Bradley Kohler / MPU6050

MPU6050 module library

All credit to kriswiner @https://github.com/kriswiner. Just changed some code for my own purposes

MPU6050.cpp@1:ca4d8c044898, 2017-11-21 (annotated)

Committer:
kohlerba
Date:
Tue Nov 21 20:30:56 2017 +0000
Revision:
1:ca4d8c044898
Parent:
0:8a2cac9ba89e 
MPU6050 module library

Who changed what in which revision?

UserRevisionLine numberNew contents of line
kohlerba 0:8a2cac9ba89e 1 #include "mpu6050.h"
kohlerba 0:8a2cac9ba89e 2
kohlerba 0:8a2cac9ba89e 3 int Gscale = GFS_250DPS;
kohlerba 0:8a2cac9ba89e 4 int Ascale = AFS_2G;
kohlerba 0:8a2cac9ba89e 5
kohlerba 0:8a2cac9ba89e 6 I2C i2c(I2C_SDA, I2C_SCL);
kohlerba 0:8a2cac9ba89e 7
kohlerba 0:8a2cac9ba89e 8 float aRes, gRes;
kohlerba 0:8a2cac9ba89e 9
kohlerba 0:8a2cac9ba89e 10 int intPin = 12;
kohlerba 0:8a2cac9ba89e 11
kohlerba 0:8a2cac9ba89e 12 int16_t accelCount[3]; // Stores the 16-bit signed accelerometer sensor output
kohlerba 0:8a2cac9ba89e 13 float ax, ay, az; // Stores the real accel value in g's
kohlerba 0:8a2cac9ba89e 14 int16_t gyroCount[3]; // Stores the 16-bit signed gyro sensor output
kohlerba 0:8a2cac9ba89e 15 float gx, gy, gz; // Stores the real gyro value in degrees per seconds
kohlerba 0:8a2cac9ba89e 16 float gyroBias[3] = {0, 0, 0}, accelBias[3] = {0, 0, 0}; // Bias corrections for gyro and accelerometer
kohlerba 0:8a2cac9ba89e 17 int16_t tempCount; // Stores the real internal chip temperature in degrees Celsius
kohlerba 0:8a2cac9ba89e 18 float temperature;
kohlerba 0:8a2cac9ba89e 19 float SelfTest[6];
kohlerba 0:8a2cac9ba89e 20
kohlerba 0:8a2cac9ba89e 21 int delt_t = 0; // used to control display output rate
kohlerba 0:8a2cac9ba89e 22 int count = 0; // used to control display output rate
kohlerba 0:8a2cac9ba89e 23
kohlerba 0:8a2cac9ba89e 24 // parameters for 6 DoF sensor fusion calculations
kohlerba 0:8a2cac9ba89e 25 //float PI = 3.14159265358979323846f;
kohlerba 0:8a2cac9ba89e 26 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
kohlerba 0:8a2cac9ba89e 27 float beta = sqrt(3.0f / 4.0f) * GyroMeasError; // compute beta
kohlerba 0:8a2cac9ba89e 28 float GyroMeasDrift = PI * (1.0f / 180.0f); // gyroscope measurement drift in rad/s/s (start at 0.0 deg/s/s)
kohlerba 0:8a2cac9ba89e 29 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
kohlerba 0:8a2cac9ba89e 30 float pitch, yaw, roll;
kohlerba 0:8a2cac9ba89e 31 float deltat = 0.0f; // integration interval for both filter schemes
kohlerba 0:8a2cac9ba89e 32 int lastUpdate = 0, firstUpdate = 0, Now = 0; // used to calculate integration interval // used to calculate integration interval
kohlerba 0:8a2cac9ba89e 33 float q[4] = {1.0f, 0.0f, 0.0f, 0.0f}; // vector to hold quaternion
kohlerba 0:8a2cac9ba89e 34
kohlerba 0:8a2cac9ba89e 35 void mpu6050::writeByte(uint8_t address, uint8_t subAddress, uint8_t data){
kohlerba 0:8a2cac9ba89e 36 char data_write[2];
kohlerba 0:8a2cac9ba89e 37 data_write[0] = subAddress;
kohlerba 0:8a2cac9ba89e 38 data_write[1] = data;
kohlerba 0:8a2cac9ba89e 39 i2c.write(address, data_write, 2, 0);
kohlerba 0:8a2cac9ba89e 40 }
kohlerba 0:8a2cac9ba89e 41
kohlerba 0:8a2cac9ba89e 42 char mpu6050::readByte(uint8_t address, uint8_t subAddress){
kohlerba 0:8a2cac9ba89e 43 char data[1]; // `data` will store the register data
kohlerba 0:8a2cac9ba89e 44 char data_write[1];
kohlerba 0:8a2cac9ba89e 45 data_write[0] = subAddress;
kohlerba 0:8a2cac9ba89e 46 i2c.write(address, data_write, 1, 1); // no stop
kohlerba 0:8a2cac9ba89e 47 i2c.read(address, data, 1, 0);
kohlerba 0:8a2cac9ba89e 48 return data[0];
kohlerba 0:8a2cac9ba89e 49 }
kohlerba 0:8a2cac9ba89e 50
kohlerba 0:8a2cac9ba89e 51 void mpu6050::readBytes(uint8_t address, uint8_t subAddress, uint8_t count, uint8_t * dest){
kohlerba 0:8a2cac9ba89e 52 char data[14];
kohlerba 0:8a2cac9ba89e 53 char data_write[1];
kohlerba 0:8a2cac9ba89e 54 data_write[0] = subAddress;
kohlerba 0:8a2cac9ba89e 55 i2c.write(address, data_write, 1, 1); // no stop
kohlerba 0:8a2cac9ba89e 56 i2c.read(address, data, count, 0);
kohlerba 0:8a2cac9ba89e 57 for(int ii = 0; ii < count; ii++) {
kohlerba 0:8a2cac9ba89e 58 dest[ii] = data[ii];
kohlerba 0:8a2cac9ba89e 59 }
kohlerba 0:8a2cac9ba89e 60 }
kohlerba 0:8a2cac9ba89e 61
kohlerba 0:8a2cac9ba89e 62 void mpu6050::getGres() {
kohlerba 0:8a2cac9ba89e 63 switch (Gscale)
kohlerba 0:8a2cac9ba89e 64 {
kohlerba 0:8a2cac9ba89e 65 // Possible gyro scales (and their register bit settings) are:
kohlerba 0:8a2cac9ba89e 66 // 250 DPS (00), 500 DPS (01), 1000 DPS (10), and 2000 DPS (11).
kohlerba 0:8a2cac9ba89e 67 // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value:
kohlerba 0:8a2cac9ba89e 68 case GFS_250DPS:
kohlerba 0:8a2cac9ba89e 69 gRes = 250.0/32768.0;
kohlerba 0:8a2cac9ba89e 70 break;
kohlerba 0:8a2cac9ba89e 71 case GFS_500DPS:
kohlerba 0:8a2cac9ba89e 72 gRes = 500.0/32768.0;
kohlerba 0:8a2cac9ba89e 73 break;
kohlerba 0:8a2cac9ba89e 74 case GFS_1000DPS:
kohlerba 0:8a2cac9ba89e 75 gRes = 1000.0/32768.0;
kohlerba 0:8a2cac9ba89e 76 break;
kohlerba 0:8a2cac9ba89e 77 case GFS_2000DPS:
kohlerba 0:8a2cac9ba89e 78 gRes = 2000.0/32768.0;
kohlerba 0:8a2cac9ba89e 79 break;
kohlerba 0:8a2cac9ba89e 80 }
kohlerba 0:8a2cac9ba89e 81 }
kohlerba 0:8a2cac9ba89e 82
kohlerba 0:8a2cac9ba89e 83 void mpu6050::getAres() {
kohlerba 0:8a2cac9ba89e 84 switch (Ascale)
kohlerba 0:8a2cac9ba89e 85 {
kohlerba 0:8a2cac9ba89e 86 // Possible accelerometer scales (and their register bit settings) are:
kohlerba 0:8a2cac9ba89e 87 // 2 Gs (00), 4 Gs (01), 8 Gs (10), and 16 Gs (11).
kohlerba 0:8a2cac9ba89e 88 // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value:
kohlerba 0:8a2cac9ba89e 89 case AFS_2G:
kohlerba 0:8a2cac9ba89e 90 aRes = 2.0/32768.0;
kohlerba 0:8a2cac9ba89e 91 break;
kohlerba 0:8a2cac9ba89e 92 case AFS_4G:
kohlerba 0:8a2cac9ba89e 93 aRes = 4.0/32768.0;
kohlerba 0:8a2cac9ba89e 94 break;
kohlerba 0:8a2cac9ba89e 95 case AFS_8G:
kohlerba 0:8a2cac9ba89e 96 aRes = 8.0/32768.0;
kohlerba 0:8a2cac9ba89e 97 break;
kohlerba 0:8a2cac9ba89e 98 case AFS_16G:
kohlerba 0:8a2cac9ba89e 99 aRes = 16.0/32768.0;
kohlerba 0:8a2cac9ba89e 100 break;
kohlerba 0:8a2cac9ba89e 101 }
kohlerba 0:8a2cac9ba89e 102 }
kohlerba 0:8a2cac9ba89e 103
kohlerba 0:8a2cac9ba89e 104 void mpu6050::readAccelData(int16_t * destination)
kohlerba 0:8a2cac9ba89e 105 {
kohlerba 0:8a2cac9ba89e 106 uint8_t rawData[6]; // x/y/z accel register data stored here
kohlerba 0:8a2cac9ba89e 107 readBytes(MPU6050_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array
kohlerba 0:8a2cac9ba89e 108 destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
kohlerba 0:8a2cac9ba89e 109 destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
kohlerba 0:8a2cac9ba89e 110 destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
kohlerba 0:8a2cac9ba89e 111 }
kohlerba 0:8a2cac9ba89e 112
kohlerba 0:8a2cac9ba89e 113 void mpu6050::readGyroData(int16_t * destination)
kohlerba 0:8a2cac9ba89e 114 {
kohlerba 0:8a2cac9ba89e 115 uint8_t rawData[6]; // x/y/z gyro register data stored here
kohlerba 0:8a2cac9ba89e 116 readBytes(MPU6050_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array
kohlerba 0:8a2cac9ba89e 117 destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
kohlerba 0:8a2cac9ba89e 118 destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
kohlerba 0:8a2cac9ba89e 119 destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
kohlerba 0:8a2cac9ba89e 120 }
kohlerba 0:8a2cac9ba89e 121
kohlerba 0:8a2cac9ba89e 122 int16_t mpu6050::readTempData()
kohlerba 0:8a2cac9ba89e 123 {
kohlerba 0:8a2cac9ba89e 124 uint8_t rawData[2]; // x/y/z gyro register data stored here
kohlerba 0:8a2cac9ba89e 125 readBytes(MPU6050_ADDRESS, TEMP_OUT_H, 2, &rawData[0]); // Read the two raw data registers sequentially into data array
kohlerba 0:8a2cac9ba89e 126 return (int16_t)(((int16_t)rawData[0]) << 8 | rawData[1]) ; // Turn the MSB and LSB into a 16-bit value
kohlerba 0:8a2cac9ba89e 127 }
kohlerba 0:8a2cac9ba89e 128
kohlerba 0:8a2cac9ba89e 129 // Configure the motion detection control for low power accelerometer mode
kohlerba 0:8a2cac9ba89e 130 void mpu6050::lowPowerAccelOnly()
kohlerba 0:8a2cac9ba89e 131 {
kohlerba 0:8a2cac9ba89e 132
kohlerba 0:8a2cac9ba89e 133 // The sensor has a high-pass filter necessary to invoke to allow the sensor motion detection algorithms work properly
kohlerba 0:8a2cac9ba89e 134 // Motion detection occurs on free-fall (acceleration below a threshold for some time for all axes), motion (acceleration
kohlerba 0:8a2cac9ba89e 135 // above a threshold for some time on at least one axis), and zero-motion toggle (acceleration on each axis less than a
kohlerba 0:8a2cac9ba89e 136 // threshold for some time sets this flag, motion above the threshold turns it off). The high-pass filter takes gravity out
kohlerba 0:8a2cac9ba89e 137 // consideration for these threshold evaluations; otherwise, the flags would be set all the time!
kohlerba 0:8a2cac9ba89e 138
kohlerba 0:8a2cac9ba89e 139 uint8_t c = readByte(MPU6050_ADDRESS, PWR_MGMT_1);
kohlerba 0:8a2cac9ba89e 140 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c & ~0x30); // Clear sleep and cycle bits [5:6]
kohlerba 0:8a2cac9ba89e 141 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c | 0x30); // Set sleep and cycle bits [5:6] to zero to make sure accelerometer is running
kohlerba 0:8a2cac9ba89e 142
kohlerba 0:8a2cac9ba89e 143 c = readByte(MPU6050_ADDRESS, PWR_MGMT_2);
kohlerba 0:8a2cac9ba89e 144 writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c & ~0x38); // Clear standby XA, YA, and ZA bits [3:5]
kohlerba 0:8a2cac9ba89e 145 writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c | 0x00); // Set XA, YA, and ZA bits [3:5] to zero to make sure accelerometer is running
kohlerba 0:8a2cac9ba89e 146
kohlerba 0:8a2cac9ba89e 147 c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
kohlerba 0:8a2cac9ba89e 148 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x07); // Clear high-pass filter bits [2:0]
kohlerba 0:8a2cac9ba89e 149 // 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
kohlerba 0:8a2cac9ba89e 150 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c | 0x00); // Set ACCEL_HPF to 0; reset mode disbaling high-pass filter
kohlerba 0:8a2cac9ba89e 151
kohlerba 0:8a2cac9ba89e 152 c = readByte(MPU6050_ADDRESS, CONFIG);
kohlerba 0:8a2cac9ba89e 153 writeByte(MPU6050_ADDRESS, CONFIG, c & ~0x07); // Clear low-pass filter bits [2:0]
kohlerba 0:8a2cac9ba89e 154 writeByte(MPU6050_ADDRESS, CONFIG, c | 0x00); // Set DLPD_CFG to 0; 260 Hz bandwidth, 1 kHz rate
kohlerba 0:8a2cac9ba89e 155
kohlerba 0:8a2cac9ba89e 156 c = readByte(MPU6050_ADDRESS, INT_ENABLE);
kohlerba 0:8a2cac9ba89e 157 writeByte(MPU6050_ADDRESS, INT_ENABLE, c & ~0xFF); // Clear all interrupts
kohlerba 0:8a2cac9ba89e 158 writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x40); // Enable motion threshold (bits 5) interrupt only
kohlerba 0:8a2cac9ba89e 159
kohlerba 0:8a2cac9ba89e 160 // Motion detection interrupt requires the absolute value of any axis to lie above the detection threshold
kohlerba 0:8a2cac9ba89e 161 // for at least the counter duration
kohlerba 0:8a2cac9ba89e 162 writeByte(MPU6050_ADDRESS, MOT_THR, 0x80); // Set motion detection to 0.256 g; LSB = 2 mg
kohlerba 0:8a2cac9ba89e 163 writeByte(MPU6050_ADDRESS, MOT_DUR, 0x01); // Set motion detect duration to 1 ms; LSB is 1 ms @ 1 kHz rate
kohlerba 0:8a2cac9ba89e 164
kohlerba 0:8a2cac9ba89e 165 wait(0.1); // Add delay for accumulation of samples
kohlerba 0:8a2cac9ba89e 166
kohlerba 0:8a2cac9ba89e 167 c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
kohlerba 0:8a2cac9ba89e 168 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x07); // Clear high-pass filter bits [2:0]
kohlerba 0:8a2cac9ba89e 169 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c | 0x07); // Set ACCEL_HPF to 7; hold the initial accleration value as a referance
kohlerba 0:8a2cac9ba89e 170
kohlerba 0:8a2cac9ba89e 171 c = readByte(MPU6050_ADDRESS, PWR_MGMT_2);
kohlerba 0:8a2cac9ba89e 172 writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c & ~0xC7); // Clear standby XA, YA, and ZA bits [3:5] and LP_WAKE_CTRL bits [6:7]
kohlerba 0:8a2cac9ba89e 173 writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c | 0x47); // Set wakeup frequency to 5 Hz, and disable XG, YG, and ZG gyros (bits [0:2])
kohlerba 0:8a2cac9ba89e 174
kohlerba 0:8a2cac9ba89e 175 c = readByte(MPU6050_ADDRESS, PWR_MGMT_1);
kohlerba 0:8a2cac9ba89e 176 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c & ~0x20); // Clear sleep and cycle bit 5
kohlerba 0:8a2cac9ba89e 177 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c | 0x20); // Set cycle bit 5 to begin low power accelerometer motion interrupts
kohlerba 0:8a2cac9ba89e 178
kohlerba 0:8a2cac9ba89e 179 }
kohlerba 0:8a2cac9ba89e 180
kohlerba 0:8a2cac9ba89e 181
kohlerba 0:8a2cac9ba89e 182 void mpu6050::reset() {
kohlerba 0:8a2cac9ba89e 183 // reset device
kohlerba 0:8a2cac9ba89e 184 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
kohlerba 0:8a2cac9ba89e 185 wait(0.1);
kohlerba 0:8a2cac9ba89e 186 }
kohlerba 0:8a2cac9ba89e 187
kohlerba 0:8a2cac9ba89e 188
kohlerba 0:8a2cac9ba89e 189 void mpu6050::init()
kohlerba 0:8a2cac9ba89e 190 {
kohlerba 0:8a2cac9ba89e 191 // Initialize MPU6050 device
kohlerba 0:8a2cac9ba89e 192 // wake up device
kohlerba 0:8a2cac9ba89e 193 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00); // Clear sleep mode bit (6), enable all sensors
kohlerba 0:8a2cac9ba89e 194 wait(0.1); // Delay 100 ms for PLL to get established on x-axis gyro; should check for PLL ready interrupt
kohlerba 0:8a2cac9ba89e 195
kohlerba 0:8a2cac9ba89e 196 // get stable time source
kohlerba 0:8a2cac9ba89e 197 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01); // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001
kohlerba 0:8a2cac9ba89e 198
kohlerba 0:8a2cac9ba89e 199 // Configure Gyro and Accelerometer
kohlerba 0:8a2cac9ba89e 200 // Disable FSYNC and set accelerometer and gyro bandwidth to 44 and 42 Hz, respectively;
kohlerba 0:8a2cac9ba89e 201 // DLPF_CFG = bits 2:0 = 010; this sets the sample rate at 1 kHz for both
kohlerba 0:8a2cac9ba89e 202 // Maximum delay is 4.9 ms which is just over a 200 Hz maximum rate
kohlerba 0:8a2cac9ba89e 203 writeByte(MPU6050_ADDRESS, CONFIG, 0x03);
kohlerba 0:8a2cac9ba89e 204
kohlerba 0:8a2cac9ba89e 205 // Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV)
kohlerba 0:8a2cac9ba89e 206 writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x04); // Use a 200 Hz rate; the same rate set in CONFIG above
kohlerba 0:8a2cac9ba89e 207
kohlerba 0:8a2cac9ba89e 208 // Set gyroscope full scale range
kohlerba 0:8a2cac9ba89e 209 // Range selects FS_SEL and AFS_SEL are 0 - 3, so 2-bit values are left-shifted into positions 4:3
kohlerba 0:8a2cac9ba89e 210 uint8_t c = readByte(MPU6050_ADDRESS, GYRO_CONFIG);
kohlerba 0:8a2cac9ba89e 211 writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c & ~0xE0); // Clear self-test bits [7:5]
kohlerba 0:8a2cac9ba89e 212 writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
kohlerba 0:8a2cac9ba89e 213 writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c | Gscale << 3); // Set full scale range for the gyro
kohlerba 0:8a2cac9ba89e 214
kohlerba 0:8a2cac9ba89e 215 // Set accelerometer configuration
kohlerba 0:8a2cac9ba89e 216 c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
kohlerba 0:8a2cac9ba89e 217 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0xE0); // Clear self-test bits [7:5]
kohlerba 0:8a2cac9ba89e 218 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
kohlerba 0:8a2cac9ba89e 219 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c | Ascale << 3); // Set full scale range for the accelerometer
kohlerba 0:8a2cac9ba89e 220
kohlerba 0:8a2cac9ba89e 221 // Configure Interrupts and Bypass Enable
kohlerba 0:8a2cac9ba89e 222 // Set interrupt pin active high, push-pull, and clear on read of INT_STATUS, enable I2C_BYPASS_EN so additional chips
kohlerba 0:8a2cac9ba89e 223 // can join the I2C bus and all can be controlled by the Arduino as master
kohlerba 0:8a2cac9ba89e 224 writeByte(MPU6050_ADDRESS, INT_PIN_CFG, 0x22);
kohlerba 0:8a2cac9ba89e 225 writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x01); // Enable data ready (bit 0) interrupt
kohlerba 0:8a2cac9ba89e 226 }
kohlerba 0:8a2cac9ba89e 227
kohlerba 0:8a2cac9ba89e 228 // Function which accumulates gyro and accelerometer data after device initialization. It calculates the average
kohlerba 0:8a2cac9ba89e 229 // of the at-rest readings and then loads the resulting offsets into accelerometer and gyro bias registers.
kohlerba 0:8a2cac9ba89e 230 void mpu6050::calibrate(float * dest1, float * dest2)
kohlerba 0:8a2cac9ba89e 231 {
kohlerba 0:8a2cac9ba89e 232 uint8_t data[12]; // data array to hold accelerometer and gyro x, y, z, data
kohlerba 0:8a2cac9ba89e 233 uint16_t ii, packet_count, fifo_count;
kohlerba 0:8a2cac9ba89e 234 int32_t gyro_bias[3] = {0, 0, 0}, accel_bias[3] = {0, 0, 0};
kohlerba 0:8a2cac9ba89e 235
kohlerba 0:8a2cac9ba89e 236 // reset device, reset all registers, clear gyro and accelerometer bias registers
kohlerba 0:8a2cac9ba89e 237 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
kohlerba 0:8a2cac9ba89e 238 wait(0.1);
kohlerba 0:8a2cac9ba89e 239
kohlerba 0:8a2cac9ba89e 240 // get stable time source
kohlerba 0:8a2cac9ba89e 241 // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001
kohlerba 0:8a2cac9ba89e 242 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01);
kohlerba 0:8a2cac9ba89e 243 writeByte(MPU6050_ADDRESS, PWR_MGMT_2, 0x00);
kohlerba 0:8a2cac9ba89e 244 wait(0.2);
kohlerba 0:8a2cac9ba89e 245
kohlerba 0:8a2cac9ba89e 246 // Configure device for bias calculation
kohlerba 0:8a2cac9ba89e 247 writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x00); // Disable all interrupts
kohlerba 0:8a2cac9ba89e 248 writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00); // Disable FIFO
kohlerba 0:8a2cac9ba89e 249 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00); // Turn on internal clock source
kohlerba 0:8a2cac9ba89e 250 writeByte(MPU6050_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master
kohlerba 0:8a2cac9ba89e 251 writeByte(MPU6050_ADDRESS, USER_CTRL, 0x00); // Disable FIFO and I2C master modes
kohlerba 0:8a2cac9ba89e 252 writeByte(MPU6050_ADDRESS, USER_CTRL, 0x0C); // Reset FIFO and DMP
kohlerba 0:8a2cac9ba89e 253 wait(0.015);
kohlerba 0:8a2cac9ba89e 254
kohlerba 0:8a2cac9ba89e 255 // Configure MPU6050 gyro and accelerometer for bias calculation
kohlerba 0:8a2cac9ba89e 256 writeByte(MPU6050_ADDRESS, CONFIG, 0x01); // Set low-pass filter to 188 Hz
kohlerba 0:8a2cac9ba89e 257 writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x00); // Set sample rate to 1 kHz
kohlerba 0:8a2cac9ba89e 258 writeByte(MPU6050_ADDRESS, GYRO_CONFIG, 0x00); // Set gyro full-scale to 250 degrees per second, maximum sensitivity
kohlerba 0:8a2cac9ba89e 259 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity
kohlerba 0:8a2cac9ba89e 260
kohlerba 0:8a2cac9ba89e 261 uint16_t gyrosensitivity = 131; // = 131 LSB/degrees/sec
kohlerba 0:8a2cac9ba89e 262 uint16_t accelsensitivity = 16384; // = 16384 LSB/g
kohlerba 0:8a2cac9ba89e 263
kohlerba 0:8a2cac9ba89e 264 // Configure FIFO to capture accelerometer and gyro data for bias calculation
kohlerba 0:8a2cac9ba89e 265 writeByte(MPU6050_ADDRESS, USER_CTRL, 0x40); // Enable FIFO
kohlerba 0:8a2cac9ba89e 266 writeByte(MPU6050_ADDRESS, FIFO_EN, 0x78); // Enable gyro and accelerometer sensors for FIFO (max size 1024 bytes in MPU-6050)
kohlerba 0:8a2cac9ba89e 267 wait(0.08); // accumulate 80 samples in 80 milliseconds = 960 bytes
kohlerba 0:8a2cac9ba89e 268
kohlerba 0:8a2cac9ba89e 269 // At end of sample accumulation, turn off FIFO sensor read
kohlerba 0:8a2cac9ba89e 270 writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00); // Disable gyro and accelerometer sensors for FIFO
kohlerba 0:8a2cac9ba89e 271 readBytes(MPU6050_ADDRESS, FIFO_COUNTH, 2, &data[0]); // read FIFO sample count
kohlerba 0:8a2cac9ba89e 272 fifo_count = ((uint16_t)data[0] << 8) | data[1];
kohlerba 0:8a2cac9ba89e 273 packet_count = fifo_count/12;// How many sets of full gyro and accelerometer data for averaging
kohlerba 0:8a2cac9ba89e 274
kohlerba 0:8a2cac9ba89e 275 for (ii = 0; ii < packet_count; ii++) {
kohlerba 0:8a2cac9ba89e 276 int16_t accel_temp[3] = {0, 0, 0}, gyro_temp[3] = {0, 0, 0};
kohlerba 0:8a2cac9ba89e 277 readBytes(MPU6050_ADDRESS, FIFO_R_W, 12, &data[0]); // read data for averaging
kohlerba 0:8a2cac9ba89e 278 accel_temp[0] = (int16_t) (((int16_t)data[0] << 8) | data[1] ) ; // Form signed 16-bit integer for each sample in FIFO
kohlerba 0:8a2cac9ba89e 279 accel_temp[1] = (int16_t) (((int16_t)data[2] << 8) | data[3] ) ;
kohlerba 0:8a2cac9ba89e 280 accel_temp[2] = (int16_t) (((int16_t)data[4] << 8) | data[5] ) ;
kohlerba 0:8a2cac9ba89e 281 gyro_temp[0] = (int16_t) (((int16_t)data[6] << 8) | data[7] ) ;
kohlerba 0:8a2cac9ba89e 282 gyro_temp[1] = (int16_t) (((int16_t)data[8] << 8) | data[9] ) ;
kohlerba 0:8a2cac9ba89e 283 gyro_temp[2] = (int16_t) (((int16_t)data[10] << 8) | data[11]) ;
kohlerba 0:8a2cac9ba89e 284
kohlerba 0:8a2cac9ba89e 285 accel_bias[0] += (int32_t) accel_temp[0]; // Sum individual signed 16-bit biases to get accumulated signed 32-bit biases
kohlerba 0:8a2cac9ba89e 286 accel_bias[1] += (int32_t) accel_temp[1];
kohlerba 0:8a2cac9ba89e 287 accel_bias[2] += (int32_t) accel_temp[2];
kohlerba 0:8a2cac9ba89e 288 gyro_bias[0] += (int32_t) gyro_temp[0];
kohlerba 0:8a2cac9ba89e 289 gyro_bias[1] += (int32_t) gyro_temp[1];
kohlerba 0:8a2cac9ba89e 290 gyro_bias[2] += (int32_t) gyro_temp[2];
kohlerba 0:8a2cac9ba89e 291
kohlerba 0:8a2cac9ba89e 292 }
kohlerba 0:8a2cac9ba89e 293 accel_bias[0] /= (int32_t) packet_count; // Normalize sums to get average count biases
kohlerba 0:8a2cac9ba89e 294 accel_bias[1] /= (int32_t) packet_count;
kohlerba 0:8a2cac9ba89e 295 accel_bias[2] /= (int32_t) packet_count;
kohlerba 0:8a2cac9ba89e 296 gyro_bias[0] /= (int32_t) packet_count;
kohlerba 0:8a2cac9ba89e 297 gyro_bias[1] /= (int32_t) packet_count;
kohlerba 0:8a2cac9ba89e 298 gyro_bias[2] /= (int32_t) packet_count;
kohlerba 0:8a2cac9ba89e 299
kohlerba 0:8a2cac9ba89e 300 if(accel_bias[2] > 0L) {accel_bias[2] -= (int32_t) accelsensitivity;} // Remove gravity from the z-axis accelerometer bias calculation
kohlerba 0:8a2cac9ba89e 301 else {accel_bias[2] += (int32_t) accelsensitivity;}
kohlerba 0:8a2cac9ba89e 302
kohlerba 0:8a2cac9ba89e 303 // Construct the gyro biases for push to the hardware gyro bias registers, which are reset to zero upon device startup
kohlerba 0:8a2cac9ba89e 304 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
kohlerba 0:8a2cac9ba89e 305 data[1] = (-gyro_bias[0]/4) & 0xFF; // Biases are additive, so change sign on calculated average gyro biases
kohlerba 0:8a2cac9ba89e 306 data[2] = (-gyro_bias[1]/4 >> 8) & 0xFF;
kohlerba 0:8a2cac9ba89e 307 data[3] = (-gyro_bias[1]/4) & 0xFF;
kohlerba 0:8a2cac9ba89e 308 data[4] = (-gyro_bias[2]/4 >> 8) & 0xFF;
kohlerba 0:8a2cac9ba89e 309 data[5] = (-gyro_bias[2]/4) & 0xFF;
kohlerba 0:8a2cac9ba89e 310
kohlerba 0:8a2cac9ba89e 311 // Push gyro biases to hardware registers
kohlerba 0:8a2cac9ba89e 312 writeByte(MPU6050_ADDRESS, XG_OFFS_USRH, data[0]);
kohlerba 0:8a2cac9ba89e 313 writeByte(MPU6050_ADDRESS, XG_OFFS_USRL, data[1]);
kohlerba 0:8a2cac9ba89e 314 writeByte(MPU6050_ADDRESS, YG_OFFS_USRH, data[2]);
kohlerba 0:8a2cac9ba89e 315 writeByte(MPU6050_ADDRESS, YG_OFFS_USRL, data[3]);
kohlerba 0:8a2cac9ba89e 316 writeByte(MPU6050_ADDRESS, ZG_OFFS_USRH, data[4]);
kohlerba 0:8a2cac9ba89e 317 writeByte(MPU6050_ADDRESS, ZG_OFFS_USRL, data[5]);
kohlerba 0:8a2cac9ba89e 318
kohlerba 0:8a2cac9ba89e 319 dest1[0] = (float) gyro_bias[0]/(float) gyrosensitivity; // construct gyro bias in deg/s for later manual subtraction
kohlerba 0:8a2cac9ba89e 320 dest1[1] = (float) gyro_bias[1]/(float) gyrosensitivity;
kohlerba 0:8a2cac9ba89e 321 dest1[2] = (float) gyro_bias[2]/(float) gyrosensitivity;
kohlerba 0:8a2cac9ba89e 322
kohlerba 0:8a2cac9ba89e 323 // Construct the accelerometer biases for push to the hardware accelerometer bias registers. These registers contain
kohlerba 0:8a2cac9ba89e 324 // factory trim values which must be added to the calculated accelerometer biases; on boot up these registers will hold
kohlerba 0:8a2cac9ba89e 325 // non-zero values. In addition, bit 0 of the lower byte must be preserved since it is used for temperature
kohlerba 0:8a2cac9ba89e 326 // compensation calculations. Accelerometer bias registers expect bias input as 2048 LSB per g, so that
kohlerba 0:8a2cac9ba89e 327 // the accelerometer biases calculated above must be divided by 8.
kohlerba 0:8a2cac9ba89e 328
kohlerba 0:8a2cac9ba89e 329 int32_t accel_bias_reg[3] = {0, 0, 0}; // A place to hold the factory accelerometer trim biases
kohlerba 0:8a2cac9ba89e 330 readBytes(MPU6050_ADDRESS, XA_OFFSET_H, 2, &data[0]); // Read factory accelerometer trim values
kohlerba 0:8a2cac9ba89e 331 accel_bias_reg[0] = (int16_t) ((int16_t)data[0] << 8) | data[1];
kohlerba 0:8a2cac9ba89e 332 readBytes(MPU6050_ADDRESS, YA_OFFSET_H, 2, &data[0]);
kohlerba 0:8a2cac9ba89e 333 accel_bias_reg[1] = (int16_t) ((int16_t)data[0] << 8) | data[1];
kohlerba 0:8a2cac9ba89e 334 readBytes(MPU6050_ADDRESS, ZA_OFFSET_H, 2, &data[0]);
kohlerba 0:8a2cac9ba89e 335 accel_bias_reg[2] = (int16_t) ((int16_t)data[0] << 8) | data[1];
kohlerba 0:8a2cac9ba89e 336
kohlerba 0:8a2cac9ba89e 337 uint32_t mask = 1uL; // Define mask for temperature compensation bit 0 of lower byte of accelerometer bias registers
kohlerba 0:8a2cac9ba89e 338 uint8_t mask_bit[3] = {0, 0, 0}; // Define array to hold mask bit for each accelerometer bias axis
kohlerba 0:8a2cac9ba89e 339
kohlerba 0:8a2cac9ba89e 340 for(ii = 0; ii < 3; ii++) {
kohlerba 0:8a2cac9ba89e 341 if(accel_bias_reg[ii] & mask) mask_bit[ii] = 0x01; // If temperature compensation bit is set, record that fact in mask_bit
kohlerba 0:8a2cac9ba89e 342 }
kohlerba 0:8a2cac9ba89e 343
kohlerba 0:8a2cac9ba89e 344 // Construct total accelerometer bias, including calculated average accelerometer bias from above
kohlerba 0:8a2cac9ba89e 345 accel_bias_reg[0] -= (accel_bias[0]/8); // Subtract calculated averaged accelerometer bias scaled to 2048 LSB/g (16 g full scale)
kohlerba 0:8a2cac9ba89e 346 accel_bias_reg[1] -= (accel_bias[1]/8);
kohlerba 0:8a2cac9ba89e 347 accel_bias_reg[2] -= (accel_bias[2]/8);
kohlerba 0:8a2cac9ba89e 348
kohlerba 0:8a2cac9ba89e 349 data[0] = (accel_bias_reg[0] >> 8) & 0xFF;
kohlerba 0:8a2cac9ba89e 350 data[1] = (accel_bias_reg[0]) & 0xFF;
kohlerba 0:8a2cac9ba89e 351 data[1] = data[1] | mask_bit[0]; // preserve temperature compensation bit when writing back to accelerometer bias registers
kohlerba 0:8a2cac9ba89e 352 data[2] = (accel_bias_reg[1] >> 8) & 0xFF;
kohlerba 0:8a2cac9ba89e 353 data[3] = (accel_bias_reg[1]) & 0xFF;
kohlerba 0:8a2cac9ba89e 354 data[3] = data[3] | mask_bit[1]; // preserve temperature compensation bit when writing back to accelerometer bias registers
kohlerba 0:8a2cac9ba89e 355 data[4] = (accel_bias_reg[2] >> 8) & 0xFF;
kohlerba 0:8a2cac9ba89e 356 data[5] = (accel_bias_reg[2]) & 0xFF;
kohlerba 0:8a2cac9ba89e 357 data[5] = data[5] | mask_bit[2]; // preserve temperature compensation bit when writing back to accelerometer bias registers
kohlerba 0:8a2cac9ba89e 358
kohlerba 0:8a2cac9ba89e 359 // Push accelerometer biases to hardware registers
kohlerba 0:8a2cac9ba89e 360 // writeByte(MPU6050_ADDRESS, XA_OFFSET_H, data[0]);
kohlerba 0:8a2cac9ba89e 361 // writeByte(MPU6050_ADDRESS, XA_OFFSET_L_TC, data[1]);
kohlerba 0:8a2cac9ba89e 362 // writeByte(MPU6050_ADDRESS, YA_OFFSET_H, data[2]);
kohlerba 0:8a2cac9ba89e 363 // writeByte(MPU6050_ADDRESS, YA_OFFSET_L_TC, data[3]);
kohlerba 0:8a2cac9ba89e 364 // writeByte(MPU6050_ADDRESS, ZA_OFFSET_H, data[4]);
kohlerba 0:8a2cac9ba89e 365 // writeByte(MPU6050_ADDRESS, ZA_OFFSET_L_TC, data[5]);
kohlerba 0:8a2cac9ba89e 366
kohlerba 0:8a2cac9ba89e 367 // Output scaled accelerometer biases for manual subtraction in the main program
kohlerba 0:8a2cac9ba89e 368 dest2[0] = (float)accel_bias[0]/(float)accelsensitivity;
kohlerba 0:8a2cac9ba89e 369 dest2[1] = (float)accel_bias[1]/(float)accelsensitivity;
kohlerba 0:8a2cac9ba89e 370 dest2[2] = (float)accel_bias[2]/(float)accelsensitivity;
kohlerba 0:8a2cac9ba89e 371 }
kohlerba 0:8a2cac9ba89e 372
kohlerba 0:8a2cac9ba89e 373
kohlerba 0:8a2cac9ba89e 374 // Accelerometer and gyroscope self test; check calibration wrt factory settings
kohlerba 0:8a2cac9ba89e 375 void mpu6050::selfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass
kohlerba 0:8a2cac9ba89e 376 {
kohlerba 0:8a2cac9ba89e 377 uint8_t rawData[4] = {0, 0, 0, 0};
kohlerba 0:8a2cac9ba89e 378 uint8_t selfTest[6];
kohlerba 0:8a2cac9ba89e 379 float factoryTrim[6];
kohlerba 0:8a2cac9ba89e 380
kohlerba 0:8a2cac9ba89e 381 // Configure the accelerometer for self-test
kohlerba 0:8a2cac9ba89e 382 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0xF0); // Enable self test on all three axes and set accelerometer range to +/- 8 g
kohlerba 0:8a2cac9ba89e 383 writeByte(MPU6050_ADDRESS, GYRO_CONFIG, 0xE0); // Enable self test on all three axes and set gyro range to +/- 250 degrees/s
kohlerba 0:8a2cac9ba89e 384 wait(0.25); // Delay a while to let the device execute the self-test
kohlerba 0:8a2cac9ba89e 385 rawData[0] = readByte(MPU6050_ADDRESS, SELF_TEST_X); // X-axis self-test results
kohlerba 0:8a2cac9ba89e 386 rawData[1] = readByte(MPU6050_ADDRESS, SELF_TEST_Y); // Y-axis self-test results
kohlerba 0:8a2cac9ba89e 387 rawData[2] = readByte(MPU6050_ADDRESS, SELF_TEST_Z); // Z-axis self-test results
kohlerba 0:8a2cac9ba89e 388 rawData[3] = readByte(MPU6050_ADDRESS, SELF_TEST_A); // Mixed-axis self-test results
kohlerba 0:8a2cac9ba89e 389 // Extract the acceleration test results first
kohlerba 0:8a2cac9ba89e 390 selfTest[0] = (rawData[0] >> 3) | (rawData[3] & 0x30) >> 4 ; // XA_TEST result is a five-bit unsigned integer
kohlerba 0:8a2cac9ba89e 391 selfTest[1] = (rawData[1] >> 3) | (rawData[3] & 0x0C) >> 4 ; // YA_TEST result is a five-bit unsigned integer
kohlerba 0:8a2cac9ba89e 392 selfTest[2] = (rawData[2] >> 3) | (rawData[3] & 0x03) >> 4 ; // ZA_TEST result is a five-bit unsigned integer
kohlerba 0:8a2cac9ba89e 393 // Extract the gyration test results first
kohlerba 0:8a2cac9ba89e 394 selfTest[3] = rawData[0] & 0x1F ; // XG_TEST result is a five-bit unsigned integer
kohlerba 0:8a2cac9ba89e 395 selfTest[4] = rawData[1] & 0x1F ; // YG_TEST result is a five-bit unsigned integer
kohlerba 0:8a2cac9ba89e 396 selfTest[5] = rawData[2] & 0x1F ; // ZG_TEST result is a five-bit unsigned integer
kohlerba 0:8a2cac9ba89e 397 // Process results to allow final comparison with factory set values
kohlerba 0:8a2cac9ba89e 398 factoryTrim[0] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[0] - 1.0f)/30.0f))); // FT[Xa] factory trim calculation
kohlerba 0:8a2cac9ba89e 399 factoryTrim[1] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[1] - 1.0f)/30.0f))); // FT[Ya] factory trim calculation
kohlerba 0:8a2cac9ba89e 400 factoryTrim[2] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[2] - 1.0f)/30.0f))); // FT[Za] factory trim calculation
kohlerba 0:8a2cac9ba89e 401 factoryTrim[3] = ( 25.0f*131.0f)*(pow( 1.046f , (selfTest[3] - 1.0f) )); // FT[Xg] factory trim calculation
kohlerba 0:8a2cac9ba89e 402 factoryTrim[4] = (-25.0f*131.0f)*(pow( 1.046f , (selfTest[4] - 1.0f) )); // FT[Yg] factory trim calculation
kohlerba 0:8a2cac9ba89e 403 factoryTrim[5] = ( 25.0f*131.0f)*(pow( 1.046f , (selfTest[5] - 1.0f) )); // FT[Zg] factory trim calculation
kohlerba 0:8a2cac9ba89e 404
kohlerba 0:8a2cac9ba89e 405 // Output self-test results and factory trim calculation if desired
kohlerba 0:8a2cac9ba89e 406 // Serial.println(selfTest[0]); Serial.println(selfTest[1]); Serial.println(selfTest[2]);
kohlerba 0:8a2cac9ba89e 407 // Serial.println(selfTest[3]); Serial.println(selfTest[4]); Serial.println(selfTest[5]);
kohlerba 0:8a2cac9ba89e 408 // Serial.println(factoryTrim[0]); Serial.println(factoryTrim[1]); Serial.println(factoryTrim[2]);
kohlerba 0:8a2cac9ba89e 409 // Serial.println(factoryTrim[3]); Serial.println(factoryTrim[4]); Serial.println(factoryTrim[5]);
kohlerba 0:8a2cac9ba89e 410
kohlerba 0:8a2cac9ba89e 411 // Report results as a ratio of (STR - FT)/FT; the change from Factory Trim of the Self-Test Response
kohlerba 0:8a2cac9ba89e 412 // To get to percent, must multiply by 100 and subtract result from 100
kohlerba 0:8a2cac9ba89e 413 for (int i = 0; i < 6; i++) {
kohlerba 0:8a2cac9ba89e 414 destination[i] = 100.0f + 100.0f*(selfTest[i] - factoryTrim[i])/factoryTrim[i]; // Report percent differences
kohlerba 0:8a2cac9ba89e 415 }
kohlerba 0:8a2cac9ba89e 416
kohlerba 0:8a2cac9ba89e 417 }
kohlerba 0:8a2cac9ba89e 418
kohlerba 0:8a2cac9ba89e 419
kohlerba 0:8a2cac9ba89e 420 // Implementation of Sebastian Madgwick's "...efficient orientation filter for... inertial/magnetic sensor arrays"
kohlerba 0:8a2cac9ba89e 421 // (see http://www.x-io.co.uk/category/open-source/ for examples and more details)
kohlerba 0:8a2cac9ba89e 422 // which fuses acceleration and rotation rate to produce a quaternion-based estimate of relative
kohlerba 0:8a2cac9ba89e 423 // device orientation -- which can be converted to yaw, pitch, and roll. Useful for stabilizing quadcopters, etc.
kohlerba 0:8a2cac9ba89e 424 // The performance of the orientation filter is at least as good as conventional Kalman-based filtering algorithms
kohlerba 0:8a2cac9ba89e 425 // but is much less computationally intensive---it can be performed on a 3.3 V Pro Mini operating at 8 MHz!
kohlerba 0:8a2cac9ba89e 426 void mpu6050::MadgwickQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz)
kohlerba 0:8a2cac9ba89e 427 {
kohlerba 0:8a2cac9ba89e 428 float q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3]; // short name local variable for readability
kohlerba 0:8a2cac9ba89e 429 float norm; // vector norm
kohlerba 0:8a2cac9ba89e 430 float f1, f2, f3; // objective funcyion elements
kohlerba 0:8a2cac9ba89e 431 float J_11or24, J_12or23, J_13or22, J_14or21, J_32, J_33; // objective function Jacobian elements
kohlerba 0:8a2cac9ba89e 432 float qDot1, qDot2, qDot3, qDot4;
kohlerba 0:8a2cac9ba89e 433 float hatDot1, hatDot2, hatDot3, hatDot4;
kohlerba 0:8a2cac9ba89e 434 float gerrx, gerry, gerrz, gbiasx, gbiasy, gbiasz; // gyro bias error
kohlerba 0:8a2cac9ba89e 435
kohlerba 0:8a2cac9ba89e 436 // Auxiliary variables to avoid repeated arithmetic
kohlerba 0:8a2cac9ba89e 437 float _halfq1 = 0.5f * q1;
kohlerba 0:8a2cac9ba89e 438 float _halfq2 = 0.5f * q2;
kohlerba 0:8a2cac9ba89e 439 float _halfq3 = 0.5f * q3;
kohlerba 0:8a2cac9ba89e 440 float _halfq4 = 0.5f * q4;
kohlerba 0:8a2cac9ba89e 441 float _2q1 = 2.0f * q1;
kohlerba 0:8a2cac9ba89e 442 float _2q2 = 2.0f * q2;
kohlerba 0:8a2cac9ba89e 443 float _2q3 = 2.0f * q3;
kohlerba 0:8a2cac9ba89e 444 float _2q4 = 2.0f * q4;
kohlerba 0:8a2cac9ba89e 445 // float _2q1q3 = 2.0f * q1 * q3;
kohlerba 0:8a2cac9ba89e 446 // float _2q3q4 = 2.0f * q3 * q4;
kohlerba 0:8a2cac9ba89e 447
kohlerba 0:8a2cac9ba89e 448 // Normalise accelerometer measurement
kohlerba 0:8a2cac9ba89e 449 norm = sqrt(ax * ax + ay * ay + az * az);
kohlerba 0:8a2cac9ba89e 450 if (norm == 0.0f) return; // handle NaN
kohlerba 0:8a2cac9ba89e 451 norm = 1.0f/norm;
kohlerba 0:8a2cac9ba89e 452 ax *= norm;
kohlerba 0:8a2cac9ba89e 453 ay *= norm;
kohlerba 0:8a2cac9ba89e 454 az *= norm;
kohlerba 0:8a2cac9ba89e 455
kohlerba 0:8a2cac9ba89e 456 // Compute the objective function and Jacobian
kohlerba 0:8a2cac9ba89e 457 f1 = _2q2 * q4 - _2q1 * q3 - ax;
kohlerba 0:8a2cac9ba89e 458 f2 = _2q1 * q2 + _2q3 * q4 - ay;
kohlerba 0:8a2cac9ba89e 459 f3 = 1.0f - _2q2 * q2 - _2q3 * q3 - az;
kohlerba 0:8a2cac9ba89e 460 J_11or24 = _2q3;
kohlerba 0:8a2cac9ba89e 461 J_12or23 = _2q4;
kohlerba 0:8a2cac9ba89e 462 J_13or22 = _2q1;
kohlerba 0:8a2cac9ba89e 463 J_14or21 = _2q2;
kohlerba 0:8a2cac9ba89e 464 J_32 = 2.0f * J_14or21;
kohlerba 0:8a2cac9ba89e 465 J_33 = 2.0f * J_11or24;
kohlerba 0:8a2cac9ba89e 466
kohlerba 0:8a2cac9ba89e 467 // Compute the gradient (matrix multiplication)
kohlerba 0:8a2cac9ba89e 468 hatDot1 = J_14or21 * f2 - J_11or24 * f1;
kohlerba 0:8a2cac9ba89e 469 hatDot2 = J_12or23 * f1 + J_13or22 * f2 - J_32 * f3;
kohlerba 0:8a2cac9ba89e 470 hatDot3 = J_12or23 * f2 - J_33 *f3 - J_13or22 * f1;
kohlerba 0:8a2cac9ba89e 471 hatDot4 = J_14or21 * f1 + J_11or24 * f2;
kohlerba 0:8a2cac9ba89e 472
kohlerba 0:8a2cac9ba89e 473 // Normalize the gradient
kohlerba 0:8a2cac9ba89e 474 norm = sqrt(hatDot1 * hatDot1 + hatDot2 * hatDot2 + hatDot3 * hatDot3 + hatDot4 * hatDot4);
kohlerba 0:8a2cac9ba89e 475 hatDot1 /= norm;
kohlerba 0:8a2cac9ba89e 476 hatDot2 /= norm;
kohlerba 0:8a2cac9ba89e 477 hatDot3 /= norm;
kohlerba 0:8a2cac9ba89e 478 hatDot4 /= norm;
kohlerba 0:8a2cac9ba89e 479
kohlerba 0:8a2cac9ba89e 480 // Compute estimated gyroscope biases
kohlerba 0:8a2cac9ba89e 481 gerrx = _2q1 * hatDot2 - _2q2 * hatDot1 - _2q3 * hatDot4 + _2q4 * hatDot3;
kohlerba 0:8a2cac9ba89e 482 gerry = _2q1 * hatDot3 + _2q2 * hatDot4 - _2q3 * hatDot1 - _2q4 * hatDot2;
kohlerba 0:8a2cac9ba89e 483 gerrz = _2q1 * hatDot4 - _2q2 * hatDot3 + _2q3 * hatDot2 - _2q4 * hatDot1;
kohlerba 0:8a2cac9ba89e 484
kohlerba 0:8a2cac9ba89e 485 // Compute and remove gyroscope biases
kohlerba 0:8a2cac9ba89e 486 gbiasx += gerrx * deltat * zeta;
kohlerba 0:8a2cac9ba89e 487 gbiasy += gerry * deltat * zeta;
kohlerba 0:8a2cac9ba89e 488 gbiasz += gerrz * deltat * zeta;
kohlerba 0:8a2cac9ba89e 489 // gx -= gbiasx;
kohlerba 0:8a2cac9ba89e 490 // gy -= gbiasy;
kohlerba 0:8a2cac9ba89e 491 // gz -= gbiasz;
kohlerba 0:8a2cac9ba89e 492
kohlerba 0:8a2cac9ba89e 493 // Compute the quaternion derivative
kohlerba 0:8a2cac9ba89e 494 qDot1 = -_halfq2 * gx - _halfq3 * gy - _halfq4 * gz;
kohlerba 0:8a2cac9ba89e 495 qDot2 = _halfq1 * gx + _halfq3 * gz - _halfq4 * gy;
kohlerba 0:8a2cac9ba89e 496 qDot3 = _halfq1 * gy - _halfq2 * gz + _halfq4 * gx;
kohlerba 0:8a2cac9ba89e 497 qDot4 = _halfq1 * gz + _halfq2 * gy - _halfq3 * gx;
kohlerba 0:8a2cac9ba89e 498
kohlerba 0:8a2cac9ba89e 499 // Compute then integrate estimated quaternion derivative
kohlerba 0:8a2cac9ba89e 500 q1 += (qDot1 -(beta * hatDot1)) * deltat;
kohlerba 0:8a2cac9ba89e 501 q2 += (qDot2 -(beta * hatDot2)) * deltat;
kohlerba 0:8a2cac9ba89e 502 q3 += (qDot3 -(beta * hatDot3)) * deltat;
kohlerba 0:8a2cac9ba89e 503 q4 += (qDot4 -(beta * hatDot4)) * deltat;
kohlerba 0:8a2cac9ba89e 504
kohlerba 0:8a2cac9ba89e 505 // Normalize the quaternion
kohlerba 0:8a2cac9ba89e 506 norm = sqrt(q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4); // normalise quaternion
kohlerba 0:8a2cac9ba89e 507 norm = 1.0f/norm;
kohlerba 0:8a2cac9ba89e 508 q[0] = q1 * norm;
kohlerba 0:8a2cac9ba89e 509 q[1] = q2 * norm;
kohlerba 0:8a2cac9ba89e 510 q[2] = q3 * norm;
kohlerba 0:8a2cac9ba89e 511 q[3] = q4 * norm;
kohlerba 0:8a2cac9ba89e 512
kohlerba 0:8a2cac9ba89e 513 }