update readme.md

CHANGELOG.md

@@ -7,8 +7,9 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
 ## [0.6.1] - 2024-07-25
+- redo of **calibrate()** function by Maik Menz.
 - improve initialization of gax, gay and gaz
-- add **_readRaw()** to improve calibrate()
+- add **readRaw()** to improve calibrate()
 
 
 ## [0.6.0] - 2024-06-22

GY521.cpp

@@ -72,8 +72,12 @@ void GY521::reset()
 }
 
 
-void GY521::calibrate(uint16_t times, float angleX, float angleY, bool inverted)
+bool GY521::calibrate(uint16_t times, float angleX, float angleY, bool inverted)
 {
+  //  disable throttling / caching of read values.
+  bool oldThrottle = _throttle;
+  _throttle = false;
+
   //  set all errors to zero, to get the raw reads.
   axe = aye = aze = 0;
   gxe = gye = gze = 0;
@@ -85,26 +89,32 @@ void GY521::calibrate(uint16_t times, float angleX, float angleY, bool inverted)
   //  adjust times if zero.
   if (times == 0) times = 1;
 
-  //  summarize (6x) the measurements.
+  //  sum (6x) the measurements.
+  uint16_t samples = 0;
   for (uint16_t i = 0; i < times; i++)
   {
-    _readRaw();
-    _axe -= getAccelX();
-    _aye -= getAccelY();
-    _aze -= getAccelZ();
-    _gxe -= getGyroX();
-    _gye -= getGyroY();
-    _gze -= getGyroZ();
+    if (_readRaw() == GY521_OK)
+    {
+      _axe -= getAccelX();
+      _aye -= getAccelY();
+      _aze -= getAccelZ();
+      _gxe -= getGyroX();
+      _gye -= getGyroY();
+      _gze -= getGyroZ();
+      samples++;
+    }
   }
 
+  if (samples == 0) return false;
+
   //  scale gyro calibration errors so read() should get all zero's on average.
-  float factor = _raw2dps / times;
+  float factor = _raw2dps / samples;
   gxe = _gxe * factor;
   gye = _gye * factor;
   gze = _gze * factor;
 
   //  scale accelerometer calibration errors so read() should get all zero's on average.
-  factor = _raw2g / times;
+  factor = _raw2g / samples;
   axe = _axe * factor;
   aye = _aye * factor;
   aze = _aze * factor;
@@ -118,6 +128,11 @@ void GY521::calibrate(uint16_t times, float angleX, float angleY, bool inverted)
   axe -= _gravx;
   aye -= _gravy;
   aze += inverted ? -_gravz : _gravz;
+
+  //  restore throttle state.
+  _throttle = oldThrottle;
+
+  return true;
 }
 
 

GY521.h

@@ -52,7 +52,7 @@ class GY521
   //  EXPERIMENTAL
   //  calibrate needs to be called to compensate for errors.
   //  must be called after setAccelSensitivity(as); and setGyroSensitivity(gs);
-  void     calibrate(uint16_t times, float angleX = 0, float angleY = 0, bool inverted = false);
+  bool     calibrate(uint16_t times, float angleX = 0, float angleY = 0, bool inverted = false);
 
   bool     wakeup();
   //  throttle to force delay between reads.

README.md

@@ -24,6 +24,11 @@ It needs to be tested a lot more.
 See changelog.md for latest updates.
 
 
+#### 0.6.1
+
+Improved **calibrate()** to support any angle.
+
+
 #### 0.6.0
 
 Fixed a bug in calibration function, making previous versions obsolete.
@@ -92,6 +97,10 @@ This function overwrites the values of axe aye aze gxe gye gze.
 
 Note the **calibrate()** function takes time, depending on the number of times.
 
+Since version 0.6.1 the calibrate function is extended with optional parameters so the
+sensor can be calibrated in any angle. 
+**bool calibrate(times, angleX = 0, angleY = 0, inverted = false)**
+
 
 #### Manual calibration
 
@@ -120,14 +129,24 @@ Note call **Wire.begin()** before **begin()**.
 
 ### Calibrate
 
-- **void calibrate(uint16_t times)** This function overwrites the values of axe aye aze gxe gye gze.
-To get "quality error" offsets, the GY521 sensor should not move during the calibration.
-The parameter times determines the number of measurements made.
-Typical values are 100 or more.
-Please note this is a time consuming function.
+- **bool calibrate(uint16_t times, float angleX = 0, float angleY = 0, bool inverted = false)** 
+This function overwrites the values of axe aye aze and gxe gye gze.
+To improve the quality of the error offsets, the GY521 sensor should not move during the calibration.
+The parameter times determines the number of measurements the calibration function should make.
+Note that the actual number of samples can be less if a read of the sensor fails.
+If there is no good read at all the function returns **false**.
+Typical values for times are 100 or more. 
+If times is set to 0, it will be forced to 1.
+Please note this call will be very time consuming.
 
 Ideal the function **calibrate()** should continue until it is stable (how to define) for n reads.
-Drawback is that this would make the duration unpredictable. 
+Drawback is that this would make the duration unpredictable.
+
+New since 0.6.1 (experimental)  
+The optional parameters **float angleX = 0, float angleY = 0** should be between -90 .. +90.
+These can be used if the sensor is not lying flat during calibration. 
+The optional parameter **bool inverted = false** should be set to true if the sensor is 
+upside down. 
 
 
 ### Throttle
@@ -293,7 +312,9 @@ However if one specific is needed, please open an issue.
 
 #### Should
 
-- test **calibrate()** function for different sensitivities.
+- test **calibrate()** function 
+  - for different sensitivities.
+  - for different angles.
 
 #### Could
 

library.json

@@ -8,6 +8,9 @@
       "name": "Rob Tillaart",
       "email": "[email protected]",
       "maintainer": true
+    },
+    {
+      "name": "Maik Menz",
     }
   ],
   "repository":