Yuxiang Yang
Dependents: controller_with_backup
MPU6050.h
- Committer:
- yxyang
- Date:
- 2017-05-30
- Revision:
- 0:d23cb6fd82b7
File content as of revision 0:d23cb6fd82b7:
#ifndef MPU6050_H
#define MPU6050_H
#include "math.h"
#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
//
#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
#define EXT_SENS_DATA_03 0x4C
#define EXT_SENS_DATA_04 0x4D
#define EXT_SENS_DATA_05 0x4E
#define EXT_SENS_DATA_06 0x4F
#define EXT_SENS_DATA_07 0x50
#define EXT_SENS_DATA_08 0x51
#define EXT_SENS_DATA_09 0x52
#define EXT_SENS_DATA_10 0x53
#define EXT_SENS_DATA_11 0x54
#define EXT_SENS_DATA_12 0x55
#define EXT_SENS_DATA_13 0x56
#define EXT_SENS_DATA_14 0x57
#define EXT_SENS_DATA_15 0x58
#define EXT_SENS_DATA_16 0x59
#define EXT_SENS_DATA_17 0x5A
#define EXT_SENS_DATA_18 0x5B
#define EXT_SENS_DATA_19 0x5C
#define EXT_SENS_DATA_20 0x5D
#define EXT_SENS_DATA_21 0x5E
#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_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 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
// 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
#else
#define MPU6050_ADDRESS 0x68 << 1 // Device address when ADO = 0
#endif
// Set initial input parameters
enum Ascale
{
AFS_2G = 0,
AFS_4G,
AFS_8G,
AFS_16G
};
enum Gscale
{
GFS_250DPS = 0,
GFS_500DPS,
GFS_1000DPS,
GFS_2000DPS
};
// Specify sensor full scale
int Gscale = GFS_250DPS;
int Ascale = AFS_2G;
// Set up I2C, (SDA,SCL)
#define MPU_SDA p9
#define MPU_SCL p10
I2C i2c (MPU_SDA, MPU_SCL);
// 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
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];
int delt_t = 0; // used to control display output rate
int count = 0; // used to control display output rate
// 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 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
class MPU6050
{
protected:
public:
//===================================================================================================================
//====== 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);
}
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];
}
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];
}
}
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)
{
// 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;
}
}
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]);
}
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 ()
{
// 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
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])
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
// 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
// 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
}
// 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
// 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
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;
// 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.
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]);
// 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];
// 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
}
}
// 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 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;
// 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