航空研究会
usb実装中
Dependencies: mbed MPU6050_2 HMC5883L_2 SDFileSystem3
Diff: MPU9250/MPU9250.cpp
- Revision:
- 3:c18342e4fddd
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/MPU9250/MPU9250.cpp Wed Feb 06 11:49:05 2019 +0000
@@ -0,0 +1,901 @@
+#include "mbed.h"
+#include "math.h"
+#include "MPU9250.h"
+
+
+MPU9250::MPU9250(PinName sda, PinName scl, RawSerial* serial_p)
+ :
+ i2c_p(new I2C(sda,scl)),
+ i2c(*i2c_p),
+ pc_p(serial_p)
+{
+ initializeValue();
+}
+
+MPU9250::~MPU9250(){}
+
+
+/*---------- public function ----------*/
+bool MPU9250::Initialize(void){
+ uint8_t whoami;
+
+ i2c.frequency(400000); // use fast (400 kHz) I2C
+ timer.start();
+
+ whoami = Whoami_MPU9250();
+ pc_p->printf("I AM 0x%x\n\r", whoami); pc_p->printf("I SHOULD BE 0x71\n\r");
+
+ if(whoami == IAM_MPU9250){
+ resetMPU9250(); // Reset registers to default in preparation for device calibration
+ calibrateMPU9250(gyroBias, accelBias); // Calibrate gyro and accelerometers, load biases in bias registers
+ wait(1);
+
+ initMPU9250();
+ initAK8963(magCalibration);
+
+ pc_p->printf("Accelerometer full-scale range = %f g\n\r", 2.0f*(float)(1<<Ascale));
+ pc_p->printf("Gyroscope full-scale range = %f deg/s\n\r", 250.0f*(float)(1<<Gscale));
+
+ if(Mscale == 0) pc_p->printf("Magnetometer resolution = 14 bits\n\r");
+ if(Mscale == 1) pc_p->printf("Magnetometer resolution = 16 bits\n\r");
+ if(Mmode == 2) pc_p->printf("Magnetometer ODR = 8 Hz\n\r");
+ if(Mmode == 6) pc_p->printf("Magnetometer ODR = 100 Hz\n\r");
+
+ getAres();
+ getGres();
+ getMres();
+
+ pc_p->printf("mpu9250 initialized\r\n");
+ return true;
+ }else return false;
+}
+
+bool MPU9250::sensingAcGyMg(){
+ if(readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01) { // On interrupt, check if data ready interrupt
+ sensingAccel();
+ sensingGyro();
+ sensingMag();
+ return true;
+ }else return false;
+}
+
+
+void MPU9250::calculatePostureAngle(float degree[3]){
+ Now = timer.read_us();
+ deltat = (float)((Now - lastUpdate)/1000000.0f); // set integration time by time elapsed since last filter update
+ lastUpdate = Now;
+
+// if(lastUpdate - firstUpdate > 10000000.0f) {
+// beta = 0.04; // decrease filter gain after stabilized
+// zeta = 0.015; // increasey bias drift gain after stabilized
+// }
+
+ // Pass gyro rate as rad/s
+ MadgwickQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f, my, mx, mz);
+ MahonyQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f, my, mx, mz); //my, mx, mzになってるけどセンサの設置上の都合だろうか
+
+ // Define output variables from updated quaternion---these are Tait-Bryan angles, commonly used in aircraft orientation.
+ // In this coordinate system, the positive z-axis is down toward Earth.
+ // Yaw is the angle between Sensor x-axis and Earth magnetic North (or true North if corrected for local declination, looking down on the sensor positive yaw is counterclockwise.
+ // Pitch is angle between sensor x-axis and Earth ground plane, toward the Earth is positive, up toward the sky is negative.
+ // Roll is angle between sensor y-axis and Earth ground plane, y-axis up is positive roll.
+ // These arise from the definition of the homogeneous rotation matrix constructed from quaternions.
+ // Tait-Bryan angles as well as Euler angles are non-commutative; that is, the get the correct orientation the rotations must be
+ // applied in the correct order which for this configuration is yaw, pitch, and then roll.
+ // For more see http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles which has additional links.
+ translateQuaternionToDeg(q);
+ calibrateDegree();
+ degree[0] = roll;
+ degree[1] = pitch;
+ degree[2] = yaw;
+}
+
+
+float MPU9250::calculateYawByMg(){
+ transformCoordinateFromCompassToMPU();
+ lpmag[0] = LPGAIN_MAG *lpmag[0] + (1 - LPGAIN_MAG)*mx;
+ lpmag[1] = LPGAIN_MAG *lpmag[1] + (1 - LPGAIN_MAG)*my;
+ lpmag[2] = LPGAIN_MAG *lpmag[2] + (1 - LPGAIN_MAG)*mz;
+
+ float radroll = PI/180.0f * roll;
+ float radpitch = PI/180.0f * pitch;
+
+ return 180.0f/PI * atan2(lpmag[2]*sin(radpitch) - lpmag[1]*cos(radpitch),
+ lpmag[0]*cos(radroll) - lpmag[1]*sin(radroll)*sin(radpitch) + lpmag[2]*sin(radroll)*cos(radpitch));
+}
+
+
+// Accelerometer and gyroscope self test; check calibration wrt factory settings
+void MPU9250::MPU9250SelfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass
+{
+ uint8_t rawData[6] = {0, 0, 0, 0, 0, 0};
+ uint8_t selfTest[6];
+ int16_t gAvg[3], aAvg[3], aSTAvg[3], gSTAvg[3];
+ float factoryTrim[6];
+ uint8_t FS = 0;
+
+ writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x00); // Set gyro sample rate to 1 kHz
+ writeByte(MPU9250_ADDRESS, CONFIG, 0x02); // Set gyro sample rate to 1 kHz and DLPF to 92 Hz
+ writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 1<<FS); // Set full scale range for the gyro to 250 dps
+ writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, 0x02); // Set accelerometer rate to 1 kHz and bandwidth to 92 Hz
+ writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 1<<FS); // Set full scale range for the accelerometer to 2 g
+
+ for( int ii = 0; ii < 200; ii++) { // get average current values of gyro and acclerometer
+ readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array
+ aAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
+ aAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
+ aAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
+
+ readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array
+ gAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
+ gAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
+ gAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
+ }
+
+ for (int ii =0; ii < 3; ii++) { // Get average of 200 values and store as average current readings
+ aAvg[ii] /= 200;
+ gAvg[ii] /= 200;
+ }
+
+ // Configure the accelerometer for self-test
+ writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 0xE0); // Enable self test on all three axes and set accelerometer range to +/- 2 g
+ writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 0xE0); // Enable self test on all three axes and set gyro range to +/- 250 degrees/s
+ //delay(55); // Delay a while to let the device stabilize
+
+ for( int ii = 0; ii < 200; ii++) { // get average self-test values of gyro and acclerometer
+ readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array
+ aSTAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
+ aSTAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
+ aSTAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
+
+ readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array
+ gSTAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
+ gSTAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
+ gSTAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
+ }
+
+ for (int ii =0; ii < 3; ii++) { // Get average of 200 values and store as average self-test readings
+ aSTAvg[ii] /= 200;
+ gSTAvg[ii] /= 200;
+ }
+
+ // Configure the gyro and accelerometer for normal operation
+ writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 0x00);
+ writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 0x00);
+ //delay(45); // Delay a while to let the device stabilize
+
+ // Retrieve accelerometer and gyro factory Self-Test Code from USR_Reg
+ selfTest[0] = readByte(MPU9250_ADDRESS, SELF_TEST_X_ACCEL); // X-axis accel self-test results
+ selfTest[1] = readByte(MPU9250_ADDRESS, SELF_TEST_Y_ACCEL); // Y-axis accel self-test results
+ selfTest[2] = readByte(MPU9250_ADDRESS, SELF_TEST_Z_ACCEL); // Z-axis accel self-test results
+ selfTest[3] = readByte(MPU9250_ADDRESS, SELF_TEST_X_GYRO); // X-axis gyro self-test results
+ selfTest[4] = readByte(MPU9250_ADDRESS, SELF_TEST_Y_GYRO); // Y-axis gyro self-test results
+ selfTest[5] = readByte(MPU9250_ADDRESS, SELF_TEST_Z_GYRO); // Z-axis gyro self-test results
+
+ // Retrieve factory self-test value from self-test code reads
+ factoryTrim[0] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[0] - 1.0) )); // FT[Xa] factory trim calculation
+ factoryTrim[1] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[1] - 1.0) )); // FT[Ya] factory trim calculation
+ factoryTrim[2] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[2] - 1.0) )); // FT[Za] factory trim calculation
+ factoryTrim[3] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[3] - 1.0) )); // FT[Xg] factory trim calculation
+ factoryTrim[4] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[4] - 1.0) )); // FT[Yg] factory trim calculation
+ factoryTrim[5] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[5] - 1.0) )); // FT[Zg] factory trim calculation
+
+ // Report results as a ratio of (STR - FT)/FT; the change from Factory Trim of the Self-Test Response
+ // To get percent, must multiply by 100
+ for (int i = 0; i < 3; i++) {
+ destination[i] = 100.0*((float)(aSTAvg[i] - aAvg[i]))/factoryTrim[i]; // Report percent differences
+ destination[i+3] = 100.0*((float)(gSTAvg[i] - gAvg[i]))/factoryTrim[i+3]; // Report percent differences
+ }
+}
+
+void MPU9250::pickupAccel(float accel[3]){
+ sensingAccel();
+ accel[0] = ax;
+ accel[1] = ay;
+ accel[2] = az;
+}
+
+void MPU9250::pickupGyro(float gyro[3]){
+ sensingGyro();
+ gyro[0] = gx;
+ gyro[1] = gy;
+ gyro[2] = gz;
+}
+
+void MPU9250::pickupMag(float mag[3]){
+ sensingMag();
+ mag[0] = mx;
+ mag[1] = my;
+ mag[2] = mz;
+}
+
+float MPU9250::pickupTemp(void){
+ sensingTemp();
+ return temperature;
+}
+
+void MPU9250::displayAccel(void){
+ pc_p->printf("ax = %f", 1000*ax);
+ pc_p->printf(" ay = %f", 1000*ay);
+ pc_p->printf(" az = %f mg\n\r", 1000*az);
+}
+
+void MPU9250::displayGyro(void){
+ pc_p->printf("gx = %f", gx);
+ pc_p->printf(" gy = %f", gy);
+ pc_p->printf(" gz = %f deg/s\n\r", gz);
+}
+
+void MPU9250::displayMag(void){
+ pc_p->printf("mx = %f,", mx);
+ pc_p->printf(" my = %f,", my);
+ pc_p->printf(" mz = %f mG\n\r", mz);
+}
+
+void MPU9250::displayQuaternion(void){
+ pc_p->printf("q0 = %f\n\r", q[0]);
+ pc_p->printf("q1 = %f\n\r", q[1]);
+ pc_p->printf("q2 = %f\n\r", q[2]);
+ pc_p->printf("q3 = %f\n\r", q[3]);
+}
+
+void MPU9250::displayAngle(void){
+ //pc_p->printf("$%d %d %d;",(int)(yaw*100),(int)(pitch*100),(int)(roll*100));
+ pc_p->printf("Roll: %f\tPitch: %f\tYaw: %f\n\r", roll, pitch, yaw);
+}
+
+void MPU9250::displayTemperature(void){
+ pc_p->printf(" temperature = %f C\n\r", temperature);
+}
+
+void MPU9250::setMagBias(float bias_x, float bias_y, float bias_z){
+ magbias[0] = bias_x;
+ magbias[1] = bias_y;
+ magbias[2] = bias_z;
+}
+
+/*---------- private function ----------*/
+
+void MPU9250::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 MPU9250::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 MPU9250::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 MPU9250::initializeValue(void){
+ Ascale = AFS_2G; // AFS_2G, AFS_4G, AFS_8G, AFS_16G
+ Gscale = GFS_250DPS; // GFS_250DPS, GFS_500DPS, GFS_1000DPS, GFS_2000DPS
+ Mscale = MFS_16BITS; // MFS_14BITS or MFS_16BITS, 14-bit or 16-bit magnetometer resolution
+ Mmode = 0x06; // Either 8 Hz 0x02) or 100 Hz (0x06) magnetometer data ODR
+
+ GyroMeasError = PI * (60.0f / 180.0f);
+ beta = sqrt(3.0f / 4.0f) * GyroMeasError; // compute beta
+ GyroMeasDrift = PI * (1.0f / 180.0f); // gyroscope measurement drift in rad/s/s (start at 0.0 deg/s/s)
+ 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
+
+ deltat = 0.0f; // integration interval for both filter schemes
+ lastUpdate = 0, firstUpdate = 0, Now = 0; // used to calculate integration interval // used to calculate integration interval
+
+ for(int i=0; i<3; i++){
+ magCalibration[i] = 0;
+ gyroBias[i] = 0;
+ accelBias[i] = 0;
+ magbias[i] = 0;
+
+ eInt[i] = 0.0f;
+
+ lpmag[i] = 0.0f;
+ }
+
+ q[0] = 1.0f;
+ q[1] = 0.0f;
+ q[2] = 0.0f;
+ q[3] = 0.0f;
+}
+
+void MPU9250::initMPU9250(void)
+{
+ // Initialize MPU9250 device
+ // wake up device
+ writeByte(MPU9250_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(MPU9250_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(MPU9250_ADDRESS, CONFIG, 0x03);
+
+ // Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV)
+ writeByte(MPU9250_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(MPU9250_ADDRESS, GYRO_CONFIG); // get current GYRO_CONFIG register value
+ // c = c & ~0xE0; // Clear self-test bits [7:5]
+ c = c & ~0x02; // Clear Fchoice bits [1:0]
+ c = c & ~0x18; // Clear AFS bits [4:3]
+ c = c | Gscale << 3; // Set full scale range for the gyro
+ // c =| 0x00; // Set Fchoice for the gyro to 11 by writing its inverse to bits 1:0 of GYRO_CONFIG
+ writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c ); // Write new GYRO_CONFIG value to register
+
+ // Set accelerometer full-scale range configuration
+ c = readByte(MPU9250_ADDRESS, ACCEL_CONFIG); // get current ACCEL_CONFIG register value
+ // c = c & ~0xE0; // Clear self-test bits [7:5]
+ c = c & ~0x18; // Clear AFS bits [4:3]
+ c = c | Ascale << 3; // Set full scale range for the accelerometer
+ writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c); // Write new ACCEL_CONFIG register value
+
+ // Set accelerometer sample rate configuration
+ // It is possible to get a 4 kHz sample rate from the accelerometer by choosing 1 for
+ // accel_fchoice_b bit [3]; in this case the bandwidth is 1.13 kHz
+ c = readByte(MPU9250_ADDRESS, ACCEL_CONFIG2); // get current ACCEL_CONFIG2 register value
+ c = c & ~0x0F; // Clear accel_fchoice_b (bit 3) and A_DLPFG (bits [2:0])
+ c = c | 0x03; // Set accelerometer rate to 1 kHz and bandwidth to 41 Hz
+ writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, c); // Write new ACCEL_CONFIG2 register value
+
+ // The accelerometer, gyro, and thermometer are set to 1 kHz sample rates,
+ // but all these rates are further reduced by a factor of 5 to 200 Hz because of the SMPLRT_DIV setting
+
+ // 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(MPU9250_ADDRESS, INT_PIN_CFG, 0x22);
+ writeByte(MPU9250_ADDRESS, INT_ENABLE, 0x01); // Enable data ready (bit 0) interrupt
+}
+
+void MPU9250::initAK8963(float * destination)
+{
+ // First extract the factory calibration for each magnetometer axis
+ uint8_t rawData[3]; // x/y/z gyro calibration data stored here
+
+ writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer
+ wait(0.01);
+
+ writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x0F); // Enter Fuse ROM access mode
+ wait(0.01);
+
+ readBytes(AK8963_ADDRESS, AK8963_ASAX, 3, &rawData[0]); // Read the x-, y-, and z-axis calibration values
+ destination[0] = (float)(rawData[0] - 128)/256.0f + 1.0f; // Return x-axis sensitivity adjustment values, etc.
+ destination[1] = (float)(rawData[1] - 128)/256.0f + 1.0f;
+ destination[2] = (float)(rawData[2] - 128)/256.0f + 1.0f;
+ writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer
+ wait(0.01);
+
+ // Configure the magnetometer for continuous read and highest resolution
+ // set Mscale bit 4 to 1 (0) to enable 16 (14) bit resolution in CNTL register,
+ // and enable continuous mode data acquisition Mmode (bits [3:0]), 0010 for 8 Hz and 0110 for 100 Hz sample rates
+ writeByte(AK8963_ADDRESS, AK8963_CNTL, Mscale << 4 | Mmode); // Set magnetometer data resolution and sample ODR
+ wait(0.01);
+}
+
+void MPU9250::resetMPU9250(void)
+{
+ // reset device
+ writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
+ wait(0.1);
+}
+
+// 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 MPU9250::calibrateMPU9250(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};
+ int32_t accel_bias_reg[3] = {0, 0, 0}; // A place to hold the factory accelerometer trim biases
+
+ // reset device, reset all registers, clear gyro and accelerometer bias registers
+ writeByte(MPU9250_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(MPU9250_ADDRESS, PWR_MGMT_1, 0x01);
+ writeByte(MPU9250_ADDRESS, PWR_MGMT_2, 0x00);
+ wait(0.2);
+
+ // Configure device for bias calculation
+ writeByte(MPU9250_ADDRESS, INT_ENABLE, 0x00); // Disable all interrupts
+ writeByte(MPU9250_ADDRESS, FIFO_EN, 0x00); // Disable FIFO
+ writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x00); // Turn on internal clock source
+ writeByte(MPU9250_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master
+ writeByte(MPU9250_ADDRESS, USER_CTRL, 0x00); // Disable FIFO and I2C master modes
+ writeByte(MPU9250_ADDRESS, USER_CTRL, 0x0C); // Reset FIFO and DMP
+ wait(0.015);
+
+ // Configure MPU9250 gyro and accelerometer for bias calculation
+ writeByte(MPU9250_ADDRESS, CONFIG, 0x01); // Set low-pass filter to 188 Hz
+ writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x00); // Set sample rate to 1 kHz
+ writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 0x00); // Set gyro full-scale to 250 degrees per second, maximum sensitivity
+ writeByte(MPU9250_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(MPU9250_ADDRESS, USER_CTRL, 0x40); // Enable FIFO
+ writeByte(MPU9250_ADDRESS, FIFO_EN, 0x78); // Enable gyro and accelerometer sensors for FIFO (max size 512 bytes in MPU-9250)
+ wait(0.04); // accumulate 40 samples in 80 milliseconds = 480 bytes
+
+ // At end of sample accumulation, turn off FIFO sensor read
+ writeByte(MPU9250_ADDRESS, FIFO_EN, 0x00); // Disable gyro and accelerometer sensors for FIFO
+ readBytes(MPU9250_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(MPU9250_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(MPU9250_ADDRESS, XG_OFFSET_H, data[0]);
+ writeByte(MPU9250_ADDRESS, XG_OFFSET_L, data[1]);
+ writeByte(MPU9250_ADDRESS, YG_OFFSET_H, data[2]);
+ writeByte(MPU9250_ADDRESS, YG_OFFSET_L, data[3]);
+ writeByte(MPU9250_ADDRESS, ZG_OFFSET_H, data[4]);
+ writeByte(MPU9250_ADDRESS, ZG_OFFSET_L, 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.
+
+ readBytes(MPU9250_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(MPU9250_ADDRESS, YA_OFFSET_H, 2, &data[0]);
+ accel_bias_reg[1] = (int16_t) ((int16_t)data[0] << 8) | data[1];
+ readBytes(MPU9250_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
+
+// Apparently this is not working for the acceleration biases in the MPU-9250
+// Are we handling the temperature correction bit properly?
+// Push accelerometer biases to hardware registers
+/*
+ writeByte(MPU9250_ADDRESS, XA_OFFSET_H, data[0]);
+ writeByte(MPU9250_ADDRESS, XA_OFFSET_L, data[1]);
+ writeByte(MPU9250_ADDRESS, YA_OFFSET_H, data[2]);
+ writeByte(MPU9250_ADDRESS, YA_OFFSET_L, data[3]);
+ writeByte(MPU9250_ADDRESS, ZA_OFFSET_H, data[4]);
+ writeByte(MPU9250_ADDRESS, ZA_OFFSET_L, 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;
+}
+
+void MPU9250::getMres(void)
+{
+ switch (Mscale)
+ {
+ // Possible magnetometer scales (and their register bit settings) are:
+ // 14 bit resolution (0) and 16 bit resolution (1)
+ case MFS_14BITS:
+ mRes = 10.0*4219.0/8190.0; // Proper scale to return milliGauss
+ break;
+ case MFS_16BITS:
+ mRes = 10.0*4219.0/32760.0; // Proper scale to return milliGauss
+ break;
+ }
+}
+
+void MPU9250::getGres(void) {
+ 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 MPU9250::getAres(void)
+{
+ 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 MPU9250::readAccelData(int16_t * destination)
+{
+ uint8_t rawData[6]; // x/y/z accel register data stored here
+
+ readBytes(MPU9250_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 MPU9250::readGyroData(int16_t * destination)
+{
+ uint8_t rawData[6]; // x/y/z gyro register data stored here
+
+ readBytes(MPU9250_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 MPU9250::readMagData(int16_t * destination)
+{
+ uint8_t rawData[7]; // x/y/z gyro register data, ST2 register stored here, must read ST2 at end of data acquisition
+
+ if(readByte(AK8963_ADDRESS, AK8963_ST1) & 0x01) { // wait for magnetometer data ready bit to be set
+ readBytes(AK8963_ADDRESS, AK8963_XOUT_L, 7, &rawData[0]); // Read the six raw data and ST2 registers sequentially into data array
+ uint8_t c = rawData[6]; // End data read by reading ST2 register
+ if(!(c & 0x08)) { // Check if magnetic sensor overflow set, if not then report data
+ destination[0] = (int16_t)(((int16_t)rawData[1] << 8) | rawData[0]); // Turn the MSB and LSB into a signed 16-bit value
+ destination[1] = (int16_t)(((int16_t)rawData[3] << 8) | rawData[2]) ; // Data stored as little Endian
+ destination[2] = (int16_t)(((int16_t)rawData[5] << 8) | rawData[4]) ;
+ }
+ }
+}
+
+int16_t MPU9250::readTempData(void)
+{
+ uint8_t rawData[2]; // x/y/z gyro register data stored here
+
+ readBytes(MPU9250_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
+}
+
+uint8_t MPU9250::Whoami_MPU9250(void){
+ return readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250);
+}
+
+uint8_t MPU9250::Whoami_AK8963(void){
+ return readByte(WHO_AM_I_AK8963, WHO_AM_I_AK8963);
+}
+
+void MPU9250::sensingAccel(void){
+ readAccelData(accelCount);
+ ax = (float)accelCount[0]*aRes - accelBias[0];
+ ay = (float)accelCount[1]*aRes - accelBias[1];
+ az = (float)accelCount[2]*aRes - accelBias[2];
+}
+
+void MPU9250::sensingGyro(void){
+ readGyroData(gyroCount);
+ gx = (float)gyroCount[0]*gRes - gyroBias[0];
+ gy = (float)gyroCount[1]*gRes - gyroBias[1];
+ gz = (float)gyroCount[2]*gRes - gyroBias[2];
+}
+
+void MPU9250::sensingMag(void){
+ readMagData(magCount);
+ mx = (float)magCount[0]*mRes*magCalibration[0] - magbias[0];
+ my = (float)magCount[1]*mRes*magCalibration[1] - magbias[1];
+ mz = (float)magCount[2]*mRes*magCalibration[2] - magbias[2];
+}
+
+void MPU9250::sensingTemp(void){
+ tempCount = readTempData();
+ temperature = ((float) tempCount) / 333.87f + 21.0f; // Temperature in degrees Centigrade
+}
+
+// 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, rotation rate, and magnetic moments to produce a quaternion-based estimate of absolute
+// 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 MPU9250::MadgwickQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz, float mx, float my, float mz)
+{
+ float q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3]; // short name local variable for readability
+ float norm;
+ float hx, hy, _2bx, _2bz;
+ float s1, s2, s3, s4;
+ float qDot1, qDot2, qDot3, qDot4;
+
+ // Auxiliary variables to avoid repeated arithmetic
+ float _2q1mx;
+ float _2q1my;
+ float _2q1mz;
+ float _2q2mx;
+ float _4bx;
+ float _4bz;
+ 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;
+ float q1q1 = q1 * q1;
+ float q1q2 = q1 * q2;
+ float q1q3 = q1 * q3;
+ float q1q4 = q1 * q4;
+ float q2q2 = q2 * q2;
+ float q2q3 = q2 * q3;
+ float q2q4 = q2 * q4;
+ float q3q3 = q3 * q3;
+ float q3q4 = q3 * q4;
+ float q4q4 = q4 * 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;
+
+ // Normalise magnetometer measurement
+ norm = sqrt(mx * mx + my * my + mz * mz);
+ if (norm == 0.0f) return; // handle NaN
+ norm = 1.0f/norm;
+ mx *= norm;
+ my *= norm;
+ mz *= norm;
+
+ // Reference direction of Earth's magnetic field
+ _2q1mx = 2.0f * q1 * mx;
+ _2q1my = 2.0f * q1 * my;
+ _2q1mz = 2.0f * q1 * mz;
+ _2q2mx = 2.0f * q2 * mx;
+ hx = mx * q1q1 - _2q1my * q4 + _2q1mz * q3 + mx * q2q2 + _2q2 * my * q3 + _2q2 * mz * q4 - mx * q3q3 - mx * q4q4;
+ hy = _2q1mx * q4 + my * q1q1 - _2q1mz * q2 + _2q2mx * q3 - my * q2q2 + my * q3q3 + _2q3 * mz * q4 - my * q4q4;
+ _2bx = sqrt(hx * hx + hy * hy);
+ _2bz = -_2q1mx * q3 + _2q1my * q2 + mz * q1q1 + _2q2mx * q4 - mz * q2q2 + _2q3 * my * q4 - mz * q3q3 + mz * q4q4;
+ _4bx = 2.0f * _2bx;
+ _4bz = 2.0f * _2bz;
+
+ // Gradient decent algorithm corrective step
+ s1 = -_2q3 * (2.0f * q2q4 - _2q1q3 - ax) + _2q2 * (2.0f * q1q2 + _2q3q4 - ay) - _2bz * q3 * (_2bx * (0.5f - q3q3 - q4q4) + _2bz * (q2q4 - q1q3) - mx) + (-_2bx * q4 + _2bz * q2) * (_2bx * (q2q3 - q1q4) + _2bz * (q1q2 + q3q4) - my) + _2bx * q3 * (_2bx * (q1q3 + q2q4) + _2bz * (0.5f - q2q2 - q3q3) - mz);
+ s2 = _2q4 * (2.0f * q2q4 - _2q1q3 - ax) + _2q1 * (2.0f * q1q2 + _2q3q4 - ay) - 4.0f * q2 * (1.0f - 2.0f * q2q2 - 2.0f * q3q3 - az) + _2bz * q4 * (_2bx * (0.5f - q3q3 - q4q4) + _2bz * (q2q4 - q1q3) - mx) + (_2bx * q3 + _2bz * q1) * (_2bx * (q2q3 - q1q4) + _2bz * (q1q2 + q3q4) - my) + (_2bx * q4 - _4bz * q2) * (_2bx * (q1q3 + q2q4) + _2bz * (0.5f - q2q2 - q3q3) - mz);
+ s3 = -_2q1 * (2.0f * q2q4 - _2q1q3 - ax) + _2q4 * (2.0f * q1q2 + _2q3q4 - ay) - 4.0f * q3 * (1.0f - 2.0f * q2q2 - 2.0f * q3q3 - az) + (-_4bx * q3 - _2bz * q1) * (_2bx * (0.5f - q3q3 - q4q4) + _2bz * (q2q4 - q1q3) - mx) + (_2bx * q2 + _2bz * q4) * (_2bx * (q2q3 - q1q4) + _2bz * (q1q2 + q3q4) - my) + (_2bx * q1 - _4bz * q3) * (_2bx * (q1q3 + q2q4) + _2bz * (0.5f - q2q2 - q3q3) - mz);
+ s4 = _2q2 * (2.0f * q2q4 - _2q1q3 - ax) + _2q3 * (2.0f * q1q2 + _2q3q4 - ay) + (-_4bx * q4 + _2bz * q2) * (_2bx * (0.5f - q3q3 - q4q4) + _2bz * (q2q4 - q1q3) - mx) + (-_2bx * q1 + _2bz * q3) * (_2bx * (q2q3 - q1q4) + _2bz * (q1q2 + q3q4) - my) + _2bx * q2 * (_2bx * (q1q3 + q2q4) + _2bz * (0.5f - q2q2 - q3q3) - mz);
+ norm = sqrt(s1 * s1 + s2 * s2 + s3 * s3 + s4 * s4); // normalise step magnitude
+ norm = 1.0f/norm;
+ s1 *= norm;
+ s2 *= norm;
+ s3 *= norm;
+ s4 *= norm;
+
+ // Compute rate of change of quaternion
+ qDot1 = 0.5f * (-q2 * gx - q3 * gy - q4 * gz) - beta * s1;
+ qDot2 = 0.5f * (q1 * gx + q3 * gz - q4 * gy) - beta * s2;
+ qDot3 = 0.5f * (q1 * gy - q2 * gz + q4 * gx) - beta * s3;
+ qDot4 = 0.5f * (q1 * gz + q2 * gy - q3 * gx) - beta * s4;
+
+ // Integrate to yield quaternion
+ q1 += qDot1 * deltat;
+ q2 += qDot2 * deltat;
+ q3 += qDot3 * deltat;
+ q4 += qDot4 * deltat;
+ 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;
+
+}
+
+void MPU9250::MahonyQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz, float mx, float my, float mz)
+{
+ float q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3]; // short name local variable for readability
+ float norm;
+ float hx, hy, bx, bz;
+ float vx, vy, vz, wx, wy, wz;
+ float ex, ey, ez;
+ float pa, pb, pc;
+
+ // Auxiliary variables to avoid repeated arithmetic
+ float q1q1 = q1 * q1;
+ float q1q2 = q1 * q2;
+ float q1q3 = q1 * q3;
+ float q1q4 = q1 * q4;
+ float q2q2 = q2 * q2;
+ float q2q3 = q2 * q3;
+ float q2q4 = q2 * q4;
+ float q3q3 = q3 * q3;
+ float q3q4 = q3 * q4;
+ float q4q4 = q4 * q4;
+
+ // Normalise accelerometer measurement
+ norm = sqrt(ax * ax + ay * ay + az * az);
+ if (norm == 0.0f) return; // handle NaN
+ norm = 1.0f / norm; // use reciprocal for division
+ ax *= norm;
+ ay *= norm;
+ az *= norm;
+
+ // Normalise magnetometer measurement
+ norm = sqrt(mx * mx + my * my + mz * mz);
+ if (norm == 0.0f) return; // handle NaN
+ norm = 1.0f / norm; // use reciprocal for division
+ mx *= norm;
+ my *= norm;
+ mz *= norm;
+
+ // Reference direction of Earth's magnetic field
+ hx = 2.0f * mx * (0.5f - q3q3 - q4q4) + 2.0f * my * (q2q3 - q1q4) + 2.0f * mz * (q2q4 + q1q3);
+ hy = 2.0f * mx * (q2q3 + q1q4) + 2.0f * my * (0.5f - q2q2 - q4q4) + 2.0f * mz * (q3q4 - q1q2);
+ bx = sqrt((hx * hx) + (hy * hy));
+ bz = 2.0f * mx * (q2q4 - q1q3) + 2.0f * my * (q3q4 + q1q2) + 2.0f * mz * (0.5f - q2q2 - q3q3);
+
+ // Estimated direction of gravity and magnetic field
+ vx = 2.0f * (q2q4 - q1q3);
+ vy = 2.0f * (q1q2 + q3q4);
+ vz = q1q1 - q2q2 - q3q3 + q4q4;
+ wx = 2.0f * bx * (0.5f - q3q3 - q4q4) + 2.0f * bz * (q2q4 - q1q3);
+ wy = 2.0f * bx * (q2q3 - q1q4) + 2.0f * bz * (q1q2 + q3q4);
+ wz = 2.0f * bx * (q1q3 + q2q4) + 2.0f * bz * (0.5f - q2q2 - q3q3);
+
+ // Error is cross product between estimated direction and measured direction of gravity
+ ex = (ay * vz - az * vy) + (my * wz - mz * wy);
+ ey = (az * vx - ax * vz) + (mz * wx - mx * wz);
+ ez = (ax * vy - ay * vx) + (mx * wy - my * wx);
+ if (Ki > 0.0f){
+ eInt[0] += ex; // accumulate integral error
+ eInt[1] += ey;
+ eInt[2] += ez;
+
+ }else{
+ eInt[0] = 0.0f; // prevent integral wind up
+ eInt[1] = 0.0f;
+ eInt[2] = 0.0f;
+ }
+
+ // Apply feedback terms
+ gx = gx + Kp * ex + Ki * eInt[0];
+ gy = gy + Kp * ey + Ki * eInt[1];
+ gz = gz + Kp * ez + Ki * eInt[2];
+
+ // Integrate rate of change of quaternion
+ pa = q2;
+ pb = q3;
+ pc = q4;
+ q1 = q1 + (-q2 * gx - q3 * gy - q4 * gz) * (0.5f * deltat);
+ q2 = pa + (q1 * gx + pb * gz - pc * gy) * (0.5f * deltat);
+ q3 = pb + (q1 * gy - pa * gz + pc * gx) * (0.5f * deltat);
+ q4 = pc + (q1 * gz + pa * gy - pb * gx) * (0.5f * deltat);
+
+ // Normalise quaternion
+ norm = sqrt(q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4);
+ norm = 1.0f / norm;
+ q[0] = q1 * norm;
+ q[1] = q2 * norm;
+ q[2] = q3 * norm;
+ q[3] = q4 * norm;
+
+}
+
+void MPU9250::translateQuaternionToDeg(float quaternion[4]){
+ yaw = atan2(2.0f * (quaternion[1] * quaternion[2] + quaternion[0] * quaternion[3]), quaternion[0] * quaternion[0] + quaternion[1] * quaternion[1] - quaternion[2] * quaternion[2] - quaternion[3] * quaternion[3]);
+ roll = -asin(2.0f * (quaternion[1] * quaternion[3] - quaternion[0] * quaternion[2]));
+ pitch = atan2(2.0f * (quaternion[0] * quaternion[1] + quaternion[2] * quaternion[3]), quaternion[0] * quaternion[0] - quaternion[1] * quaternion[1] - quaternion[2] * quaternion[2] + quaternion[3] * quaternion[3]);
+}
+
+void MPU9250::calibrateDegree(void){
+ pitch *= 180.0f / PI;
+ yaw *= 180.0f / PI;
+ yaw -= DECLINATION;
+ roll *= 180.0f / PI;
+}
+
+void MPU9250::transformCoordinateFromCompassToMPU(){
+ float buf = mx;
+ mx = my;
+ my = buf;
+ mz = -mz;
+}
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