fix

CHANGELOG.md

@@ -7,9 +7,15 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 
 ## [0.5.2] - 2024-01-16
-- fix #48, update example
-- add some tables to readme.md
-- minor edits
+- fix #48, use float variables in example GY521_test_1.ino
+- add **void calibrate(uint16_t times)** to API
+- add **GY521_performance_calibrate.ino** example
+- add **GY521_raw_cooked.ino** example
+- make explicit that pitch roll yaw is work in progress.
+- update readme.md
+  - calibrate section
+  - add some tables
+- minor edits in examples
 
 
 ## [0.5.1] - 2023-12-11

GY521.cpp

@@ -66,6 +66,41 @@ void GY521::reset()
 }
 
 
+void GY521::calibrate(uint16_t times)
+{
+  //  disable throttling / caching of read values.
+  bool oldThrottle = _throttle;
+  _throttle = false;
+
+  //  set errors to zero
+  axe = aye = aze = 0;
+  gxe = gye = gze = 0;
+
+  for (uint16_t i = 0; i < times; i++)
+  {
+    read();
+    axe -= getAccelX();
+    aye -= getAccelY();
+    aze -= getAccelZ();
+    gxe -= getGyroX();
+    gye -= getGyroY();
+    gze -= getGyroZ();
+  }
+
+  //  adjust calibration errors so table should get all zero's.
+  float factor = 1.0 / times;
+  axe *= factor;
+  aye *= factor;
+  aze *= factor;
+  gxe *= factor;
+  gye *= factor;
+  gze *= factor;
+
+  //  restore throttle state
+  _throttle = oldThrottle;
+}
+
+
 bool GY521::wakeup()
 {
   _wire->beginTransmission(_address);
@@ -138,6 +173,7 @@ int16_t GY521::read()
   float _ay2 = _ay * _ay;
   float _az2 = _az * _az;
 
+  //  calculate angle
   _aax = atan(       _ay / sqrt(_ax2 + _az2)) * GY521_RAD2DEGREES;
   _aay = atan(-1.0 * _ax / sqrt(_ay2 + _az2)) * GY521_RAD2DEGREES;
   _aaz = atan(       _az / sqrt(_ax2 + _ay2)) * GY521_RAD2DEGREES;
@@ -159,10 +195,13 @@ int16_t GY521::read()
   _gy += gye;
   _gz += gze;
 
+  //  integrate gyroscope data
   _gax += _gx * duration;
   _gay += _gy * duration;
   _gaz += _gz * duration;
 
+  //  experimental below this line.
+  //  Pitch Roll Yaw are work in progress
   //  normalize
   //  _gax etc might loose precision after many iterations #36
   if (_normalize)
@@ -250,6 +289,7 @@ int16_t GY521::readAccel()
   float _ay2 = _ay * _ay;
   float _az2 = _az * _az;
 
+  //  calculate angles.
   _aax = atan(       _ay / sqrt(_ax2 + _az2)) * GY521_RAD2DEGREES;
   _aay = atan(-1.0 * _ax / sqrt(_ay2 + _az2)) * GY521_RAD2DEGREES;
   _aaz = atan(       _az / sqrt(_ax2 + _ay2)) * GY521_RAD2DEGREES;
@@ -318,6 +358,7 @@ int16_t GY521::readGyro()
   _gaz += _gz * duration;
 
 
+  //  experimental below this line.
   //  normalize
   //  _gax etc might loose precision after many iterations #36
   if (_normalize)

GY521.h

@@ -44,6 +44,10 @@ class GY521
   bool     isConnected();
   void     reset();
 
+  //  EXPERIMENTAL
+  //  calibrate needs to be called to compensate for errors.
+  //  must be called after setAccelSensitivity(as); and setGyroSensitivity(gs);
+  void     calibrate(uint16_t times);
 
   bool     wakeup();
   //  throttle to force delay between reads.
@@ -90,6 +94,9 @@ class GY521
   float    getGyroX()    { return _gx; };
   float    getGyroY()    { return _gy; };
   float    getGyroZ()    { return _gz; };
+
+  //  EXPERIMENTAL
+  //  pitch, roll and yaw is work in progress.
   float    getPitch()    { return _pitch; };
   float    getRoll()     { return _roll; };
   float    getYaw()      { return _yaw; };

README.md

@@ -16,13 +16,14 @@ Arduino library for I2C GY521 accelerometer-gyroscope sensor a.k.a. MCU-6050.
 
 ## Description
 
-Experimental library for GY521 a.k.a. MCU-6050.
+**Experimental** library for GY521 a.k.a. MCU-6050.
 
 Library is work in progress, in fact it is extracted and extended from an old project.
 It needs to be tested a lot more.
 
 See changelog.md for latest updates.
 
+
 #### 0.5.0 Breaking change
 
 Version 0.5.0 introduced a breaking change.
@@ -37,10 +38,22 @@ before calling **begin()**.
 - **GY521_angle** read angleX, angleY, angleZ.
 - **GY521_performance** measure performance.
 - **GY521_pitch_roll_yaw** to get pitch roll yaw.
-- **GY521_readCalibration_1** read calibration values / errors for a flat sensor.
+- **GY521_raw_cooked** make a table of raw measurements and derived data 
+for analysis e.g. in a spreadsheet.
+- **GY521_readCalibration_1** read calibration values / errors for a "flat" sensor.
 - **GY521_readCalibration_2** generate calibration code snippet.
 - **GY521_test_1** test working of the sensor.
-- **GY521_test_2** test set/get functions.
+- **GY521_test_2** test set/get functions (sort of unit test).
+- **GY521_two_sensors** demo for two sensors.
+
+
+#### Related
+
+- https://invensense.tdk.com/wp-content/uploads/2015/02/MPU-6000-Datasheet1.pdf
+- https://cdn.sparkfun.com/datasheets/Sensors/Accelerometers/RM-MPU-6000A.pdf  register map.
+- https://github.com/RobTillaart/Angle
+- https://github.com/RobTillaart/AngleConverter
+
 
 
 ## Breakout board
@@ -67,6 +80,11 @@ AD0 connected to VCC => 0x69
 
 ## Calibration (short version for now)
 
+Since version 0.5.2 the library has a build in **void calibrate(times)** function which
+can be called instead of manual copying.
+This function overwrites the values of axe aye aze gxe gye gze.
+**calibrate()** must be called after **setAccelSensitivity(as)** and **setGyroSensitivity(gs)**.
+
 1. load and run calibration example  
    it shows a header containing 6 numbers and 10 lines of 8 numbers
 1. wait until the middle 6 of the longer lines stabilize (should all be 0)
@@ -90,6 +108,15 @@ Note call **Wire.begin()** before **begin()**.
 - **bool wakeUp()** idem.
 
 
+### Calibrate
+
+- **void calibrate(uint16_t times)** This function overwrites the values of axe aye aze gxe gye gze.
+To get quality error numbers, the GY521 sensor should not move during calibration.
+The parameter times determines the number of measurements made.
+Typical values are 100 or more.  
+Please note this is a time consuming function.
+
+
 ### Throttle
 
 - **void setThrottle(bool throttle = true)** throttle to force "delay" between reads.
@@ -146,6 +173,12 @@ One must explicitly call **read()** to get new values.
 - **float getGyroX()** idem.
 - **float getGyroY()** idem.
 - **float getGyroZ()** idem.
+
+
+#### Experimental Pitch Roll and Yaw
+
+Pitch Roll and Yaw is work in progress and should not be used for projects yet.
+
 - **float getPitch()** idem. May return any number.
 If **setNormalize(true)** return value will be 0-359.999
 - **float getRoll()** idem. May return any number.
@@ -162,7 +195,7 @@ Read the register PDF for the specific value and meaning of registers.
 - **uint8_t getRegister(uint8_t reg)**
 
 
-## documents
+## Documents
 
 - check details registers - MPU-6000-Register-Map1.pdf
 
@@ -204,22 +237,27 @@ unit dps = degrees per second.
 
 ## Operation
 
-See examples, use with care 
+See examples, use with care.
 
 
 ## Future
 
 #### Must
 
+- time
 - improve documentation
+- investigate Pitch Roll and Yaw math in detail.
+  - investigate math needed.
+  - implementation.
+  - when?
 - test test and test ...(ESP too)
 
 #### Should
 
+- test **calibrate()** function for different sensitivities.
 
 #### Could
 
-- calibrate sketch could print code snippet to include...
 - add examples
 - improve unit tests?
 - reorder code in read(), would that save some micros.?
@@ -228,7 +266,6 @@ See examples, use with care
 - make enum for sensitivity Accel?
 - make enum for sensitivity Gyro?
 
-
 #### Wont
 
 - look for maths optimizations  (atan, hypot, performance)

examples/GY521_performance_calibrate/GY521_performance_calibrate.ino

@@ -0,0 +1,77 @@
+//
+//    FILE: GY521_performance_calibrate.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: read angleX, angleY, angleZ
+//     URL: https://github.com/RobTillaart/GY521
+
+
+#include "GY521.h"
+
+GY521 sensor(0x68);
+
+
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println();
+  Serial.println(__FILE__);
+  Serial.print("GY521_LIB_VERSION: ");
+  Serial.println(GY521_LIB_VERSION);
+
+  Wire.begin();
+
+  delay(100);
+  // while (sensor.wakeup() == false)
+  {
+    Serial.print(millis());
+    Serial.println("\tCould not connect to GY521: please check the GY521 address (0x68/0x69)");
+    delay(1000);
+  }
+  sensor.setAccelSensitivity(0);  //  2g
+  sensor.setGyroSensitivity(0);   //  250 degrees/s
+  sensor.setThrottle(false);
+
+  test(100);
+}
+
+
+void loop()
+{
+  Serial.println("\n\tTIME\tACCELEROMETER\t\tGYROSCOPE");
+  for (uint16_t times = 20; times <= 500; times += 20)
+  {
+    test(times);
+  }
+}
+
+
+
+void test(uint16_t times)
+{
+  //  flush all output
+  delay(100);
+  uint32_t start = micros();
+  sensor.calibrate(100);
+  uint32_t duration = micros() - start;
+
+  //  print results
+  Serial.print(times);
+  Serial.print('\t');
+  Serial.print(duration);
+  Serial.print('\t');
+  Serial.print(sensor.axe, 3);
+  Serial.print('\t');
+  Serial.print(sensor.aye, 3);
+  Serial.print('\t');
+  Serial.print(sensor.aze, 3);
+  Serial.print('\t');
+  Serial.print(sensor.gxe, 3);
+  Serial.print('\t');
+  Serial.print(sensor.gye, 3);
+  Serial.print('\t');
+  Serial.print(sensor.gze, 3);
+  Serial.print('\n');
+}
+
+
+//  -- END OF FILE --

examples/GY521_pitch_roll_yaw/GY521_pitch_roll_yaw.ino

@@ -19,6 +19,7 @@ void setup()
   Serial.println(__FILE__);
   Serial.print("GY521_LIB_VERSION: ");
   Serial.println(GY521_LIB_VERSION);
+  Serial.println("warning: Pitch roll yaw is work in progress.");
 
   Wire.begin();
 
@@ -29,19 +30,24 @@ void setup()
     Serial.println("\tCould not connect to GY521: please check the GY521 address (0x68/0x69)");
     delay(1000);
   }
+
   sensor.setAccelSensitivity(2);  //  8g
   sensor.setGyroSensitivity(1);   //  500 degrees/s
-
   sensor.setThrottle();
   Serial.println("start...");
 
+  // uint32_t startCalibrate = micros();
+  sensor.calibrate(100);
+  //  Serial.print("Duration: ");
+  //  Serial.println(micros() - startCalibrate);
+
   //  set calibration values from calibration sketch.
-  sensor.axe = 0.574;
-  sensor.aye = -0.002;
-  sensor.aze = -1.043;
-  sensor.gxe = 10.702;
-  sensor.gye = -6.436;
-  sensor.gze = -0.676;
+  //  sensor.axe = 0.574;
+  //  sensor.aye = -0.002;
+  //  sensor.aze = -1.043;
+  //  sensor.gxe = 10.702;
+  //  sensor.gye = -6.436;
+  //  sensor.gze = -0.676;
 }