Revision 9:05396b551a9a, committed 2012-10-02

Comitter:

gltest26

Date:

Tue Oct 02 18:04:13 2012 +0000

Parent:

8:ac0365ab3cef

Commit message:

Added support for calibration curve on chip temperature.

Changed in this revision

--- a/ITG3200.cpp	Tue Oct 02 17:09:20 2012 +0000
+++ b/ITG3200.cpp	Tue Oct 02 18:04:13 2012 +0000
@@ -68,6 +68,17 @@
 
 }
 
+void ITG3200::setCalibrationCurve(const float offset[3], const float slope[3]){
+    if(offset){
+        for(int i = 0; i < 3; i++)
+            this->foffset[i] = offset[i];
+    }
+    if(slope){
+        for(int i = 0; i < 3; i++)
+            this->slope[i] = slope[i];
+    }
+}
+
 char ITG3200::getWhoAmI(void){
 
     //WhoAmI Register address.
@@ -242,6 +253,24 @@
         readings[i] = swapExtend(&rx[i * 2]);
 }
 
+void ITG3200::getGyroXYZ(int readings[3], Correction corr){
+    getRawGyroXYZ(readings);
+    switch(corr){
+    case OffsetCorrection:
+        for(int i = 0; i < 3; i++)
+            readings[i] -= offset[i];
+        break;
+    case Calibration:
+        {
+            float temp = getTemperature();
+            for(int i = 0; i < 3; i++)
+                readings[i] -= slope[i] * temp + foffset[i];
+        }
+        break;
+    }
+}
+
+
 char ITG3200::getPowerManagement(void){
 
     char tx = PWR_MGM_REG;

--- a/ITG3200.h	Tue Oct 02 17:09:20 2012 +0000
+++ b/ITG3200.h	Tue Oct 02 18:04:13 2012 +0000
@@ -95,6 +95,21 @@
      * the library takes care of it.  We just always clear the LSB.
      */
     static const int I2C_ADDRESS = 0xD0;
+    
+    /**
+     * @brief Zero offset correction mode that can be specified when calling getGyroXYZ().
+     *
+     * The device has a major drift in readings depending on ambient temperature.
+     * You can measure the temperature with built-in thermometer to correct it, but you
+     * must have calibration curves for each axes to do so.
+     * Here are the options on how to correct the drift.
+     */
+    enum Correction{
+        NoCorrection, ///< Do not correct zero offset at all; You would have trouble integrating the values to obtain rotation.
+        OffsetCorrection, ///< Correct the outputs with single-point zero adjust.
+        Calibration, ///< Use calibration curve (actually lines) to correct the outputs. You must provide coefficients with setCalibrationCurve().
+        Num_Correction
+    };
 
     /**
      * Constructor.
@@ -119,6 +134,14 @@
     ~ITG3200();
     
     void init();
+    
+    /**
+     * Sets calibration curve parameters.
+     *
+     * @param offset An array holding calibration curve offsets (0th-order coefficient) for each axis, must have 3 elements.
+     * @param slope An array holding calibration curve slopes (1st-order coefficient) for each axis, must have 3 elements.
+     */
+    void setCalibrationCurve(const float offset[3], const float slope[3]);
 
     /**
      * Get the identity of the device.
@@ -298,24 +321,25 @@
      * Typical sensitivity is 14.375 LSB/(degrees/sec).
      * 
      * @param readings The output buffer array that has at least 3 length.
-     * @param subtractOffset Make the returned values subtracted of zero offset.
+     * @param corr Correction method for returned values.
      */
-    void getGyroXYZ(int readings[3], bool subtractOffset = true);
+    void getGyroXYZ(int readings[3], Correction corr = OffsetCorrection);
 
     /**
      * Burst read the outputs on the x,y,z-axis gyroscope and convert them into degrees per second.
      *
      * @param readings The output buffer array that has at least 3 length.
+     * @param corr Correction method for returned values.
      */
-    void getGyroXYZDegrees(double readings[3]);
+    void getGyroXYZDegrees(double readings[3], Correction corr = OffsetCorrection);
 
     /**
      * Burst read the outputs on the x,y,z-axis gyroscope and convert them into degrees per second.
      *
      * @param readings The output buffer array that has at least 3 length.
-     * @param subtractOffset Make the returned values subtracted of zero offset.
+     * @param corr Correction method for returned values.
      */
-    void getGyroXYZRadians(double readings[3], bool subtractOffset = true);
+    void getGyroXYZRadians(double readings[3], Correction corr = OffsetCorrection);
 
     /**
      * Get the power management configuration.
@@ -455,6 +479,9 @@
      */
     int offset[3];
     
+    float foffset[3];
+    float slope[3];
+    
     long calibSamples;
     
 private:
@@ -485,24 +512,16 @@
 };
 
 
-inline void ITG3200::getGyroXYZ(int readings[3], bool subtractOffset){
-    getRawGyroXYZ(readings);
-    if(subtractOffset){
-        for(int i = 0; i < 3; i++)
-            readings[i] -= offset[i];
-    }
-}
-
-inline void ITG3200::getGyroXYZDegrees(double readings[3]){
+inline void ITG3200::getGyroXYZDegrees(double readings[3], Correction corr){
     int intData[3];
-    getGyroXYZ(intData);
+    getGyroXYZ(intData, corr);
     for(int i = 0; i < 3; i++)
         readings[i] = intData[i] * 2000. / 32767.;
 }
 
-inline void ITG3200::getGyroXYZRadians(double readings[3], bool subtractOffset){
+inline void ITG3200::getGyroXYZRadians(double readings[3], Correction corr){
     int intData[3];
-    getGyroXYZ(intData, subtractOffset);
+    getGyroXYZ(intData, corr);
     for(int i = 0; i < 3; i++)
         readings[i] = intData[i] * 2000. / 32767. * 2. * M_PI / 360.;
 }