either by calling appropriate functions or by
  //  pasing parameters to the begin() function. There are named constants in
  //  the .h file for all scales and data rates; I won't reproduce them here.
  //  Here's the list of fuctions to set the rates/scale:
  //  setMagScale(mag_scale mScl)      setMagODR(mag_odr mRate)
  //  setGyroScale(gyro_scale gScl)    setGyroODR(gyro_odr gRate)
  //  setAccelScale(accel_scale aScl)  setGyroODR(accel_odr aRate)
  // If you want to make these changes at the point of calling begin, here's
  //  the prototype for that function showing the order to pass things:
  //  begin(gyro_scale gScl, accel_scale aScl, mag_scale mScl, 
  //                gyro_odr gODR, accel_odr aODR, mag_odr mODR)
  uint16_t imuResult = imu->begin();
  cout<<hex<<"Chip ID: 0x"<<imuResult<<dec<<" (should be 0x49d4)"<<endl;

  bool newAccelData = false;
  bool newMagData = false;
  bool newGyroData = false;
  bool overflow = false;

  // Loop and report data
  while (1)
  {
    // First, let's make sure we're collecting up-to-date information. The
    //  sensors are sampling at 100Hz (for the accelerometer, magnetometer, and
    //  temp) and 95Hz (for the gyro), and we could easily do a bunch of
    //  crap within that ~10ms sampling period.
    while ((newGyroData & newAccelData & newMagData) != true)
    {
      if (newAccelData != true)
      {
        newAccelData = imu->newXData();
      }
      if (newGyroData != true)
      {
        newGyroData = imu->newGData();
      }
      if (newMagData != true)
      {
        newMagData = imu->newMData(); // Temp data is collected at the same
                                      //  rate as magnetometer data.
      } 
    }

    newAccelData = false;
    newMagData = false;
    newGyroData = false;

    // Of course, we may care if an overflow occurred; we can check that
    //  easily enough from an internal register on the part. There are functions
    //  to check for overflow per device.
    overflow = imu->xDataOverflow() | 
               imu->gDataOverflow() | 
               imu->mDataOverflow();

    if (overflow)
    {
      cout<<"WARNING: DATA OVERFLOW!!!"<<endl;
    }

    // Calling these functions causes the data to be read from the IMU into
    //  10 16-bit signed integer public variables, as seen below. There is no
    //  automated check on whether the data is new; you need to do that
    //  manually as above. Also, there's no check on overflow, so you may miss
    //  a sample and not know it.
    imu->readAccel();
    imu->readMag();
    imu->readGyro();
    imu->readTemp();

    // Print the unscaled 16-bit signed values.
    cout<<"-------------------------------------"<<endl;
    cout<<"Gyro x: "<<imu->gx<<endl;
    cout<<"Gyro y: "<<imu->gy<<endl;
    cout<<"Gyro z: "<<imu->gz<<endl;
    cout<<"Accel x: "<<imu->ax<<endl;
    cout<<"Accel y: "<<imu->ay<<endl;
    cout<<"Accel z: "<<imu->az<<endl;
    cout<<"Mag x: "<<imu->mx<<endl;
    cout<<"Mag y: "<<imu->my<<endl;
    cout<<"Mag z: "<<imu->mz<<endl;
    cout<<"Temp: "<<imu->temperature<<endl;
    cout<<"-------------------------------------"<<endl;

    // Print the "real" values in more human comprehensible units.
    cout<<"-------------------------------------"<<endl;
    cout<<"Gyro x: "<<imu->calcGyro(imu->gx)<<" deg/s"<<endl;
    cout<<"Gyro y: "<<imu->calcGyro(imu->gy)<<" deg/s"<<endl;
    cout<<"Gyro z: "<<imu->calcGyro(imu->gz)<<" deg/s"<<endl;
    cout<<"Accel x: "<<imu->calcAccel(imu->ax)<<" g"<<endl;
    cout<<"Accel y: "<<imu->calcAccel(imu->ay)<<" g"<<endl;
    cout<<"Accel z: "<<imu->calcAccel(imu->az)<<" g"<<endl;
    cout<<"Mag x: "<<imu->calcMag(imu->mx)<<" Gauss"<<endl;
    cout<<"Mag y: "<<imu->calcMag(imu->my)<<" Gauss"<<endl;
    cout<<"Mag z: "<<imu->calcMag(imu->mz)<<" Gauss"<<endl;
    // Temp conversion is left as an example to the reader, as it requires a
    //  good deal of device- and system-specific calibration. The on-board
    //  temp sensor is probably best not used if local temp data is required!
    cout<<"-------------------------------------"<<endl;
    sleep(1);
  }

  return MRAA_SUCCESS;
}