Add readAccell(), readGyro and readTemperature() (#35)

* add readAccel() readGyro() readTemperature()
* update readme.md
* rename examples

GY521.cpp

@@ -1,7 +1,7 @@
 //
 //    FILE: GY521.cpp
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.3.6
+// VERSION: 0.3.7
 // PURPOSE: Arduino library for I2C GY521 accelerometer-gyroscope sensor
 //     URL: https://github.com/RobTillaart/GY521
 //
@@ -12,18 +12,23 @@
 //  0.1.3   2020-08-07  fix ESP support + pitch roll yaw demo
 //  0.1.4   2020-09-29  fix #5 missing ;
 //  0.1.5   2020-09-29  fix #6 fix maths for Teensy
+//
 //  0.2.0   2020-11-03  improve error handling
 //  0.2.1   2020-12-24  Arduino-CI + unit tests
 //  0.2.2   2021-01-24  add interface part to readme.md
 //                      add GY521_registers.h
 //  0.2.3   2021-01-26  align version numbers (oops)
+//
 //  0.3.0   2021-04-07  fix #18 acceleration error correction (kudo's to Merkxic)
 //  0.3.1   2021-06-13  added more unit test + some initialization
 //  0.3.2   2021-07-05  fix #20 support multiWire
 //  0.3.3   2021-07-05  fix #22 improve maths
 //  0.3.4   2021-07-12  fix #24 improve precision
 //  0.3.5   2021-10-20  update build-CI, badges + #28 add wakeup to begin().
 //  0.3.6   2021-12-18  update library.json, license, minor edits
+//  0.3.7   2022-07-26  add partial reads readAccel(),
+//                      readGyro() and readTemperature()
+//                      rename + add GY521_LIB_VERSION to examples.
 
 
 #include "GY521.h"
@@ -198,6 +203,152 @@ int16_t GY521::read()
 }
 
 
+int16_t GY521::readAccel()
+{
+  uint32_t now = millis();
+  if (_throttle)
+  {
+    if ((now - _lastTime) < _throttleTime)
+    {
+      // not an error.
+      return GY521_THROTTLED;
+    }
+  }
+  _lastTime = now;
+
+  // Connected ?
+  _wire->beginTransmission(_address);
+  _wire->write(GY521_ACCEL_XOUT_H);
+  if (_wire->endTransmission() != 0)
+  {
+    _error = GY521_ERROR_WRITE;
+    return _error;
+  }
+
+  // Get the data
+  int8_t n = _wire->requestFrom(_address, (uint8_t)6);
+  if (n != 6)
+  {
+    _error = GY521_ERROR_READ;
+    return _error;
+  }
+  // ACCELEROMETER
+  _ax = _WireRead2();  // ACCEL_XOUT_H  ACCEL_XOUT_L
+  _ay = _WireRead2();  // ACCEL_YOUT_H  ACCEL_YOUT_L
+  _az = _WireRead2();  // ACCEL_ZOUT_H  ACCEL_ZOUT_L
+
+  // next lines might be merged per axis.
+
+  // Convert raw acceleration to g's
+  _ax *= _raw2g;
+  _ay *= _raw2g;
+  _az *= _raw2g;
+
+  // Error correct raw acceleration (in g) measurements  // #18 kudos to Merkxic
+  _ax += axe;
+  _ay += aye;
+  _az += aze;
+
+  // prepare for Pitch Roll Yaw
+  float _ax2 = _ax * _ax;
+  float _ay2 = _ay * _ay;
+  float _az2 = _az * _az;
+
+  _aax = atan(       _ay / sqrt(_ax2 + _az2)) * RAD2DEGREES;
+  _aay = atan(-1.0 * _ax / sqrt(_ay2 + _az2)) * RAD2DEGREES;
+  _aaz = atan(       _az / sqrt(_ax2 + _ay2)) * RAD2DEGREES;
+  // optimize #22
+  // _aax = atan(_ay / hypot(_ax, _az)) * RAD2DEGREES;
+  // _aay = atan(-1.0 * _ax / hypot(_ay, _az)) * RAD2DEGREES;
+  // _aaz = atan(_az / hypot(_ax, _ay)) * RAD2DEGREES;
+
+  return GY521_OK;
+}
+
+
+int16_t GY521::readGyro()
+{
+  uint32_t now = millis();
+  if (_throttle)
+  {
+    if ((now - _lastTime) < _throttleTime)
+    {
+      // not an error.
+      return GY521_THROTTLED;
+    }
+  }
+  _lastTime = now;
+
+  // Connected ?
+  _wire->beginTransmission(_address);
+  _wire->write(GY521_GYRO_XOUT_H);
+  if (_wire->endTransmission() != 0)
+  {
+    _error = GY521_ERROR_WRITE;
+    return _error;
+  }
+
+  // Get the data
+  int8_t n = _wire->requestFrom(_address, (uint8_t)6);
+  if (n != 6)
+  {
+    _error = GY521_ERROR_READ;
+    return _error;
+  }
+  // GYROSCOPE
+  _gx = _WireRead2();  // GYRO_XOUT_H   GYRO_XOUT_L
+  _gy = _WireRead2();  // GYRO_YOUT_H   GYRO_YOUT_L
+  _gz = _WireRead2();  // GYRO_ZOUT_H   GYRO_ZOUT_L
+
+  // duration interval
+  now = micros();
+  float duration = (now - _lastMicros) * 1e-6;  // duration in seconds.
+  _lastMicros = now;
+
+  // next lines might be merged per axis.
+
+  // Convert raw Gyro to degrees/seconds
+  _gx *= _raw2dps;
+  _gy *= _raw2dps;
+  _gz *= _raw2dps;
+
+  // Error correct raw gyro measurements.
+  _gx += gxe;
+  _gy += gye;
+  _gz += gze;
+
+  _gax += _gx * duration;
+  _gay += _gy * duration;
+  _gaz += _gz * duration;
+
+  return GY521_OK;
+}
+
+
+int16_t GY521::readTemperature()
+{
+  //  DO NOT THROTTLE
+  _wire->beginTransmission(_address);
+  _wire->write(GY521_TEMP_OUT_H);
+  if (_wire->endTransmission() != 0)
+  {
+    _error = GY521_ERROR_WRITE;
+    return _error;
+  }
+
+  // Get the data
+  int8_t n = _wire->requestFrom(_address, (uint8_t)2);
+  if (n != 2)
+  {
+    _error = GY521_ERROR_READ;
+    return _error;
+  }
+  // TEMPERATURE
+  _temperature = _WireRead2(); // TEMP_OUT_H    TEMP_OUT_L
+  return GY521_OK;
+}
+
+
 bool GY521::setAccelSensitivity(uint8_t as)
 {
   _afs = as;

GY521.h

@@ -2,7 +2,7 @@
 //
 //    FILE: GY521.h
 //  AUTHOR: Rob Tillaart
-// VERSION: 0.3.6
+// VERSION: 0.3.7
 // PURPOSE: Arduino library for I2C GY521 accelerometer-gyroscope sensor
 //     URL: https://github.com/RobTillaart/GY521
 //
@@ -15,15 +15,15 @@
 #include "Wire.h"
 
 
-#define GY521_LIB_VERSION           (F("0.3.6"))
+#define GY521_LIB_VERSION           (F("0.3.7"))
 
 
 #ifndef GY521_THROTTLE_TIME
 #define GY521_THROTTLE_TIME         10   // milliseconds
 #endif
 
 
-// ERROR CODES
+//  ERROR CODES
 #define GY521_OK                     0
 #define GY521_THROTTLED              1
 #define GY521_ERROR_READ            -1
@@ -46,26 +46,35 @@ class GY521
 
 
   bool     wakeup();
-  // throttle to force delay between reads.
+  //  throttle to force delay between reads.
   void     setThrottle(bool throttle = true) { _throttle = throttle; };
   bool     getThrottle()                     { return _throttle; };
-  // 0..65535 (max milliseconds == roughly 1 minute.
+  //  0..65535 (max milliseconds == roughly 1 minute.
   void     setThrottleTime(uint16_t ti )     { _throttleTime = ti; };
   uint16_t getThrottleTime()                 { return _throttleTime; };
 
 
-  // returns GY521_OK or one of the error codes above.
+  //  READ THE SENSOR
+  //  returns GY521_OK or one of the error codes above.
   int16_t  read();
-
-  // SET BEFORE READ
-  // as = 0,1,2,3 ==> 2g 4g 8g 16g
+  //  optimized partial reading
+  //  read accelerometer only
+  int16_t readAccel();
+  //  read gyroscope only can be done too
+  //  however for pitch roll yaw you need all.
+  int16_t readGyro();
+  //  read temperature only, does not affect throttle.
+  int16_t readTemperature();
+
+  //  SET BEFORE READ
+  //  as = 0,1,2,3 ==> 2g 4g 8g 16g
   bool     setAccelSensitivity(uint8_t as);
   uint8_t  getAccelSensitivity();          // returns 0,1,2,3
-  // gs = 0,1,2,3  ==>  250, 500, 1000, 2000 degrees/second
+  //  gs = 0,1,2,3  ==>  250, 500, 1000, 2000 degrees/second
   bool     setGyroSensitivity(uint8_t gs);
   uint8_t  getGyroSensitivity();           // returns 0,1,2,3
 
-  // CALL AFTER READ
+  //  CALL AFTER READ
   float    getAccelX()   { return _ax; };
   float    getAccelY()   { return _ay; };
   float    getAccelZ()   { return _az; };
@@ -81,20 +90,20 @@ class GY521
   float    getYaw()      { return _yaw; };
 
 
-  // last time sensor is actually read.
+  //  last time sensor is actually read.
   uint32_t lastTime()    { return _lastTime; };
 
 
-  // generic worker to get access to all functionality
+  //  generic worker to get access to all functionality
   uint8_t  setRegister(uint8_t reg, uint8_t value);
   uint8_t  getRegister(uint8_t reg);
 
 
-  // get last error and reset error to OK.
+  //  get last error and reset error to OK.
   int16_t  getError()    { return _error; _error = GY521_OK; };
 
 
-  // calibration errors
+  //  calibration errors
   float    axe = 0, aye = 0, aze = 0;  // accelerometer errors
   float    gxe = 0, gye = 0, gze = 0;  // gyro errors
 

README.md

@@ -87,13 +87,20 @@ AD0 connected to VCC => 0x69
 - **bool setAccelSensitivity(uint8_t as)** as = 0, 1, 2, 3 ==> 2g 4g 8g 16g
 - **uint8_t getAccelSensitivity()** returns 0, 1, 2, 3
 - **bool setGyroSensitivity(uint8_t gs)** gs = 0,1,2,3  ==>  250, 500, 1000, 2000 degrees/second
-- **uint8_t  getGyroSensitivity()** returns 0, 1, 2, 3  
+- **uint8_t getGyroSensitivity()** returns 0, 1, 2, 3  
 
 
 #### Actual read
 
-- **int16_t read()** returns ...
-- **uint32_t lastTime()** last time sensor is actually read. In milliseconds.
+- **int16_t read()** returns status = GY521_OK on success.
+- **int16_t readAccel()** read accelerometer only to speed up interaction. This call does update the throttle timer.
+returns status = GY521_OK on success.
+- **int16_t readGyro()** read gyroscope only to speed up interaction. This call does update the throttle timer.
+returns status = GY521_OK on success.
+Note: for pitch roll yaw you need to call **read()**.
+- **int16_t readTemperature()** read temperature only, does **not** update the throttle timer.
+returns status = GY521_OK on success.
+- **uint32_t lastTime()** last time sensor is actually read. In milliseconds. Not updated by readTemperature().
 
 
 #### Call after read
@@ -144,5 +151,4 @@ See examples, use with care
 **Could**
 - calibrate function in the lib ?  (think not as lib might grow?)
 - calibrate sketch could print code snippet to include...
-- option to read only Accel?
-- option to read only Gyro?
+

examples/GY521_angle/GY521_angle.ino

@@ -0,0 +1,74 @@
+//
+//    FILE: GY521_angle.ino
+//  AUTHOR: Rob Tillaart
+// PURPOSE: demo pitch roll yaw
+//    DATE: 2022-06-06
+
+
+#include "GY521.h"
+
+GY521 sensor(0x68);
+
+uint32_t counter = 0;
+
+
+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");
+    delay(1000);
+  }
+  sensor.setAccelSensitivity(2);  // 8g
+  sensor.setGyroSensitivity(1);   // 500 degrees/s
+
+  sensor.setThrottle();
+  Serial.println("start...");
+
+  // 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;
+}
+
+
+void loop()
+{
+  sensor.read();
+  float x = sensor.getAngleX();
+  float y = sensor.getAngleY();
+  float z = sensor.getAngleZ();
+
+  if (counter % 10 == 0)
+  {
+    // Serial.println("\nCNT\tX\tY\tZ");
+  }
+
+  //Serial.print(counter);
+  //Serial.print('\t');
+  Serial.print(x, 1);
+  Serial.print('\t');
+  Serial.print(y, 1);
+  Serial.print('\t');
+  Serial.print(z, 1);
+  Serial.println();
+
+  counter++;
+}
+
+
+// -- END OF FILE --
+

examples/GY521_performance/GY521_performance.ino

@@ -16,7 +16,10 @@ uint32_t counter = 0;
 void setup()
 {
   Serial.begin(115200);
+  Serial.println();
   Serial.println(__FILE__);
+  Serial.print("GY521_LIB_VERSION: ");
+  Serial.println(GY521_LIB_VERSION);
 
   Wire.begin();