Yuxiang Yang
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MPU6050IMU
by 
Austin Buchan
Revision 4:095b126178df, committed 2017-05-30
- Comitter:
- yxyang
- Date:
- Tue May 30 06:42:08 2017 +0000
- Parent:
- 3:359efdec694f
- Commit message:
Changed in this revision
| MPU6050.h | Show annotated file Show diff for this revision Revisions of this file |
diff -r 359efdec694f -r 095b126178df MPU6050.h
--- a/MPU6050.h Mon Oct 05 19:34:26 2015 +0000
+++ b/MPU6050.h Tue May 30 06:42:08 2017 +0000
@@ -1,84 +1,93 @@
#ifndef MPU6050_H
#define MPU6050_H
-
-#include "mbed.h"
+
#include "math.h"
-
- // Define registers per MPU6050, Register Map and Descriptions, Rev 4.2, 08/19/2013 6 DOF Motion sensor fusion device
+#include "mbed.h"
+
+// Define registers per MPU6050, Register Map and Descriptions, Rev 4.2,
+// 08/19/2013 6 DOF Motion sensor fusion device
// Invensense Inc., www.invensense.com
-// See also MPU-6050 Register Map and Descriptions, Revision 4.0, RM-MPU-6050A-00, 9/12/2012 for registers not listed in
-// above document; the MPU6050 and MPU 9150 are virtually identical but the latter has an on-board magnetic sensor
+// See also MPU-6050 Register Map and Descriptions, Revision 4.0,
+// RM-MPU-6050A-00, 9/12/2012 for registers not listed in
+// above document; the MPU6050 and MPU 9150 are virtually identical but the
+// latter has an on-board magnetic sensor
//
-#define XGOFFS_TC 0x00 // Bit 7 PWR_MODE, bits 6:1 XG_OFFS_TC, bit 0 OTP_BNK_VLD
-#define YGOFFS_TC 0x01
-#define ZGOFFS_TC 0x02
-#define X_FINE_GAIN 0x03 // [7:0] fine gain
-#define Y_FINE_GAIN 0x04
-#define Z_FINE_GAIN 0x05
-#define XA_OFFSET_H 0x06 // User-defined trim values for accelerometer
-#define XA_OFFSET_L_TC 0x07
-#define YA_OFFSET_H 0x08
-#define YA_OFFSET_L_TC 0x09
-#define ZA_OFFSET_H 0x0A
-#define ZA_OFFSET_L_TC 0x0B
-#define SELF_TEST_X 0x0D
-#define SELF_TEST_Y 0x0E
-#define SELF_TEST_Z 0x0F
-#define SELF_TEST_A 0x10
-#define XG_OFFS_USRH 0x13 // User-defined trim values for gyroscope; supported in MPU-6050?
-#define XG_OFFS_USRL 0x14
-#define YG_OFFS_USRH 0x15
-#define YG_OFFS_USRL 0x16
-#define ZG_OFFS_USRH 0x17
-#define ZG_OFFS_USRL 0x18
-#define SMPLRT_DIV 0x19
-#define CONFIG 0x1A
-#define GYRO_CONFIG 0x1B
-#define ACCEL_CONFIG 0x1C
-#define FF_THR 0x1D // Free-fall
-#define FF_DUR 0x1E // Free-fall
-#define MOT_THR 0x1F // Motion detection threshold bits [7:0]
-#define MOT_DUR 0x20 // Duration counter threshold for motion interrupt generation, 1 kHz rate, LSB = 1 ms
-#define ZMOT_THR 0x21 // Zero-motion detection threshold bits [7:0]
-#define ZRMOT_DUR 0x22 // Duration counter threshold for zero motion interrupt generation, 16 Hz rate, LSB = 64 ms
-#define FIFO_EN 0x23
-#define I2C_MST_CTRL 0x24
-#define I2C_SLV0_ADDR 0x25
-#define I2C_SLV0_REG 0x26
-#define I2C_SLV0_CTRL 0x27
-#define I2C_SLV1_ADDR 0x28
-#define I2C_SLV1_REG 0x29
-#define I2C_SLV1_CTRL 0x2A
-#define I2C_SLV2_ADDR 0x2B
-#define I2C_SLV2_REG 0x2C
-#define I2C_SLV2_CTRL 0x2D
-#define I2C_SLV3_ADDR 0x2E
-#define I2C_SLV3_REG 0x2F
-#define I2C_SLV3_CTRL 0x30
-#define I2C_SLV4_ADDR 0x31
-#define I2C_SLV4_REG 0x32
-#define I2C_SLV4_DO 0x33
-#define I2C_SLV4_CTRL 0x34
-#define I2C_SLV4_DI 0x35
-#define I2C_MST_STATUS 0x36
-#define INT_PIN_CFG 0x37
-#define INT_ENABLE 0x38
-#define DMP_INT_STATUS 0x39 // Check DMP interrupt
-#define INT_STATUS 0x3A
-#define ACCEL_XOUT_H 0x3B
-#define ACCEL_XOUT_L 0x3C
-#define ACCEL_YOUT_H 0x3D
-#define ACCEL_YOUT_L 0x3E
-#define ACCEL_ZOUT_H 0x3F
-#define ACCEL_ZOUT_L 0x40
-#define TEMP_OUT_H 0x41
-#define TEMP_OUT_L 0x42
-#define GYRO_XOUT_H 0x43
-#define GYRO_XOUT_L 0x44
-#define GYRO_YOUT_H 0x45
-#define GYRO_YOUT_L 0x46
-#define GYRO_ZOUT_H 0x47
-#define GYRO_ZOUT_L 0x48
+#define XGOFFS_TC \
+ 0x00 // Bit 7 PWR_MODE, bits 6:1 XG_OFFS_TC, bit 0 OTP_BNK_VLD
+#define YGOFFS_TC 0x01
+#define ZGOFFS_TC 0x02
+#define X_FINE_GAIN 0x03 // [7:0] fine gain
+#define Y_FINE_GAIN 0x04
+#define Z_FINE_GAIN 0x05
+#define XA_OFFSET_H 0x06 // User-defined trim values for accelerometer
+#define XA_OFFSET_L_TC 0x07
+#define YA_OFFSET_H 0x08
+#define YA_OFFSET_L_TC 0x09
+#define ZA_OFFSET_H 0x0A
+#define ZA_OFFSET_L_TC 0x0B
+#define SELF_TEST_X 0x0D
+#define SELF_TEST_Y 0x0E
+#define SELF_TEST_Z 0x0F
+#define SELF_TEST_A 0x10
+#define XG_OFFS_USRH \
+ 0x13 // User-defined trim values for gyroscope; supported in MPU-6050?
+#define XG_OFFS_USRL 0x14
+#define YG_OFFS_USRH 0x15
+#define YG_OFFS_USRL 0x16
+#define ZG_OFFS_USRH 0x17
+#define ZG_OFFS_USRL 0x18
+#define SMPLRT_DIV 0x19
+#define CONFIG 0x1A
+#define GYRO_CONFIG 0x1B
+#define ACCEL_CONFIG 0x1C
+#define FF_THR 0x1D // Free-fall
+#define FF_DUR 0x1E // Free-fall
+#define MOT_THR 0x1F // Motion detection threshold bits [7:0]
+#define MOT_DUR \
+ 0x20 // Duration counter threshold for motion interrupt generation, 1 kHz
+ // rate, LSB = 1 ms
+#define ZMOT_THR 0x21 // Zero-motion detection threshold bits [7:0]
+#define ZRMOT_DUR \
+ 0x22 // Duration counter threshold for zero motion interrupt generation, 16
+ // Hz rate, LSB = 64 ms
+#define FIFO_EN 0x23
+#define I2C_MST_CTRL 0x24
+#define I2C_SLV0_ADDR 0x25
+#define I2C_SLV0_REG 0x26
+#define I2C_SLV0_CTRL 0x27
+#define I2C_SLV1_ADDR 0x28
+#define I2C_SLV1_REG 0x29
+#define I2C_SLV1_CTRL 0x2A
+#define I2C_SLV2_ADDR 0x2B
+#define I2C_SLV2_REG 0x2C
+#define I2C_SLV2_CTRL 0x2D
+#define I2C_SLV3_ADDR 0x2E
+#define I2C_SLV3_REG 0x2F
+#define I2C_SLV3_CTRL 0x30
+#define I2C_SLV4_ADDR 0x31
+#define I2C_SLV4_REG 0x32
+#define I2C_SLV4_DO 0x33
+#define I2C_SLV4_CTRL 0x34
+#define I2C_SLV4_DI 0x35
+#define I2C_MST_STATUS 0x36
+#define INT_PIN_CFG 0x37
+#define INT_ENABLE 0x38
+#define DMP_INT_STATUS 0x39 // Check DMP interrupt
+#define INT_STATUS 0x3A
+#define ACCEL_XOUT_H 0x3B
+#define ACCEL_XOUT_L 0x3C
+#define ACCEL_YOUT_H 0x3D
+#define ACCEL_YOUT_L 0x3E
+#define ACCEL_ZOUT_H 0x3F
+#define ACCEL_ZOUT_L 0x40
+#define TEMP_OUT_H 0x41
+#define TEMP_OUT_L 0x42
+#define GYRO_XOUT_H 0x43
+#define GYRO_XOUT_L 0x44
+#define GYRO_YOUT_H 0x45
+#define GYRO_YOUT_L 0x46
+#define GYRO_ZOUT_H 0x47
+#define GYRO_ZOUT_L 0x48
#define EXT_SENS_DATA_00 0x49
#define EXT_SENS_DATA_01 0x4A
#define EXT_SENS_DATA_02 0x4B
@@ -104,44 +113,49 @@
#define EXT_SENS_DATA_22 0x5F
#define EXT_SENS_DATA_23 0x60
#define MOT_DETECT_STATUS 0x61
-#define I2C_SLV0_DO 0x63
-#define I2C_SLV1_DO 0x64
-#define I2C_SLV2_DO 0x65
-#define I2C_SLV3_DO 0x66
+#define I2C_SLV0_DO 0x63
+#define I2C_SLV1_DO 0x64
+#define I2C_SLV2_DO 0x65
+#define I2C_SLV3_DO 0x66
#define I2C_MST_DELAY_CTRL 0x67
-#define SIGNAL_PATH_RESET 0x68
-#define MOT_DETECT_CTRL 0x69
-#define USER_CTRL 0x6A // Bit 7 enable DMP, bit 3 reset DMP
-#define PWR_MGMT_1 0x6B // Device defaults to the SLEEP mode
-#define PWR_MGMT_2 0x6C
-#define DMP_BANK 0x6D // Activates a specific bank in the DMP
-#define DMP_RW_PNT 0x6E // Set read/write pointer to a specific start address in specified DMP bank
-#define DMP_REG 0x6F // Register in DMP from which to read or to which to write
-#define DMP_REG_1 0x70
-#define DMP_REG_2 0x71
-#define FIFO_COUNTH 0x72
-#define FIFO_COUNTL 0x73
-#define FIFO_R_W 0x74
+#define SIGNAL_PATH_RESET 0x68
+#define MOT_DETECT_CTRL 0x69
+#define USER_CTRL 0x6A // Bit 7 enable DMP, bit 3 reset DMP
+#define PWR_MGMT_1 0x6B // Device defaults to the SLEEP mode
+#define PWR_MGMT_2 0x6C
+#define DMP_BANK 0x6D // Activates a specific bank in the DMP
+#define DMP_RW_PNT \
+ 0x6E // Set read/write pointer to a specific start address in specified DMP
+ // bank
+#define DMP_REG 0x6F // Register in DMP from which to read or to which to write
+#define DMP_REG_1 0x70
+#define DMP_REG_2 0x71
+#define FIFO_COUNTH 0x72
+#define FIFO_COUNTL 0x73
+#define FIFO_R_W 0x74
#define WHO_AM_I_MPU6050 0x75 // Should return 0x68
-// Using the GY-521 breakout board, I set ADO to 0 by grounding through a 4k7 resistor
+// Using the GY-521 breakout board, I set ADO to 0 by grounding through a 4k7
+// resistor
// Seven-bit device address is 110100 for ADO = 0 and 110101 for ADO = 1
#define ADO 0
#if ADO
-#define MPU6050_ADDRESS 0x69<<1 // Device address when ADO = 1
+#define MPU6050_ADDRESS 0x69 << 1 // Device address when ADO = 1
#else
-#define MPU6050_ADDRESS 0x68<<1 // Device address when ADO = 0
+#define MPU6050_ADDRESS 0x68 << 1 // Device address when ADO = 0
#endif
// Set initial input parameters
-enum Ascale {
+enum Ascale
+{
AFS_2G = 0,
AFS_4G,
AFS_8G,
AFS_16G
};
-enum Gscale {
+enum Gscale
+{
GFS_250DPS = 0,
GFS_500DPS,
GFS_1000DPS,
@@ -152,24 +166,27 @@
int Gscale = GFS_250DPS;
int Ascale = AFS_2G;
-//Set up I2C, (SDA,SCL)
+// Set up I2C, (SDA,SCL)
#define MPU_SDA p9
#define MPU_SCL p10
-I2C i2c(MPU_SDA, MPU_SCL);
+I2C i2c (MPU_SDA, MPU_SCL);
-//DigitalOut myled(LED1);
-
+// DigitalOut myled(LED1);
+
float aRes, gRes; // scale resolutions per LSB for the sensors
-
+
// Pin definitions
-int intPin = 12; // These can be changed, 2 and 3 are the Arduinos ext int pins
+int intPin = 12; // These can be changed, 2 and 3 are the Arduinos ext int pins
-int16_t accelCount[3]; // Stores the 16-bit signed accelerometer sensor output
-float ax, ay, az; // Stores the real accel value in g's
-int16_t gyroCount[3]; // Stores the 16-bit signed gyro sensor output
-float gx, gy, gz; // Stores the real gyro value in degrees per seconds
-float gyroBias[3] = {0, 0, 0}, accelBias[3] = {0, 0, 0}; // Bias corrections for gyro and accelerometer
-int16_t tempCount; // Stores the real internal chip temperature in degrees Celsius
+int16_t accelCount[3]; // Stores the 16-bit signed accelerometer sensor output
+float ax, ay, az; // Stores the real accel value in g's
+int16_t gyroCount[3]; // Stores the 16-bit signed gyro sensor output
+float gx, gy, gz; // Stores the real gyro value in degrees per seconds
+float gyroBias[3] = { 0, 0, 0 },
+ accelBias[3]
+ = { 0, 0, 0 }; // Bias corrections for gyro and accelerometer
+int16_t
+ tempCount; // Stores the real internal chip temperature in degrees Celsius
float temperature;
float SelfTest[6];
@@ -178,511 +195,713 @@
// parameters for 6 DoF sensor fusion calculations
float PI = 3.14159265358979323846f;
-float GyroMeasError = PI * (60.0f / 180.0f); // gyroscope measurement error in rads/s (start at 60 deg/s), then reduce after ~10 s to 3
-float beta = sqrt(3.0f / 4.0f) * GyroMeasError; // compute beta
-float GyroMeasDrift = PI * (1.0f / 180.0f); // gyroscope measurement drift in rad/s/s (start at 0.0 deg/s/s)
-float zeta = sqrt(3.0f / 4.0f) * GyroMeasDrift; // compute zeta, the other free parameter in the Madgwick scheme usually set to a small or zero value
+float GyroMeasError = PI * (60.0f / 180.0f); // gyroscope measurement error in
+ // rads/s (start at 60 deg/s),
+ // then reduce after ~10 s to 3
+float beta = sqrt (3.0f / 4.0f) * GyroMeasError; // compute beta
+float GyroMeasDrift = PI * (1.0f / 180.0f); // gyroscope measurement drift in
+ // rad/s/s (start at 0.0 deg/s/s)
+float zeta = sqrt (3.0f / 4.0f) * GyroMeasDrift; // compute zeta, the other
+ // free parameter in the
+ // Madgwick scheme usually set
+ // to a small or zero value
float pitch, yaw, roll;
-float deltat = 0.0f; // integration interval for both filter schemes
-int lastUpdate = 0, firstUpdate = 0, Now = 0; // used to calculate integration interval // used to calculate integration interval
-float q[4] = {1.0f, 0.0f, 0.0f, 0.0f}; // vector to hold quaternion
+float deltat = 0.0f; // integration interval for both filter schemes
+int lastUpdate = 0, firstUpdate = 0,
+ Now = 0; // used to calculate integration interval
+ // // used to calculate integration interval
+float q[4] = { 1.0f, 0.0f, 0.0f, 0.0f }; // vector to hold quaternion
-class MPU6050 {
-
- protected:
-
- public:
+class MPU6050
+{
+
+protected:
+public:
//===================================================================================================================
-//====== Set of useful function to access acceleratio, gyroscope, and temperature data
-//===================================================================================================================
+ //====== Set of useful function to access acceleratio, gyroscope, and
+ // temperature data
+ //===================================================================================================================
- void writeByte(uint8_t address, uint8_t subAddress, uint8_t data)
-{
- char data_write[2];
- data_write[0] = subAddress;
- data_write[1] = data;
- i2c.write(address, data_write, 2, 0);
-}
+ void
+ writeByte (uint8_t address, uint8_t subAddress, uint8_t data)
+ {
+ char data_write[2];
+ data_write[0] = subAddress;
+ data_write[1] = data;
+ i2c.write (address, data_write, 2, 0);
+ }
- char readByte(uint8_t address, uint8_t subAddress)
-{
- char data[1]; // `data` will store the register data
+ char
+ readByte (uint8_t address, uint8_t subAddress)
+ {
+ char data[1]; // `data` will store the register data
char data_write[1];
data_write[0] = subAddress;
- i2c.write(address, data_write, 1, 1); // no stop
- i2c.read(address, data, 1, 0);
- return data[0];
-}
+ i2c.write (address, data_write, 1, 1); // no stop
+ i2c.read (address, data, 1, 0);
+ return data[0];
+ }
- void readBytes(uint8_t address, uint8_t subAddress, uint8_t count, uint8_t * dest)
-{
+ void
+ readBytes (uint8_t address, uint8_t subAddress, uint8_t count, uint8_t *dest)
+ {
char data[14];
char data_write[1];
data_write[0] = subAddress;
- i2c.write(address, data_write, 1, 1); // no stop
- i2c.read(address, data, count, 0);
- for(int ii = 0; ii < count; ii++) {
- dest[ii] = data[ii];
- }
-}
-
+ i2c.write (address, data_write, 1, 1); // no stop
+ i2c.read (address, data, count, 0);
+ for (int ii = 0; ii < count; ii++)
+ {
+ dest[ii] = data[ii];
+ }
+ }
-void getGres() {
- switch (Gscale)
- {
- // Possible gyro scales (and their register bit settings) are:
- // 250 DPS (00), 500 DPS (01), 1000 DPS (10), and 2000 DPS (11).
- // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value:
- case GFS_250DPS:
- gRes = 250.0/32768.0;
- break;
- case GFS_500DPS:
- gRes = 500.0/32768.0;
- break;
- case GFS_1000DPS:
- gRes = 1000.0/32768.0;
- break;
- case GFS_2000DPS:
- gRes = 2000.0/32768.0;
- break;
- }
-}
-
-void getAres() {
- switch (Ascale)
+ void
+ getGres ()
{
- // Possible accelerometer scales (and their register bit settings) are:
- // 2 Gs (00), 4 Gs (01), 8 Gs (10), and 16 Gs (11).
- // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value:
- case AFS_2G:
- aRes = 2.0/32768.0;
- break;
- case AFS_4G:
- aRes = 4.0/32768.0;
- break;
- case AFS_8G:
- aRes = 8.0/32768.0;
- break;
- case AFS_16G:
- aRes = 16.0/32768.0;
- break;
+ switch (Gscale)
+ {
+ // Possible gyro scales (and their register bit settings) are:
+ // 250 DPS (00), 500 DPS (01), 1000 DPS (10), and 2000 DPS (11).
+ // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that
+ // 2-bit value:
+ case GFS_250DPS:
+ gRes = 250.0 / 32768.0;
+ break;
+ case GFS_500DPS:
+ gRes = 500.0 / 32768.0;
+ break;
+ case GFS_1000DPS:
+ gRes = 1000.0 / 32768.0;
+ break;
+ case GFS_2000DPS:
+ gRes = 2000.0 / 32768.0;
+ break;
+ }
}
-}
-
-void readAccelData(int16_t * destination)
-{
- uint8_t rawData[6]; // x/y/z accel register data stored here
- readBytes(MPU6050_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array
- destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
- destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
- destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
-}
-
-void readGyroData(int16_t * destination)
-{
- uint8_t rawData[6]; // x/y/z gyro register data stored here
- readBytes(MPU6050_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array
- destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
- destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
- destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
-}
+ void
+ getAres ()
+ {
+ switch (Ascale)
+ {
+ // Possible accelerometer scales (and their register bit settings) are:
+ // 2 Gs (00), 4 Gs (01), 8 Gs (10), and 16 Gs (11).
+ // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that
+ // 2-bit value:
+ case AFS_2G:
+ aRes = 2.0 / 32768.0;
+ break;
+ case AFS_4G:
+ aRes = 4.0 / 32768.0;
+ break;
+ case AFS_8G:
+ aRes = 8.0 / 32768.0;
+ break;
+ case AFS_16G:
+ aRes = 16.0 / 32768.0;
+ break;
+ }
+ }
-int16_t readTempData()
-{
- uint8_t rawData[2]; // x/y/z gyro register data stored here
- readBytes(MPU6050_ADDRESS, TEMP_OUT_H, 2, &rawData[0]); // Read the two raw data registers sequentially into data array
- return (int16_t)(((int16_t)rawData[0]) << 8 | rawData[1]) ; // Turn the MSB and LSB into a 16-bit value
-}
-
-
-
-// Configure the motion detection control for low power accelerometer mode
-void LowPowerAccelOnly()
-{
+ void
+ readAccelData (int16_t *destination)
+ {
+ uint8_t rawData[6]; // x/y/z accel register data stored here
+ readBytes (MPU6050_ADDRESS, ACCEL_XOUT_H, 6,
+ &rawData[0]); // Read the six raw data registers into data array
+ destination[0] = (int16_t) (
+ ((int16_t)rawData[0] << 8)
+ | rawData[1]); // Turn the MSB and LSB into a signed 16-bit value
+ destination[1] = (int16_t) (((int16_t)rawData[2] << 8) | rawData[3]);
+ destination[2] = (int16_t) (((int16_t)rawData[4] << 8) | rawData[5]);
+ }
-// The sensor has a high-pass filter necessary to invoke to allow the sensor motion detection algorithms work properly
-// Motion detection occurs on free-fall (acceleration below a threshold for some time for all axes), motion (acceleration
-// above a threshold for some time on at least one axis), and zero-motion toggle (acceleration on each axis less than a
-// threshold for some time sets this flag, motion above the threshold turns it off). The high-pass filter takes gravity out
-// consideration for these threshold evaluations; otherwise, the flags would be set all the time!
-
- uint8_t c = readByte(MPU6050_ADDRESS, PWR_MGMT_1);
- writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c & ~0x30); // Clear sleep and cycle bits [5:6]
- writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c | 0x30); // Set sleep and cycle bits [5:6] to zero to make sure accelerometer is running
-
- c = readByte(MPU6050_ADDRESS, PWR_MGMT_2);
- writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c & ~0x38); // Clear standby XA, YA, and ZA bits [3:5]
- writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c | 0x00); // Set XA, YA, and ZA bits [3:5] to zero to make sure accelerometer is running
-
- c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
- writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x07); // Clear high-pass filter bits [2:0]
-// Set high-pass filter to 0) reset (disable), 1) 5 Hz, 2) 2.5 Hz, 3) 1.25 Hz, 4) 0.63 Hz, or 7) Hold
- writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c | 0x00); // Set ACCEL_HPF to 0; reset mode disbaling high-pass filter
+ void
+ readGyroData (int16_t *destination)
+ {
+ uint8_t rawData[6]; // x/y/z gyro register data stored here
+ readBytes (MPU6050_ADDRESS, GYRO_XOUT_H, 6,
+ &rawData[0]); // Read the six raw data registers sequentially
+ // into data array
+ destination[0] = (int16_t) (
+ ((int16_t)rawData[0] << 8)
+ | rawData[1]); // Turn the MSB and LSB into a signed 16-bit value
+ destination[1] = (int16_t) (((int16_t)rawData[2] << 8) | rawData[3]);
+ destination[2] = (int16_t) (((int16_t)rawData[4] << 8) | rawData[5]);
+ }
- c = readByte(MPU6050_ADDRESS, CONFIG);
- writeByte(MPU6050_ADDRESS, CONFIG, c & ~0x07); // Clear low-pass filter bits [2:0]
- writeByte(MPU6050_ADDRESS, CONFIG, c | 0x00); // Set DLPD_CFG to 0; 260 Hz bandwidth, 1 kHz rate
-
- c = readByte(MPU6050_ADDRESS, INT_ENABLE);
- writeByte(MPU6050_ADDRESS, INT_ENABLE, c & ~0xFF); // Clear all interrupts
- writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x40); // Enable motion threshold (bits 5) interrupt only
-
-// Motion detection interrupt requires the absolute value of any axis to lie above the detection threshold
-// for at least the counter duration
- writeByte(MPU6050_ADDRESS, MOT_THR, 0x80); // Set motion detection to 0.256 g; LSB = 2 mg
- writeByte(MPU6050_ADDRESS, MOT_DUR, 0x01); // Set motion detect duration to 1 ms; LSB is 1 ms @ 1 kHz rate
-
- wait(0.1); // Add delay for accumulation of samples
-
- c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
- writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x07); // Clear high-pass filter bits [2:0]
- writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c | 0x07); // Set ACCEL_HPF to 7; hold the initial accleration value as a referance
-
- c = readByte(MPU6050_ADDRESS, PWR_MGMT_2);
- writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c & ~0xC7); // Clear standby XA, YA, and ZA bits [3:5] and LP_WAKE_CTRL bits [6:7]
- writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c | 0x47); // Set wakeup frequency to 5 Hz, and disable XG, YG, and ZG gyros (bits [0:2])
+ int16_t
+ readTempData ()
+ {
+ uint8_t rawData[2]; // x/y/z gyro register data stored here
+ readBytes (MPU6050_ADDRESS, TEMP_OUT_H, 2,
+ &rawData[0]); // Read the two raw data registers sequentially
+ // into data array
+ return (int16_t) (
+ ((int16_t)rawData[0]) << 8
+ | rawData[1]); // Turn the MSB and LSB into a 16-bit value
+ }
+
+ // Configure the motion detection control for low power accelerometer mode
+ void
+ LowPowerAccelOnly ()
+ {
- c = readByte(MPU6050_ADDRESS, PWR_MGMT_1);
- writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c & ~0x20); // Clear sleep and cycle bit 5
- writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c | 0x20); // Set cycle bit 5 to begin low power accelerometer motion interrupts
-
-}
-
+ // The sensor has a high-pass filter necessary to invoke to allow the
+ // sensor motion detection algorithms work properly
+ // Motion detection occurs on free-fall (acceleration below a threshold for
+ // some time for all axes), motion (acceleration
+ // above a threshold for some time on at least one axis), and zero-motion
+ // toggle (acceleration on each axis less than a
+ // threshold for some time sets this flag, motion above the threshold turns
+ // it off). The high-pass filter takes gravity out
+ // consideration for these threshold evaluations; otherwise, the flags
+ // would be set all the time!
-void resetMPU6050() {
- // reset device
- writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
- wait(0.1);
- }
-
-
-void initMPU6050()
-{
- // Initialize MPU6050 device
- // wake up device
- writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00); // Clear sleep mode bit (6), enable all sensors
- wait(0.1); // Delay 100 ms for PLL to get established on x-axis gyro; should check for PLL ready interrupt
+ uint8_t c = readByte (MPU6050_ADDRESS, PWR_MGMT_1);
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_1,
+ c & ~0x30); // Clear sleep and cycle bits [5:6]
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_1,
+ c | 0x30); // Set sleep and cycle bits [5:6] to zero to make
+ // sure accelerometer is running
- // get stable time source
- writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01); // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001
+ c = readByte (MPU6050_ADDRESS, PWR_MGMT_2);
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_2,
+ c & ~0x38); // Clear standby XA, YA, and ZA bits [3:5]
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_2,
+ c | 0x00); // Set XA, YA, and ZA bits [3:5] to zero to make sure
+ // accelerometer is running
- // Configure Gyro and Accelerometer
- // Disable FSYNC and set accelerometer and gyro bandwidth to 44 and 42 Hz, respectively;
- // DLPF_CFG = bits 2:0 = 010; this sets the sample rate at 1 kHz for both
- // Maximum delay is 4.9 ms which is just over a 200 Hz maximum rate
- writeByte(MPU6050_ADDRESS, CONFIG, 0x03);
-
- // Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV)
- writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x04); // Use a 200 Hz rate; the same rate set in CONFIG above
-
- // Set gyroscope full scale range
- // Range selects FS_SEL and AFS_SEL are 0 - 3, so 2-bit values are left-shifted into positions 4:3
- uint8_t c = readByte(MPU6050_ADDRESS, GYRO_CONFIG);
- writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c & ~0xE0); // Clear self-test bits [7:5]
- writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
- writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c | Gscale << 3); // Set full scale range for the gyro
-
- // Set accelerometer configuration
- c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
- writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0xE0); // Clear self-test bits [7:5]
- writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
- writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c | Ascale << 3); // Set full scale range for the accelerometer
+ c = readByte (MPU6050_ADDRESS, ACCEL_CONFIG);
+ writeByte (MPU6050_ADDRESS, ACCEL_CONFIG,
+ c & ~0x07); // Clear high-pass filter bits [2:0]
+ // Set high-pass filter to 0) reset (disable), 1) 5 Hz, 2) 2.5 Hz, 3) 1.25
+ // Hz, 4) 0.63 Hz, or 7) Hold
+ writeByte (
+ MPU6050_ADDRESS, ACCEL_CONFIG,
+ c | 0x00); // Set ACCEL_HPF to 0; reset mode disbaling high-pass filter
- // Configure Interrupts and Bypass Enable
- // Set interrupt pin active high, push-pull, and clear on read of INT_STATUS, enable I2C_BYPASS_EN so additional chips
- // can join the I2C bus and all can be controlled by the Arduino as master
- writeByte(MPU6050_ADDRESS, INT_PIN_CFG, 0x22);
- writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x01); // Enable data ready (bit 0) interrupt
-}
+ c = readByte (MPU6050_ADDRESS, CONFIG);
+ writeByte (MPU6050_ADDRESS, CONFIG,
+ c & ~0x07); // Clear low-pass filter bits [2:0]
+ writeByte (MPU6050_ADDRESS, CONFIG,
+ c | 0x00); // Set DLPD_CFG to 0; 260 Hz bandwidth, 1 kHz rate
+
+ c = readByte (MPU6050_ADDRESS, INT_ENABLE);
+ writeByte (MPU6050_ADDRESS, INT_ENABLE, c & ~0xFF); // Clear all interrupts
+ writeByte (MPU6050_ADDRESS, INT_ENABLE,
+ 0x40); // Enable motion threshold (bits 5) interrupt only
-// Function which accumulates gyro and accelerometer data after device initialization. It calculates the average
-// of the at-rest readings and then loads the resulting offsets into accelerometer and gyro bias registers.
-void calibrateMPU6050(float * dest1, float * dest2)
-{
- uint8_t data[12]; // data array to hold accelerometer and gyro x, y, z, data
- uint16_t ii, packet_count, fifo_count;
- int32_t gyro_bias[3] = {0, 0, 0}, accel_bias[3] = {0, 0, 0};
-
-// reset device, reset all registers, clear gyro and accelerometer bias registers
- writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
- wait(0.1);
-
-// get stable time source
-// Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001
- writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01);
- writeByte(MPU6050_ADDRESS, PWR_MGMT_2, 0x00);
- wait(0.2);
-
-// Configure device for bias calculation
- writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x00); // Disable all interrupts
- writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00); // Disable FIFO
- writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00); // Turn on internal clock source
- writeByte(MPU6050_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master
- writeByte(MPU6050_ADDRESS, USER_CTRL, 0x00); // Disable FIFO and I2C master modes
- writeByte(MPU6050_ADDRESS, USER_CTRL, 0x0C); // Reset FIFO and DMP
- wait(0.015);
-
-// Configure MPU6050 gyro and accelerometer for bias calculation
- writeByte(MPU6050_ADDRESS, CONFIG, 0x01); // Set low-pass filter to 188 Hz
- writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x00); // Set sample rate to 1 kHz
- writeByte(MPU6050_ADDRESS, GYRO_CONFIG, 0x00); // Set gyro full-scale to 250 degrees per second, maximum sensitivity
- writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity
-
- uint16_t gyrosensitivity = 131; // = 131 LSB/degrees/sec
- uint16_t accelsensitivity = 16384; // = 16384 LSB/g
+ // Motion detection interrupt requires the absolute value of any axis to
+ // lie above the detection threshold
+ // for at least the counter duration
+ writeByte (MPU6050_ADDRESS, MOT_THR,
+ 0x80); // Set motion detection to 0.256 g; LSB = 2 mg
+ writeByte (
+ MPU6050_ADDRESS, MOT_DUR,
+ 0x01); // Set motion detect duration to 1 ms; LSB is 1 ms @ 1 kHz rate
+
+ wait (0.1); // Add delay for accumulation of samples
-// Configure FIFO to capture accelerometer and gyro data for bias calculation
- writeByte(MPU6050_ADDRESS, USER_CTRL, 0x40); // Enable FIFO
- writeByte(MPU6050_ADDRESS, FIFO_EN, 0x78); // Enable gyro and accelerometer sensors for FIFO (max size 1024 bytes in MPU-6050)
- wait(0.08); // accumulate 80 samples in 80 milliseconds = 960 bytes
+ c = readByte (MPU6050_ADDRESS, ACCEL_CONFIG);
+ writeByte (MPU6050_ADDRESS, ACCEL_CONFIG,
+ c & ~0x07); // Clear high-pass filter bits [2:0]
+ writeByte (MPU6050_ADDRESS, ACCEL_CONFIG, c | 0x07); // Set ACCEL_HPF to 7;
+ // hold the initial
+ // accleration value
+ // as a referance
+
+ c = readByte (MPU6050_ADDRESS, PWR_MGMT_2);
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_2,
+ c & ~0xC7); // Clear standby XA, YA, and ZA bits [3:5] and
+ // LP_WAKE_CTRL bits [6:7]
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_2, c | 0x47); // Set wakeup frequency
+ // to 5 Hz, and disable
+ // XG, YG, and ZG gyros
+ // (bits [0:2])
-// At end of sample accumulation, turn off FIFO sensor read
- writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00); // Disable gyro and accelerometer sensors for FIFO
- readBytes(MPU6050_ADDRESS, FIFO_COUNTH, 2, &data[0]); // read FIFO sample count
- fifo_count = ((uint16_t)data[0] << 8) | data[1];
- packet_count = fifo_count/12;// How many sets of full gyro and accelerometer data for averaging
+ c = readByte (MPU6050_ADDRESS, PWR_MGMT_1);
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_1,
+ c & ~0x20); // Clear sleep and cycle bit 5
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_1, c | 0x20); // Set cycle bit 5 to
+ // begin low power
+ // accelerometer motion
+ // interrupts
+ }
+
+ void
+ resetMPU6050 ()
+ {
+ // reset device
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_1,
+ 0x80); // Write a one to bit 7 reset bit; toggle reset device
+ wait (0.1);
+ }
+
+ void
+ initMPU6050 ()
+ {
+ // Initialize MPU6050 device
+ // wake up device
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_1,
+ 0x00); // Clear sleep mode bit (6), enable all sensors
+ wait (0.1); // Delay 100 ms for PLL to get established on x-axis gyro;
+ // should check for PLL ready interrupt
+
+ // get stable time source
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_1, 0x01); // Set clock source to be
+ // PLL with x-axis gyroscope
+ // reference, bits 2:0 = 001
- for (ii = 0; ii < packet_count; ii++) {
- int16_t accel_temp[3] = {0, 0, 0}, gyro_temp[3] = {0, 0, 0};
- readBytes(MPU6050_ADDRESS, FIFO_R_W, 12, &data[0]); // read data for averaging
- accel_temp[0] = (int16_t) (((int16_t)data[0] << 8) | data[1] ) ; // Form signed 16-bit integer for each sample in FIFO
- accel_temp[1] = (int16_t) (((int16_t)data[2] << 8) | data[3] ) ;
- accel_temp[2] = (int16_t) (((int16_t)data[4] << 8) | data[5] ) ;
- gyro_temp[0] = (int16_t) (((int16_t)data[6] << 8) | data[7] ) ;
- gyro_temp[1] = (int16_t) (((int16_t)data[8] << 8) | data[9] ) ;
- gyro_temp[2] = (int16_t) (((int16_t)data[10] << 8) | data[11]) ;
-
- accel_bias[0] += (int32_t) accel_temp[0]; // Sum individual signed 16-bit biases to get accumulated signed 32-bit biases
- accel_bias[1] += (int32_t) accel_temp[1];
- accel_bias[2] += (int32_t) accel_temp[2];
- gyro_bias[0] += (int32_t) gyro_temp[0];
- gyro_bias[1] += (int32_t) gyro_temp[1];
- gyro_bias[2] += (int32_t) gyro_temp[2];
-
-}
- accel_bias[0] /= (int32_t) packet_count; // Normalize sums to get average count biases
- accel_bias[1] /= (int32_t) packet_count;
- accel_bias[2] /= (int32_t) packet_count;
- gyro_bias[0] /= (int32_t) packet_count;
- gyro_bias[1] /= (int32_t) packet_count;
- gyro_bias[2] /= (int32_t) packet_count;
-
- if(accel_bias[2] > 0L) {accel_bias[2] -= (int32_t) accelsensitivity;} // Remove gravity from the z-axis accelerometer bias calculation
- else {accel_bias[2] += (int32_t) accelsensitivity;}
-
-// Construct the gyro biases for push to the hardware gyro bias registers, which are reset to zero upon device startup
- data[0] = (-gyro_bias[0]/4 >> 8) & 0xFF; // Divide by 4 to get 32.9 LSB per deg/s to conform to expected bias input format
- data[1] = (-gyro_bias[0]/4) & 0xFF; // Biases are additive, so change sign on calculated average gyro biases
- data[2] = (-gyro_bias[1]/4 >> 8) & 0xFF;
- data[3] = (-gyro_bias[1]/4) & 0xFF;
- data[4] = (-gyro_bias[2]/4 >> 8) & 0xFF;
- data[5] = (-gyro_bias[2]/4) & 0xFF;
+ // Configure Gyro and Accelerometer
+ // Disable FSYNC and set accelerometer and gyro bandwidth to 44 and 42 Hz,
+ // respectively;
+ // DLPF_CFG = bits 2:0 = 010; this sets the sample rate at 1 kHz for both
+ // Maximum delay is 4.9 ms which is just over a 200 Hz maximum rate
+ writeByte (MPU6050_ADDRESS, CONFIG, 0x03);
+
+ // Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV)
+ writeByte (MPU6050_ADDRESS, SMPLRT_DIV,
+ 0x04); // Use a 200 Hz rate; the same rate set in CONFIG above
-// Push gyro biases to hardware registers
- writeByte(MPU6050_ADDRESS, XG_OFFS_USRH, data[0]);
- writeByte(MPU6050_ADDRESS, XG_OFFS_USRL, data[1]);
- writeByte(MPU6050_ADDRESS, YG_OFFS_USRH, data[2]);
- writeByte(MPU6050_ADDRESS, YG_OFFS_USRL, data[3]);
- writeByte(MPU6050_ADDRESS, ZG_OFFS_USRH, data[4]);
- writeByte(MPU6050_ADDRESS, ZG_OFFS_USRL, data[5]);
-
- dest1[0] = (float) gyro_bias[0]/(float) gyrosensitivity; // construct gyro bias in deg/s for later manual subtraction
- dest1[1] = (float) gyro_bias[1]/(float) gyrosensitivity;
- dest1[2] = (float) gyro_bias[2]/(float) gyrosensitivity;
+ // Set gyroscope full scale range
+ // Range selects FS_SEL and AFS_SEL are 0 - 3, so 2-bit values are
+ // left-shifted into positions 4:3
+ uint8_t c = readByte (MPU6050_ADDRESS, GYRO_CONFIG);
+ writeByte (MPU6050_ADDRESS, GYRO_CONFIG,
+ c & ~0xE0); // Clear self-test bits [7:5]
+ writeByte (MPU6050_ADDRESS, GYRO_CONFIG,
+ c & ~0x18); // Clear AFS bits [4:3]
+ writeByte (MPU6050_ADDRESS, GYRO_CONFIG,
+ c | Gscale << 3); // Set full scale range for the gyro
-// Construct the accelerometer biases for push to the hardware accelerometer bias registers. These registers contain
-// factory trim values which must be added to the calculated accelerometer biases; on boot up these registers will hold
-// non-zero values. In addition, bit 0 of the lower byte must be preserved since it is used for temperature
-// compensation calculations. Accelerometer bias registers expect bias input as 2048 LSB per g, so that
-// the accelerometer biases calculated above must be divided by 8.
+ // Set accelerometer configuration
+ c = readByte (MPU6050_ADDRESS, ACCEL_CONFIG);
+ writeByte (MPU6050_ADDRESS, ACCEL_CONFIG,
+ c & ~0xE0); // Clear self-test bits [7:5]
+ writeByte (MPU6050_ADDRESS, ACCEL_CONFIG,
+ c & ~0x18); // Clear AFS bits [4:3]
+ writeByte (MPU6050_ADDRESS, ACCEL_CONFIG,
+ c | Ascale << 3); // Set full scale range for the accelerometer
- int32_t accel_bias_reg[3] = {0, 0, 0}; // A place to hold the factory accelerometer trim biases
- readBytes(MPU6050_ADDRESS, XA_OFFSET_H, 2, &data[0]); // Read factory accelerometer trim values
- accel_bias_reg[0] = (int16_t) ((int16_t)data[0] << 8) | data[1];
- readBytes(MPU6050_ADDRESS, YA_OFFSET_H, 2, &data[0]);
- accel_bias_reg[1] = (int16_t) ((int16_t)data[0] << 8) | data[1];
- readBytes(MPU6050_ADDRESS, ZA_OFFSET_H, 2, &data[0]);
- accel_bias_reg[2] = (int16_t) ((int16_t)data[0] << 8) | data[1];
-
- uint32_t mask = 1uL; // Define mask for temperature compensation bit 0 of lower byte of accelerometer bias registers
- uint8_t mask_bit[3] = {0, 0, 0}; // Define array to hold mask bit for each accelerometer bias axis
-
- for(ii = 0; ii < 3; ii++) {
- if(accel_bias_reg[ii] & mask) mask_bit[ii] = 0x01; // If temperature compensation bit is set, record that fact in mask_bit
+ // Configure Interrupts and Bypass Enable
+ // Set interrupt pin active high, push-pull, and clear on read of
+ // INT_STATUS, enable I2C_BYPASS_EN so additional chips
+ // can join the I2C bus and all can be controlled by the Arduino as master
+ writeByte (MPU6050_ADDRESS, INT_PIN_CFG, 0x22);
+ writeByte (MPU6050_ADDRESS, INT_ENABLE,
+ 0x01); // Enable data ready (bit 0) interrupt
}
- // Construct total accelerometer bias, including calculated average accelerometer bias from above
- accel_bias_reg[0] -= (accel_bias[0]/8); // Subtract calculated averaged accelerometer bias scaled to 2048 LSB/g (16 g full scale)
- accel_bias_reg[1] -= (accel_bias[1]/8);
- accel_bias_reg[2] -= (accel_bias[2]/8);
-
- data[0] = (accel_bias_reg[0] >> 8) & 0xFF;
- data[1] = (accel_bias_reg[0]) & 0xFF;
- data[1] = data[1] | mask_bit[0]; // preserve temperature compensation bit when writing back to accelerometer bias registers
- data[2] = (accel_bias_reg[1] >> 8) & 0xFF;
- data[3] = (accel_bias_reg[1]) & 0xFF;
- data[3] = data[3] | mask_bit[1]; // preserve temperature compensation bit when writing back to accelerometer bias registers
- data[4] = (accel_bias_reg[2] >> 8) & 0xFF;
- data[5] = (accel_bias_reg[2]) & 0xFF;
- data[5] = data[5] | mask_bit[2]; // preserve temperature compensation bit when writing back to accelerometer bias registers
+ // Function which accumulates gyro and accelerometer data after device
+ // initialization. It calculates the average
+ // of the at-rest readings and then loads the resulting offsets into
+ // accelerometer and gyro bias registers.
+ void
+ calibrateMPU6050 (float *dest1, float *dest2)
+ {
+ uint8_t
+ data[12]; // data array to hold accelerometer and gyro x, y, z, data
+ uint16_t ii, packet_count, fifo_count;
+ int32_t gyro_bias[3] = { 0, 0, 0 }, accel_bias[3] = { 0, 0, 0 };
+
+ // reset device, reset all registers, clear gyro and accelerometer bias
+ // registers
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_1,
+ 0x80); // Write a one to bit 7 reset bit; toggle reset device
+ wait (0.1);
+
+ // get stable time source
+ // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 =
+ // 001
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_1, 0x01);
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_2, 0x00);
+ wait (0.2);
+
+ // Configure device for bias calculation
+ writeByte (MPU6050_ADDRESS, INT_ENABLE, 0x00); // Disable all interrupts
+ writeByte (MPU6050_ADDRESS, FIFO_EN, 0x00); // Disable FIFO
+ writeByte (MPU6050_ADDRESS, PWR_MGMT_1,
+ 0x00); // Turn on internal clock source
+ writeByte (MPU6050_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master
+ writeByte (MPU6050_ADDRESS, USER_CTRL,
+ 0x00); // Disable FIFO and I2C master modes
+ writeByte (MPU6050_ADDRESS, USER_CTRL, 0x0C); // Reset FIFO and DMP
+ wait (0.015);
+
+ // Configure MPU6050 gyro and accelerometer for bias calculation
+ writeByte (MPU6050_ADDRESS, CONFIG, 0x01); // Set low-pass filter to 188 Hz
+ writeByte (MPU6050_ADDRESS, SMPLRT_DIV, 0x00); // Set sample rate to 1 kHz
+ writeByte (MPU6050_ADDRESS, GYRO_CONFIG, 0x00); // Set gyro full-scale to
+ // 250 degrees per second,
+ // maximum sensitivity
+ writeByte (
+ MPU6050_ADDRESS, ACCEL_CONFIG,
+ 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity
+
+ uint16_t gyrosensitivity = 131; // = 131 LSB/degrees/sec
+ uint16_t accelsensitivity = 16384; // = 16384 LSB/g
- // Push accelerometer biases to hardware registers
-// writeByte(MPU6050_ADDRESS, XA_OFFSET_H, data[0]);
-// writeByte(MPU6050_ADDRESS, XA_OFFSET_L_TC, data[1]);
-// writeByte(MPU6050_ADDRESS, YA_OFFSET_H, data[2]);
-// writeByte(MPU6050_ADDRESS, YA_OFFSET_L_TC, data[3]);
-// writeByte(MPU6050_ADDRESS, ZA_OFFSET_H, data[4]);
-// writeByte(MPU6050_ADDRESS, ZA_OFFSET_L_TC, data[5]);
+ // Configure FIFO to capture accelerometer and gyro data for bias
+ // calculation
+ writeByte (MPU6050_ADDRESS, USER_CTRL, 0x40); // Enable FIFO
+ writeByte (MPU6050_ADDRESS, FIFO_EN, 0x78); // Enable gyro and
+ // accelerometer sensors for
+ // FIFO (max size 1024 bytes
+ // in MPU-6050)
+ wait (0.08); // accumulate 80 samples in 80 milliseconds = 960 bytes
+
+ // At end of sample accumulation, turn off FIFO sensor read
+ writeByte (MPU6050_ADDRESS, FIFO_EN,
+ 0x00); // Disable gyro and accelerometer sensors for FIFO
+ readBytes (MPU6050_ADDRESS, FIFO_COUNTH, 2,
+ &data[0]); // read FIFO sample count
+ fifo_count = ((uint16_t)data[0] << 8) | data[1];
+ packet_count = fifo_count / 12; // How many sets of full gyro and
+ // accelerometer data for averaging
-// Output scaled accelerometer biases for manual subtraction in the main program
- dest2[0] = (float)accel_bias[0]/(float)accelsensitivity;
- dest2[1] = (float)accel_bias[1]/(float)accelsensitivity;
- dest2[2] = (float)accel_bias[2]/(float)accelsensitivity;
-}
+ for (ii = 0; ii < packet_count; ii++)
+ {
+ int16_t accel_temp[3] = { 0, 0, 0 }, gyro_temp[3] = { 0, 0, 0 };
+ readBytes (MPU6050_ADDRESS, FIFO_R_W, 12,
+ &data[0]); // read data for averaging
+ accel_temp[0] = (int16_t) (
+ ((int16_t)data[0] << 8)
+ | data[1]); // Form signed 16-bit integer for each sample in FIFO
+ accel_temp[1] = (int16_t) (((int16_t)data[2] << 8) | data[3]);
+ accel_temp[2] = (int16_t) (((int16_t)data[4] << 8) | data[5]);
+ gyro_temp[0] = (int16_t) (((int16_t)data[6] << 8) | data[7]);
+ gyro_temp[1] = (int16_t) (((int16_t)data[8] << 8) | data[9]);
+ gyro_temp[2] = (int16_t) (((int16_t)data[10] << 8) | data[11]);
+ accel_bias[0] += (int32_t)accel_temp[0]; // Sum individual signed
+ // 16-bit biases to get
+ // accumulated signed 32-bit
+ // biases
+ accel_bias[1] += (int32_t)accel_temp[1];
+ accel_bias[2] += (int32_t)accel_temp[2];
+ gyro_bias[0] += (int32_t)gyro_temp[0];
+ gyro_bias[1] += (int32_t)gyro_temp[1];
+ gyro_bias[2] += (int32_t)gyro_temp[2];
+ }
+ accel_bias[0]
+ /= (int32_t)packet_count; // Normalize sums to get average count biases
+ accel_bias[1] /= (int32_t)packet_count;
+ accel_bias[2] /= (int32_t)packet_count;
+ gyro_bias[0] /= (int32_t)packet_count;
+ gyro_bias[1] /= (int32_t)packet_count;
+ gyro_bias[2] /= (int32_t)packet_count;
-// Accelerometer and gyroscope self test; check calibration wrt factory settings
-void MPU6050SelfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass
-{
- uint8_t rawData[4] = {0, 0, 0, 0};
- uint8_t selfTest[6];
- float factoryTrim[6];
-
- // Configure the accelerometer for self-test
- writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0xF0); // Enable self test on all three axes and set accelerometer range to +/- 8 g
- writeByte(MPU6050_ADDRESS, GYRO_CONFIG, 0xE0); // Enable self test on all three axes and set gyro range to +/- 250 degrees/s
- wait(0.25); // Delay a while to let the device execute the self-test
- rawData[0] = readByte(MPU6050_ADDRESS, SELF_TEST_X); // X-axis self-test results
- rawData[1] = readByte(MPU6050_ADDRESS, SELF_TEST_Y); // Y-axis self-test results
- rawData[2] = readByte(MPU6050_ADDRESS, SELF_TEST_Z); // Z-axis self-test results
- rawData[3] = readByte(MPU6050_ADDRESS, SELF_TEST_A); // Mixed-axis self-test results
- // Extract the acceleration test results first
- selfTest[0] = (rawData[0] >> 3) | (rawData[3] & 0x30) >> 4 ; // XA_TEST result is a five-bit unsigned integer
- selfTest[1] = (rawData[1] >> 3) | (rawData[3] & 0x0C) >> 4 ; // YA_TEST result is a five-bit unsigned integer
- selfTest[2] = (rawData[2] >> 3) | (rawData[3] & 0x03) >> 4 ; // ZA_TEST result is a five-bit unsigned integer
- // Extract the gyration test results first
- selfTest[3] = rawData[0] & 0x1F ; // XG_TEST result is a five-bit unsigned integer
- selfTest[4] = rawData[1] & 0x1F ; // YG_TEST result is a five-bit unsigned integer
- selfTest[5] = rawData[2] & 0x1F ; // ZG_TEST result is a five-bit unsigned integer
- // Process results to allow final comparison with factory set values
- factoryTrim[0] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[0] - 1.0f)/30.0f))); // FT[Xa] factory trim calculation
- factoryTrim[1] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[1] - 1.0f)/30.0f))); // FT[Ya] factory trim calculation
- factoryTrim[2] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[2] - 1.0f)/30.0f))); // FT[Za] factory trim calculation
- factoryTrim[3] = ( 25.0f*131.0f)*(pow( 1.046f , (selfTest[3] - 1.0f) )); // FT[Xg] factory trim calculation
- factoryTrim[4] = (-25.0f*131.0f)*(pow( 1.046f , (selfTest[4] - 1.0f) )); // FT[Yg] factory trim calculation
- factoryTrim[5] = ( 25.0f*131.0f)*(pow( 1.046f , (selfTest[5] - 1.0f) )); // FT[Zg] factory trim calculation
-
- // Output self-test results and factory trim calculation if desired
- // Serial.println(selfTest[0]); Serial.println(selfTest[1]); Serial.println(selfTest[2]);
- // Serial.println(selfTest[3]); Serial.println(selfTest[4]); Serial.println(selfTest[5]);
- // Serial.println(factoryTrim[0]); Serial.println(factoryTrim[1]); Serial.println(factoryTrim[2]);
- // Serial.println(factoryTrim[3]); Serial.println(factoryTrim[4]); Serial.println(factoryTrim[5]);
+ if (accel_bias[2] > 0L)
+ {
+ accel_bias[2] -= (int32_t)accelsensitivity;
+ } // Remove gravity from the z-axis accelerometer bias calculation
+ else
+ {
+ accel_bias[2] += (int32_t)accelsensitivity;
+ }
+
+ // Construct the gyro biases for push to the hardware gyro bias registers,
+ // which are reset to zero upon device startup
+ data[0] = (-gyro_bias[0] / 4 >> 8) & 0xFF; // Divide by 4 to get 32.9 LSB
+ // per deg/s to conform to
+ // expected bias input format
+ data[1] = (-gyro_bias[0] / 4) & 0xFF; // Biases are additive, so change
+ // sign on calculated average gyro
+ // biases
+ data[2] = (-gyro_bias[1] / 4 >> 8) & 0xFF;
+ data[3] = (-gyro_bias[1] / 4) & 0xFF;
+ data[4] = (-gyro_bias[2] / 4 >> 8) & 0xFF;
+ data[5] = (-gyro_bias[2] / 4) & 0xFF;
+
+ // Push gyro biases to hardware registers
+ writeByte (MPU6050_ADDRESS, XG_OFFS_USRH, data[0]);
+ writeByte (MPU6050_ADDRESS, XG_OFFS_USRL, data[1]);
+ writeByte (MPU6050_ADDRESS, YG_OFFS_USRH, data[2]);
+ writeByte (MPU6050_ADDRESS, YG_OFFS_USRL, data[3]);
+ writeByte (MPU6050_ADDRESS, ZG_OFFS_USRH, data[4]);
+ writeByte (MPU6050_ADDRESS, ZG_OFFS_USRL, data[5]);
+
+ dest1[0] = (float)gyro_bias[0]
+ / (float)gyrosensitivity; // construct gyro bias in deg/s for
+ // later manual subtraction
+ dest1[1] = (float)gyro_bias[1] / (float)gyrosensitivity;
+ dest1[2] = (float)gyro_bias[2] / (float)gyrosensitivity;
+
+ // Construct the accelerometer biases for push to the hardware
+ // accelerometer bias registers. These registers contain
+ // factory trim values which must be added to the calculated accelerometer
+ // biases; on boot up these registers will hold
+ // non-zero values. In addition, bit 0 of the lower byte must be preserved
+ // since it is used for temperature
+ // compensation calculations. Accelerometer bias registers expect bias
+ // input as 2048 LSB per g, so that
+ // the accelerometer biases calculated above must be divided by 8.
- // Report results as a ratio of (STR - FT)/FT; the change from Factory Trim of the Self-Test Response
- // To get to percent, must multiply by 100 and subtract result from 100
- for (int i = 0; i < 6; i++) {
- destination[i] = 100.0f + 100.0f*(selfTest[i] - factoryTrim[i])/factoryTrim[i]; // Report percent differences
- }
-
-}
+ int32_t accel_bias_reg[3]
+ = { 0, 0, 0 }; // A place to hold the factory accelerometer trim biases
+ readBytes (MPU6050_ADDRESS, XA_OFFSET_H, 2,
+ &data[0]); // Read factory accelerometer trim values
+ accel_bias_reg[0] = (int16_t) ((int16_t)data[0] << 8) | data[1];
+ readBytes (MPU6050_ADDRESS, YA_OFFSET_H, 2, &data[0]);
+ accel_bias_reg[1] = (int16_t) ((int16_t)data[0] << 8) | data[1];
+ readBytes (MPU6050_ADDRESS, ZA_OFFSET_H, 2, &data[0]);
+ accel_bias_reg[2] = (int16_t) ((int16_t)data[0] << 8) | data[1];
+
+ uint32_t mask = 1uL; // Define mask for temperature compensation bit 0 of
+ // lower byte of accelerometer bias registers
+ uint8_t mask_bit[3] = {
+ 0, 0, 0
+ }; // Define array to hold mask bit for each accelerometer bias axis
+
+ for (ii = 0; ii < 3; ii++)
+ {
+ if (accel_bias_reg[ii] & mask)
+ mask_bit[ii] = 0x01; // If temperature compensation bit is set,
+ // record that fact in mask_bit
+ }
+ // Construct total accelerometer bias, including calculated average
+ // accelerometer bias from above
+ accel_bias_reg[0] -= (accel_bias[0] / 8); // Subtract calculated averaged
+ // accelerometer bias scaled to
+ // 2048 LSB/g (16 g full scale)
+ accel_bias_reg[1] -= (accel_bias[1] / 8);
+ accel_bias_reg[2] -= (accel_bias[2] / 8);
+
+ data[0] = (accel_bias_reg[0] >> 8) & 0xFF;
+ data[1] = (accel_bias_reg[0]) & 0xFF;
+ data[1] = data[1] | mask_bit[0]; // preserve temperature compensation bit
+ // when writing back to accelerometer bias
+ // registers
+ data[2] = (accel_bias_reg[1] >> 8) & 0xFF;
+ data[3] = (accel_bias_reg[1]) & 0xFF;
+ data[3] = data[3] | mask_bit[1]; // preserve temperature compensation bit
+ // when writing back to accelerometer bias
+ // registers
+ data[4] = (accel_bias_reg[2] >> 8) & 0xFF;
+ data[5] = (accel_bias_reg[2]) & 0xFF;
+ data[5] = data[5] | mask_bit[2]; // preserve temperature compensation bit
+ // when writing back to accelerometer bias
+ // registers
+
+ // Push accelerometer biases to hardware registers
+ // writeByte(MPU6050_ADDRESS, XA_OFFSET_H, data[0]);
+ // writeByte(MPU6050_ADDRESS, XA_OFFSET_L_TC, data[1]);
+ // writeByte(MPU6050_ADDRESS, YA_OFFSET_H, data[2]);
+ // writeByte(MPU6050_ADDRESS, YA_OFFSET_L_TC, data[3]);
+ // writeByte(MPU6050_ADDRESS, ZA_OFFSET_H, data[4]);
+ // writeByte(MPU6050_ADDRESS, ZA_OFFSET_L_TC, data[5]);
-// Implementation of Sebastian Madgwick's "...efficient orientation filter for... inertial/magnetic sensor arrays"
-// (see http://www.x-io.co.uk/category/open-source/ for examples and more details)
-// which fuses acceleration and rotation rate to produce a quaternion-based estimate of relative
-// device orientation -- which can be converted to yaw, pitch, and roll. Useful for stabilizing quadcopters, etc.
-// The performance of the orientation filter is at least as good as conventional Kalman-based filtering algorithms
-// but is much less computationally intensive---it can be performed on a 3.3 V Pro Mini operating at 8 MHz!
- void MadgwickQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz)
- {
- float q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3]; // short name local variable for readability
- float norm; // vector norm
- float f1, f2, f3; // objective funcyion elements
- float J_11or24, J_12or23, J_13or22, J_14or21, J_32, J_33; // objective function Jacobian elements
- float qDot1, qDot2, qDot3, qDot4;
- float hatDot1, hatDot2, hatDot3, hatDot4;
- float gerrx, gerry, gerrz, gbiasx, gbiasy, gbiasz; // gyro bias error
+ // Output scaled accelerometer biases for manual subtraction in the main
+ // program
+ dest2[0] = (float)accel_bias[0] / (float)accelsensitivity;
+ dest2[1] = (float)accel_bias[1] / (float)accelsensitivity;
+ dest2[2] = (float)accel_bias[2] / (float)accelsensitivity;
+ }
+
+ // Accelerometer and gyroscope self test; check calibration wrt factory
+ // settings
+ void MPU6050SelfTest (float *destination) // Should return percent deviation
+ // from factory trim values, +/- 14
+ // or less deviation is a pass
+ {
+ uint8_t rawData[4] = { 0, 0, 0, 0 };
+ uint8_t selfTest[6];
+ float factoryTrim[6];
- // Auxiliary variables to avoid repeated arithmetic
- float _halfq1 = 0.5f * q1;
- float _halfq2 = 0.5f * q2;
- float _halfq3 = 0.5f * q3;
- float _halfq4 = 0.5f * q4;
- float _2q1 = 2.0f * q1;
- float _2q2 = 2.0f * q2;
- float _2q3 = 2.0f * q3;
- float _2q4 = 2.0f * q4;
-// float _2q1q3 = 2.0f * q1 * q3;
-// float _2q3q4 = 2.0f * q3 * q4;
+ // Configure the accelerometer for self-test
+ writeByte (MPU6050_ADDRESS, ACCEL_CONFIG, 0xF0); // Enable self test on all
+ // three axes and set
+ // accelerometer range to
+ // +/- 8 g
+ writeByte (MPU6050_ADDRESS, GYRO_CONFIG, 0xE0); // Enable self test on all
+ // three axes and set gyro
+ // range to +/- 250
+ // degrees/s
+ wait (0.25); // Delay a while to let the device execute the self-test
+ // rawData[0]
+ // = readByte (MPU6050_ADDRESS, SELF_TEST_X); // X-axis self-test
+ // results
+ // rawData[1]
+ // = readByte (MPU6050_ADDRESS, SELF_TEST_Y); // Y-axis self-test
+ // results
+ // rawData[2]
+ // = readByte (MPU6050_ADDRESS, SELF_TEST_Z); // Z-axis self-test
+ // results
+ // rawData[3] = readByte (MPU6050_ADDRESS,
+ // SELF_TEST_A);
+ // Mixed-axis self-test results
+ // Extract the acceleration test results first
+ selfTest[0] = (rawData[0] >> 3)
+ | (rawData[3] & 0x30)
+ >> 4; // XA_TEST result is a five-bit unsigned integer
+ selfTest[1] = (rawData[1] >> 3)
+ | (rawData[3] & 0x0C)
+ >> 4; // YA_TEST result is a five-bit unsigned integer
+ selfTest[2] = (rawData[2] >> 3)
+ | (rawData[3] & 0x03)
+ >> 4; // ZA_TEST result is a five-bit unsigned integer
+ // Extract the gyration test results first
+ selfTest[3]
+ = rawData[0] & 0x1F; // XG_TEST result is a five-bit unsigned integer
+ selfTest[4]
+ = rawData[1] & 0x1F; // YG_TEST result is a five-bit unsigned integer
+ selfTest[5]
+ = rawData[2] & 0x1F; // ZG_TEST result is a five-bit unsigned integer
+ // Process results to allow final comparison with factory set values
+ factoryTrim[0] = (4096.0f * 0.34f)
+ * (pow ((0.92f / 0.34f),
+ ((selfTest[0] - 1.0f)
+ / 30.0f))); // FT[Xa] factory trim calculation
+ factoryTrim[1] = (4096.0f * 0.34f)
+ * (pow ((0.92f / 0.34f),
+ ((selfTest[1] - 1.0f)
+ / 30.0f))); // FT[Ya] factory trim calculation
+ factoryTrim[2] = (4096.0f * 0.34f)
+ * (pow ((0.92f / 0.34f),
+ ((selfTest[2] - 1.0f)
+ / 30.0f))); // FT[Za] factory trim calculation
+ factoryTrim[3]
+ = (25.0f * 131.0f)
+ * (pow (1.046f,
+ (selfTest[3] - 1.0f))); // FT[Xg] factory trim calculation
+ factoryTrim[4]
+ = (-25.0f * 131.0f)
+ * (pow (1.046f,
+ (selfTest[4] - 1.0f))); // FT[Yg] factory trim calculation
+ factoryTrim[5]
+ = (25.0f * 131.0f)
+ * (pow (1.046f,
+ (selfTest[5] - 1.0f))); // FT[Zg] factory trim calculation
+
+ // Output self-test results and factory trim calculation if desired
+ // Serial.println(selfTest[0]); Serial.println(selfTest[1]);
+ // Serial.println(selfTest[2]);
+ // Serial.println(selfTest[3]); Serial.println(selfTest[4]);
+ // Serial.println(selfTest[5]);
+ // Serial.println(factoryTrim[0]); Serial.println(factoryTrim[1]);
+ // Serial.println(factoryTrim[2]);
+ // Serial.println(factoryTrim[3]); Serial.println(factoryTrim[4]);
+ // Serial.println(factoryTrim[5]);
+
+ // Report results as a ratio of (STR - FT)/FT; the change from Factory Trim
+ // of the Self-Test Response
+ // To get to percent, must multiply by 100 and subtract result from 100
+ for (int i = 0; i < 6; i++)
+ {
+ destination[i] = 100.0f
+ + 100.0f * (selfTest[i] - factoryTrim[i])
+ / factoryTrim[i]; // Report percent differences
+ }
+ }
- // Normalise accelerometer measurement
- norm = sqrt(ax * ax + ay * ay + az * az);
- if (norm == 0.0f) return; // handle NaN
- norm = 1.0f/norm;
- ax *= norm;
- ay *= norm;
- az *= norm;
-
- // Compute the objective function and Jacobian
- f1 = _2q2 * q4 - _2q1 * q3 - ax;
- f2 = _2q1 * q2 + _2q3 * q4 - ay;
- f3 = 1.0f - _2q2 * q2 - _2q3 * q3 - az;
- J_11or24 = _2q3;
- J_12or23 = _2q4;
- J_13or22 = _2q1;
- J_14or21 = _2q2;
- J_32 = 2.0f * J_14or21;
- J_33 = 2.0f * J_11or24;
-
- // Compute the gradient (matrix multiplication)
- hatDot1 = J_14or21 * f2 - J_11or24 * f1;
- hatDot2 = J_12or23 * f1 + J_13or22 * f2 - J_32 * f3;
- hatDot3 = J_12or23 * f2 - J_33 *f3 - J_13or22 * f1;
- hatDot4 = J_14or21 * f1 + J_11or24 * f2;
-
- // Normalize the gradient
- norm = sqrt(hatDot1 * hatDot1 + hatDot2 * hatDot2 + hatDot3 * hatDot3 + hatDot4 * hatDot4);
- hatDot1 /= norm;
- hatDot2 /= norm;
- hatDot3 /= norm;
- hatDot4 /= norm;
-
- // Compute estimated gyroscope biases
- gerrx = _2q1 * hatDot2 - _2q2 * hatDot1 - _2q3 * hatDot4 + _2q4 * hatDot3;
- gerry = _2q1 * hatDot3 + _2q2 * hatDot4 - _2q3 * hatDot1 - _2q4 * hatDot2;
- gerrz = _2q1 * hatDot4 - _2q2 * hatDot3 + _2q3 * hatDot2 - _2q4 * hatDot1;
-
- // Compute and remove gyroscope biases
- gbiasx += gerrx * deltat * zeta;
- gbiasy += gerry * deltat * zeta;
- gbiasz += gerrz * deltat * zeta;
- // gx -= gbiasx;
- // gy -= gbiasy;
- // gz -= gbiasz;
-
- // Compute the quaternion derivative
- qDot1 = -_halfq2 * gx - _halfq3 * gy - _halfq4 * gz;
- qDot2 = _halfq1 * gx + _halfq3 * gz - _halfq4 * gy;
- qDot3 = _halfq1 * gy - _halfq2 * gz + _halfq4 * gx;
- qDot4 = _halfq1 * gz + _halfq2 * gy - _halfq3 * gx;
+ // Implementation of Sebastian Madgwick's "...efficient orientation filter
+ // for... inertial/magnetic sensor arrays"
+ // (see http://www.x-io.co.uk/category/open-source/ for examples and more
+ // details)
+ // which fuses acceleration and rotation rate to produce a quaternion-based
+ // estimate of relative
+ // device orientation -- which can be converted to yaw, pitch, and roll.
+ // Useful for stabilizing quadcopters, etc.
+ // The performance of the orientation filter is at least as good as
+ // conventional Kalman-based filtering algorithms
+ // but is much less computationally intensive---it can be performed on a 3.3
+ // V Pro Mini operating at 8 MHz!
+ void
+ MadgwickQuaternionUpdate (float ax, float ay, float az, float gx, float gy,
+ float gz)
+ {
+ float q1 = q[0], q2 = q[1], q3 = q[2],
+ q4 = q[3]; // short name local variable for readability
+ float norm; // vector norm
+ float f1, f2, f3; // objective funcyion elements
+ float J_11or24, J_12or23, J_13or22, J_14or21, J_32,
+ J_33; // objective function Jacobian elements
+ float qDot1, qDot2, qDot3, qDot4;
+ float hatDot1, hatDot2, hatDot3, hatDot4;
+ float gerrx, gerry, gerrz, gbiasx, gbiasy, gbiasz; // gyro bias error
+
+ // Auxiliary variables to avoid repeated arithmetic
+ float _halfq1 = 0.5f * q1;
+ float _halfq2 = 0.5f * q2;
+ float _halfq3 = 0.5f * q3;
+ float _halfq4 = 0.5f * q4;
+ float _2q1 = 2.0f * q1;
+ float _2q2 = 2.0f * q2;
+ float _2q3 = 2.0f * q3;
+ float _2q4 = 2.0f * q4;
+ // float _2q1q3 = 2.0f * q1 * q3;
+ // float _2q3q4 = 2.0f * q3 * q4;
+
+ // Normalise accelerometer measurement
+ norm = sqrt (ax * ax + ay * ay + az * az);
+ if (norm == 0.0f)
+ return; // handle NaN
+ norm = 1.0f / norm;
+ ax *= norm;
+ ay *= norm;
+ az *= norm;
- // Compute then integrate estimated quaternion derivative
- q1 += (qDot1 -(beta * hatDot1)) * deltat;
- q2 += (qDot2 -(beta * hatDot2)) * deltat;
- q3 += (qDot3 -(beta * hatDot3)) * deltat;
- q4 += (qDot4 -(beta * hatDot4)) * deltat;
+ // Compute the objective function and Jacobian
+ f1 = _2q2 * q4 - _2q1 * q3 - ax;
+ f2 = _2q1 * q2 + _2q3 * q4 - ay;
+ f3 = 1.0f - _2q2 * q2 - _2q3 * q3 - az;
+ J_11or24 = _2q3;
+ J_12or23 = _2q4;
+ J_13or22 = _2q1;
+ J_14or21 = _2q2;
+ J_32 = 2.0f * J_14or21;
+ J_33 = 2.0f * J_11or24;
+
+ // Compute the gradient (matrix multiplication)
+ hatDot1 = J_14or21 * f2 - J_11or24 * f1;
+ hatDot2 = J_12or23 * f1 + J_13or22 * f2 - J_32 * f3;
+ hatDot3 = J_12or23 * f2 - J_33 * f3 - J_13or22 * f1;
+ hatDot4 = J_14or21 * f1 + J_11or24 * f2;
+
+ // Normalize the gradient
+ norm = sqrt (hatDot1 * hatDot1 + hatDot2 * hatDot2 + hatDot3 * hatDot3
+ + hatDot4 * hatDot4);
+ hatDot1 /= norm;
+ hatDot2 /= norm;
+ hatDot3 /= norm;
+ hatDot4 /= norm;
+
+ // Compute estimated gyroscope biases
+ gerrx = _2q1 * hatDot2 - _2q2 * hatDot1 - _2q3 * hatDot4 + _2q4 * hatDot3;
+ gerry = _2q1 * hatDot3 + _2q2 * hatDot4 - _2q3 * hatDot1 - _2q4 * hatDot2;
+ gerrz = _2q1 * hatDot4 - _2q2 * hatDot3 + _2q3 * hatDot2 - _2q4 * hatDot1;
- // Normalize the quaternion
- norm = sqrt(q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4); // normalise quaternion
- norm = 1.0f/norm;
- q[0] = q1 * norm;
- q[1] = q2 * norm;
- q[2] = q3 * norm;
- q[3] = q4 * norm;
-
- }
-
-
- };
+ // Compute and remove gyroscope biases
+ gbiasx += gerrx * deltat * zeta;
+ gbiasy += gerry * deltat * zeta;
+ gbiasz += gerrz * deltat * zeta;
+ // gx -= gbiasx;
+ // gy -= gbiasy;
+ // gz -= gbiasz;
+
+ // Compute the quaternion derivative
+ qDot1 = -_halfq2 * gx - _halfq3 * gy - _halfq4 * gz;
+ qDot2 = _halfq1 * gx + _halfq3 * gz - _halfq4 * gy;
+ qDot3 = _halfq1 * gy - _halfq2 * gz + _halfq4 * gx;
+ qDot4 = _halfq1 * gz + _halfq2 * gy - _halfq3 * gx;
+
+ // Compute then integrate estimated quaternion derivative
+ q1 += (qDot1 - (beta * hatDot1)) * deltat;
+ q2 += (qDot2 - (beta * hatDot2)) * deltat;
+ q3 += (qDot3 - (beta * hatDot3)) * deltat;
+ q4 += (qDot4 - (beta * hatDot4)) * deltat;
+
+ // Normalize the quaternion
+ norm
+ = sqrt (q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4); // normalise quaternion
+ norm = 1.0f / norm;
+ q[0] = q1 * norm;
+ q[1] = q2 * norm;
+ q[2] = q3 * norm;
+ q[3] = q4 * norm;
+ }
+};
#endif
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