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MPU9250.h
00001 #ifndef MPU9250_H 00002 #define MPU9250_H 00003 00004 #include "mbed.h" 00005 #include "math.h" 00006 00007 // See also MPU-9250 Register Map and Descriptions, Revision 4.0, RM-MPU-9250A-00, Rev. 1.4, 9/9/2013 for registers not listed in 00008 // above document; the MPU9250 and MPU9150 are virtually identical but the latter has a different register map 00009 // 00010 //Magnetometer Registers 00011 #define AK8963_ADDRESS 0x0C<<1 00012 #define WHO_AM_I_AK8963 0x00 // should return 0x48 00013 #define INFO 0x01 00014 #define AK8963_ST1 0x02 // data ready status bit 0 00015 #define AK8963_XOUT_L 0x03 // data 00016 #define AK8963_XOUT_H 0x04 00017 #define AK8963_YOUT_L 0x05 00018 #define AK8963_YOUT_H 0x06 00019 #define AK8963_ZOUT_L 0x07 00020 #define AK8963_ZOUT_H 0x08 00021 #define AK8963_ST2 0x09 // Data overflow bit 3 and data read error status bit 2 00022 #define AK8963_CNTL 0x0A // Power down (0000), single-measurement (0001), self-test (1000) and Fuse ROM (1111) modes on bits 3:0 00023 #define AK8963_ASTC 0x0C // Self test control 00024 #define AK8963_I2CDIS 0x0F // I2C disable 00025 #define AK8963_ASAX 0x10 // Fuse ROM x-axis sensitivity adjustment value 00026 #define AK8963_ASAY 0x11 // Fuse ROM y-axis sensitivity adjustment value 00027 #define AK8963_ASAZ 0x12 // Fuse ROM z-axis sensitivity adjustment value 00028 00029 #define SELF_TEST_X_GYRO 0x00 00030 #define SELF_TEST_Y_GYRO 0x01 00031 #define SELF_TEST_Z_GYRO 0x02 00032 00033 /*#define X_FINE_GAIN 0x03 // [7:0] fine gain 00034 #define Y_FINE_GAIN 0x04 00035 #define Z_FINE_GAIN 0x05 00036 #define XA_OFFSET_H 0x06 // User-defined trim values for accelerometer 00037 #define XA_OFFSET_L_TC 0x07 00038 #define YA_OFFSET_H 0x08 00039 #define YA_OFFSET_L_TC 0x09 00040 #define ZA_OFFSET_H 0x0A 00041 #define ZA_OFFSET_L_TC 0x0B */ 00042 00043 #define SELF_TEST_X_ACCEL 0x0D 00044 #define SELF_TEST_Y_ACCEL 0x0E 00045 #define SELF_TEST_Z_ACCEL 0x0F 00046 00047 #define SELF_TEST_A 0x10 00048 00049 #define XG_OFFSET_H 0x13 // User-defined trim values for gyroscope 00050 #define XG_OFFSET_L 0x14 00051 #define YG_OFFSET_H 0x15 00052 #define YG_OFFSET_L 0x16 00053 #define ZG_OFFSET_H 0x17 00054 #define ZG_OFFSET_L 0x18 00055 #define SMPLRT_DIV 0x19 00056 #define CONFIG 0x1A 00057 #define GYRO_CONFIG 0x1B 00058 #define ACCEL_CONFIG 0x1C 00059 #define ACCEL_CONFIG2 0x1D 00060 #define LP_ACCEL_ODR 0x1E 00061 #define WOM_THR 0x1F 00062 00063 #define MOT_DUR 0x20 // Duration counter threshold for motion interrupt generation, 1 kHz rate, LSB = 1 ms 00064 #define ZMOT_THR 0x21 // Zero-motion detection threshold bits [7:0] 00065 #define ZRMOT_DUR 0x22 // Duration counter threshold for zero motion interrupt generation, 16 Hz rate, LSB = 64 ms 00066 00067 #define FIFO_EN 0x23 00068 #define I2C_MST_CTRL 0x24 00069 #define I2C_SLV0_ADDR 0x25 00070 #define I2C_SLV0_REG 0x26 00071 #define I2C_SLV0_CTRL 0x27 00072 #define I2C_SLV1_ADDR 0x28 00073 #define I2C_SLV1_REG 0x29 00074 #define I2C_SLV1_CTRL 0x2A 00075 #define I2C_SLV2_ADDR 0x2B 00076 #define I2C_SLV2_REG 0x2C 00077 #define I2C_SLV2_CTRL 0x2D 00078 #define I2C_SLV3_ADDR 0x2E 00079 #define I2C_SLV3_REG 0x2F 00080 #define I2C_SLV3_CTRL 0x30 00081 #define I2C_SLV4_ADDR 0x31 00082 #define I2C_SLV4_REG 0x32 00083 #define I2C_SLV4_DO 0x33 00084 #define I2C_SLV4_CTRL 0x34 00085 #define I2C_SLV4_DI 0x35 00086 #define I2C_MST_STATUS 0x36 00087 #define INT_PIN_CFG 0x37 00088 #define INT_ENABLE 0x38 00089 #define DMP_INT_STATUS 0x39 // Check DMP interrupt 00090 #define INT_STATUS 0x3A 00091 #define ACCEL_XOUT_H 0x3B 00092 #define ACCEL_XOUT_L 0x3C 00093 #define ACCEL_YOUT_H 0x3D 00094 #define ACCEL_YOUT_L 0x3E 00095 #define ACCEL_ZOUT_H 0x3F 00096 #define ACCEL_ZOUT_L 0x40 00097 #define TEMP_OUT_H 0x41 00098 #define TEMP_OUT_L 0x42 00099 #define GYRO_XOUT_H 0x43 00100 #define GYRO_XOUT_L 0x44 00101 #define GYRO_YOUT_H 0x45 00102 #define GYRO_YOUT_L 0x46 00103 #define GYRO_ZOUT_H 0x47 00104 #define GYRO_ZOUT_L 0x48 00105 #define EXT_SENS_DATA_00 0x49 00106 #define EXT_SENS_DATA_01 0x4A 00107 #define EXT_SENS_DATA_02 0x4B 00108 #define EXT_SENS_DATA_03 0x4C 00109 #define EXT_SENS_DATA_04 0x4D 00110 #define EXT_SENS_DATA_05 0x4E 00111 #define EXT_SENS_DATA_06 0x4F 00112 #define EXT_SENS_DATA_07 0x50 00113 #define EXT_SENS_DATA_08 0x51 00114 #define EXT_SENS_DATA_09 0x52 00115 #define EXT_SENS_DATA_10 0x53 00116 #define EXT_SENS_DATA_11 0x54 00117 #define EXT_SENS_DATA_12 0x55 00118 #define EXT_SENS_DATA_13 0x56 00119 #define EXT_SENS_DATA_14 0x57 00120 #define EXT_SENS_DATA_15 0x58 00121 #define EXT_SENS_DATA_16 0x59 00122 #define EXT_SENS_DATA_17 0x5A 00123 #define EXT_SENS_DATA_18 0x5B 00124 #define EXT_SENS_DATA_19 0x5C 00125 #define EXT_SENS_DATA_20 0x5D 00126 #define EXT_SENS_DATA_21 0x5E 00127 #define EXT_SENS_DATA_22 0x5F 00128 #define EXT_SENS_DATA_23 0x60 00129 #define MOT_DETECT_STATUS 0x61 00130 #define I2C_SLV0_DO 0x63 00131 #define I2C_SLV1_DO 0x64 00132 #define I2C_SLV2_DO 0x65 00133 #define I2C_SLV3_DO 0x66 00134 #define I2C_MST_DELAY_CTRL 0x67 00135 #define SIGNAL_PATH_RESET 0x68 00136 #define MOT_DETECT_CTRL 0x69 00137 #define USER_CTRL 0x6A // Bit 7 enable DMP, bit 3 reset DMP 00138 #define PWR_MGMT_1 0x6B // Device defaults to the SLEEP mode 00139 #define PWR_MGMT_2 0x6C 00140 #define DMP_BANK 0x6D // Activates a specific bank in the DMP 00141 #define DMP_RW_PNT 0x6E // Set read/write pointer to a specific start address in specified DMP bank 00142 #define DMP_REG 0x6F // Register in DMP from which to read or to which to write 00143 #define DMP_REG_1 0x70 00144 #define DMP_REG_2 0x71 00145 #define FIFO_COUNTH 0x72 00146 #define FIFO_COUNTL 0x73 00147 #define FIFO_R_W 0x74 00148 #define WHO_AM_I_MPU9250 0x75 // Should return 0x71 00149 #define XA_OFFSET_H 0x77 00150 #define XA_OFFSET_L 0x78 00151 #define YA_OFFSET_H 0x7A 00152 #define YA_OFFSET_L 0x7B 00153 #define ZA_OFFSET_H 0x7D 00154 #define ZA_OFFSET_L 0x7E 00155 00156 // Using the MSENSR-9250 breakout board, ADO is set to 0 00157 // Seven-bit device address is 110100 for ADO = 0 and 110101 for ADO = 1 00158 //mbed uses the eight-bit device address, so shift seven-bit addresses left by one! 00159 #define ADO 0 00160 #if ADO 00161 #define MPU9250_ADDRESS 0x69<<1 // Device address when ADO = 1 00162 #else 00163 #define MPU9250_ADDRESS 0x68<<1 // Device address when ADO = 0 00164 #endif 00165 00166 // Set initial input parameters 00167 enum Ascale { 00168 AFS_2G = 0, 00169 AFS_4G, 00170 AFS_8G, 00171 AFS_16G 00172 }; 00173 00174 enum Gscale { 00175 GFS_250DPS = 0, 00176 GFS_500DPS, 00177 GFS_1000DPS, 00178 GFS_2000DPS 00179 }; 00180 00181 enum Mscale { 00182 MFS_14BITS = 0, // 0.6 mG per LSB 00183 MFS_16BITS // 0.15 mG per LSB 00184 }; 00185 00186 uint8_t Ascale = AFS_2G; // AFS_2G, AFS_4G, AFS_8G, AFS_16G 00187 uint8_t Gscale = GFS_250DPS; // GFS_250DPS, GFS_500DPS, GFS_1000DPS, GFS_2000DPS 00188 uint8_t Mscale = MFS_16BITS; // MFS_14BITS or MFS_16BITS, 14-bit or 16-bit magnetometer resolution 00189 uint8_t Mmode = 0x06; // Either 8 Hz 0x02) or 100 Hz (0x06) magnetometer data ODR 00190 float aRes, gRes, mRes; // scale resolutions per LSB for the sensors 00191 00192 //Set up I2C, (SDA,SCL) 00193 I2C i2c(p28, p27); 00194 00195 DigitalOut myled(LED1); 00196 00197 // Pin definitions 00198 int intPin = 12; // These can be changed, 2 and 3 are the Arduinos ext int pins 00199 00200 int16_t accelCount[3]; // Stores the 16-bit signed accelerometer sensor output 00201 int16_t gyroCount[3]; // Stores the 16-bit signed gyro sensor output 00202 int16_t magCount[3]; // Stores the 16-bit signed magnetometer sensor output 00203 float magCalibration[3] = {0, 0, 0}, magbias[3] = {0, 0, 0}; // Factory mag calibration and mag bias 00204 float gyroBias[3] = {0, 0, 0}, accelBias[3] = {0, 0, 0}; // Bias corrections for gyro and accelerometer 00205 float ax, ay, az, gx, gy, gz, mx, my, mz; // variables to hold latest sensor data values 00206 int16_t tempCount; // Stores the real internal chip temperature in degrees Celsius 00207 float temperature; 00208 float SelfTest[6]; 00209 00210 int delt_t = 0; // used to control display output rate 00211 int count = 0; // used to control display output rate 00212 00213 // parameters for 6 DoF sensor fusion calculations 00214 float PI = 3.14159265358979323846f; 00215 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 00216 float beta = sqrt(3.0f / 4.0f) * GyroMeasError; // compute beta 00217 float GyroMeasDrift = PI * (1.0f / 180.0f); // gyroscope measurement drift in rad/s/s (start at 0.0 deg/s/s) 00218 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 00219 #define Kp 2.0f * 5.0f // these are the free parameters in the Mahony filter and fusion scheme, Kp for proportional feedback, Ki for integral 00220 #define Ki 0.0f 00221 00222 float pitch, yaw, roll; 00223 float deltat = 0.0f; // integration interval for both filter schemes 00224 int lastUpdate = 0, firstUpdate = 0, Now = 0; // used to calculate integration interval // used to calculate integration interval 00225 float q[4] = {1.0f, 0.0f, 0.0f, 0.0f}; // vector to hold quaternion 00226 float eInt[3] = {0.0f, 0.0f, 0.0f}; // vector to hold integral error for Mahony method 00227 00228 class MPU9250 { 00229 00230 protected: 00231 00232 public: 00233 //=================================================================================================================== 00234 //====== Set of useful function to access acceleratio, gyroscope, and temperature data 00235 //=================================================================================================================== 00236 00237 void writeByte(uint8_t address, uint8_t subAddress, uint8_t data) 00238 { 00239 char data_write[2]; 00240 data_write[0] = subAddress; 00241 data_write[1] = data; 00242 i2c.write(address, data_write, 2, 0); 00243 } 00244 00245 char readByte(uint8_t address, uint8_t subAddress) 00246 { 00247 char data[1]; // `data` will store the register data 00248 char data_write[1]; 00249 data_write[0] = subAddress; 00250 i2c.write(address, data_write, 1, 1); // no stop 00251 i2c.read(address, data, 1, 0); 00252 return data[0]; 00253 } 00254 00255 void readBytes(uint8_t address, uint8_t subAddress, uint8_t count, uint8_t * dest) 00256 { 00257 char data[14]; 00258 char data_write[1]; 00259 data_write[0] = subAddress; 00260 i2c.write(address, data_write, 1, 1); // no stop 00261 i2c.read(address, data, count, 0); 00262 for(int ii = 0; ii < count; ii++) { 00263 dest[ii] = data[ii]; 00264 } 00265 } 00266 00267 00268 void getMres() { 00269 switch (Mscale) 00270 { 00271 // Possible magnetometer scales (and their register bit settings) are: 00272 // 14 bit resolution (0) and 16 bit resolution (1) 00273 case MFS_14BITS: 00274 mRes = 10.0*4219.0/8190.0; // Proper scale to return milliGauss 00275 break; 00276 case MFS_16BITS: 00277 mRes = 10.0*4219.0/32760.0; // Proper scale to return milliGauss 00278 break; 00279 } 00280 } 00281 00282 00283 void getGres() { 00284 switch (Gscale) 00285 { 00286 // Possible gyro scales (and their register bit settings) are: 00287 // 250 DPS (00), 500 DPS (01), 1000 DPS (10), and 2000 DPS (11). 00288 // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value: 00289 case GFS_250DPS: 00290 gRes = 250.0/32768.0; 00291 break; 00292 case GFS_500DPS: 00293 gRes = 500.0/32768.0; 00294 break; 00295 case GFS_1000DPS: 00296 gRes = 1000.0/32768.0; 00297 break; 00298 case GFS_2000DPS: 00299 gRes = 2000.0/32768.0; 00300 break; 00301 } 00302 } 00303 00304 00305 void getAres() { 00306 switch (Ascale) 00307 { 00308 // Possible accelerometer scales (and their register bit settings) are: 00309 // 2 Gs (00), 4 Gs (01), 8 Gs (10), and 16 Gs (11). 00310 // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value: 00311 case AFS_2G: 00312 aRes = 2.0/32768.0; 00313 break; 00314 case AFS_4G: 00315 aRes = 4.0/32768.0; 00316 break; 00317 case AFS_8G: 00318 aRes = 8.0/32768.0; 00319 break; 00320 case AFS_16G: 00321 aRes = 16.0/32768.0; 00322 break; 00323 } 00324 } 00325 00326 00327 void readAccelData(int16_t * destination) 00328 { 00329 uint8_t rawData[6]; // x/y/z accel register data stored here 00330 readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array 00331 destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00332 destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00333 destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00334 } 00335 00336 void readGyroData(int16_t * destination) 00337 { 00338 uint8_t rawData[6]; // x/y/z gyro register data stored here 00339 readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array 00340 destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00341 destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00342 destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00343 } 00344 00345 void readMagData(int16_t * destination) 00346 { 00347 uint8_t rawData[7]; // x/y/z gyro register data, ST2 register stored here, must read ST2 at end of data acquisition 00348 if(readByte(AK8963_ADDRESS, AK8963_ST1) & 0x01) { // wait for magnetometer data ready bit to be set 00349 readBytes(AK8963_ADDRESS, AK8963_XOUT_L, 7, &rawData[0]); // Read the six raw data and ST2 registers sequentially into data array 00350 uint8_t c = rawData[6]; // End data read by reading ST2 register 00351 if(!(c & 0x08)) { // Check if magnetic sensor overflow set, if not then report data 00352 destination[0] = (int16_t)(((int16_t)rawData[1] << 8) | rawData[0]); // Turn the MSB and LSB into a signed 16-bit value 00353 destination[1] = (int16_t)(((int16_t)rawData[3] << 8) | rawData[2]) ; // Data stored as little Endian 00354 destination[2] = (int16_t)(((int16_t)rawData[5] << 8) | rawData[4]) ; 00355 } 00356 } 00357 } 00358 00359 int16_t readTempData() 00360 { 00361 uint8_t rawData[2]; // x/y/z gyro register data stored here 00362 readBytes(MPU9250_ADDRESS, TEMP_OUT_H, 2, &rawData[0]); // Read the two raw data registers sequentially into data array 00363 return (int16_t)(((int16_t)rawData[0]) << 8 | rawData[1]) ; // Turn the MSB and LSB into a 16-bit value 00364 } 00365 00366 00367 void resetMPU9250() { 00368 // reset device 00369 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device 00370 wait(0.1); 00371 } 00372 00373 void initAK8963(float * destination) 00374 { 00375 // First extract the factory calibration for each magnetometer axis 00376 uint8_t rawData[3]; // x/y/z gyro calibration data stored here 00377 writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer 00378 wait(0.01); 00379 writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x0F); // Enter Fuse ROM access mode 00380 wait(0.01); 00381 readBytes(AK8963_ADDRESS, AK8963_ASAX, 3, &rawData[0]); // Read the x-, y-, and z-axis calibration values 00382 destination[0] = (float)(rawData[0] - 128)/256.0f + 1.0f; // Return x-axis sensitivity adjustment values, etc. 00383 destination[1] = (float)(rawData[1] - 128)/256.0f + 1.0f; 00384 destination[2] = (float)(rawData[2] - 128)/256.0f + 1.0f; 00385 writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer 00386 wait(0.01); 00387 // Configure the magnetometer for continuous read and highest resolution 00388 // set Mscale bit 4 to 1 (0) to enable 16 (14) bit resolution in CNTL register, 00389 // and enable continuous mode data acquisition Mmode (bits [3:0]), 0010 for 8 Hz and 0110 for 100 Hz sample rates 00390 writeByte(AK8963_ADDRESS, AK8963_CNTL, Mscale << 4 | Mmode); // Set magnetometer data resolution and sample ODR 00391 wait(0.01); 00392 } 00393 00394 00395 void initMPU9250() 00396 { 00397 // Initialize MPU9250 device 00398 // wake up device 00399 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x00); // Clear sleep mode bit (6), enable all sensors 00400 wait(0.1); // Delay 100 ms for PLL to get established on x-axis gyro; should check for PLL ready interrupt 00401 00402 // get stable time source 00403 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x01); // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001 00404 00405 // Configure Gyro and Accelerometer 00406 // Disable FSYNC and set accelerometer and gyro bandwidth to 44 and 42 Hz, respectively; 00407 // DLPF_CFG = bits 2:0 = 010; this sets the sample rate at 1 kHz for both 00408 // Maximum delay is 4.9 ms which is just over a 200 Hz maximum rate 00409 writeByte(MPU9250_ADDRESS, CONFIG, 0x03); 00410 00411 // Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV) 00412 writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x04); // Use a 200 Hz rate; the same rate set in CONFIG above 00413 00414 // Set gyroscope full scale range 00415 // Range selects FS_SEL and AFS_SEL are 0 - 3, so 2-bit values are left-shifted into positions 4:3 00416 uint8_t c = readByte(MPU9250_ADDRESS, GYRO_CONFIG); 00417 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] 00418 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c & ~0x18); // Clear AFS bits [4:3] 00419 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c | Gscale << 3); // Set full scale range for the gyro 00420 00421 // Set accelerometer configuration 00422 c = readByte(MPU9250_ADDRESS, ACCEL_CONFIG); 00423 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] 00424 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c & ~0x18); // Clear AFS bits [4:3] 00425 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c | Ascale << 3); // Set full scale range for the accelerometer 00426 00427 // Set accelerometer sample rate configuration 00428 // It is possible to get a 4 kHz sample rate from the accelerometer by choosing 1 for 00429 // accel_fchoice_b bit [3]; in this case the bandwidth is 1.13 kHz 00430 c = readByte(MPU9250_ADDRESS, ACCEL_CONFIG2); 00431 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, c & ~0x0F); // Clear accel_fchoice_b (bit 3) and A_DLPFG (bits [2:0]) 00432 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, c | 0x03); // Set accelerometer rate to 1 kHz and bandwidth to 41 Hz 00433 00434 // The accelerometer, gyro, and thermometer are set to 1 kHz sample rates, 00435 // but all these rates are further reduced by a factor of 5 to 200 Hz because of the SMPLRT_DIV setting 00436 00437 // Configure Interrupts and Bypass Enable 00438 // Set interrupt pin active high, push-pull, and clear on read of INT_STATUS, enable I2C_BYPASS_EN so additional chips 00439 // can join the I2C bus and all can be controlled by the Arduino as master 00440 writeByte(MPU9250_ADDRESS, INT_PIN_CFG, 0x22); 00441 writeByte(MPU9250_ADDRESS, INT_ENABLE, 0x01); // Enable data ready (bit 0) interrupt 00442 } 00443 00444 // Function which accumulates gyro and accelerometer data after device initialization. It calculates the average 00445 // of the at-rest readings and then loads the resulting offsets into accelerometer and gyro bias registers. 00446 void calibrateMPU9250(float * dest1, float * dest2) 00447 { 00448 uint8_t data[12]; // data array to hold accelerometer and gyro x, y, z, data 00449 uint16_t ii, packet_count, fifo_count; 00450 int32_t gyro_bias[3] = {0, 0, 0}, accel_bias[3] = {0, 0, 0}; 00451 00452 // reset device, reset all registers, clear gyro and accelerometer bias registers 00453 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device 00454 wait(0.1); 00455 00456 // get stable time source 00457 // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001 00458 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x01); 00459 writeByte(MPU9250_ADDRESS, PWR_MGMT_2, 0x00); 00460 wait(0.2); 00461 00462 // Configure device for bias calculation 00463 writeByte(MPU9250_ADDRESS, INT_ENABLE, 0x00); // Disable all interrupts 00464 writeByte(MPU9250_ADDRESS, FIFO_EN, 0x00); // Disable FIFO 00465 writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x00); // Turn on internal clock source 00466 writeByte(MPU9250_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master 00467 writeByte(MPU9250_ADDRESS, USER_CTRL, 0x00); // Disable FIFO and I2C master modes 00468 writeByte(MPU9250_ADDRESS, USER_CTRL, 0x0C); // Reset FIFO and DMP 00469 wait(0.015); 00470 00471 // Configure MPU9250 gyro and accelerometer for bias calculation 00472 writeByte(MPU9250_ADDRESS, CONFIG, 0x01); // Set low-pass filter to 188 Hz 00473 writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x00); // Set sample rate to 1 kHz 00474 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 0x00); // Set gyro full-scale to 250 degrees per second, maximum sensitivity 00475 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity 00476 00477 uint16_t gyrosensitivity = 131; // = 131 LSB/degrees/sec 00478 uint16_t accelsensitivity = 16384; // = 16384 LSB/g 00479 00480 // Configure FIFO to capture accelerometer and gyro data for bias calculation 00481 writeByte(MPU9250_ADDRESS, USER_CTRL, 0x40); // Enable FIFO 00482 writeByte(MPU9250_ADDRESS, FIFO_EN, 0x78); // Enable gyro and accelerometer sensors for FIFO (max size 512 bytes in MPU-9250) 00483 wait(0.04); // accumulate 40 samples in 80 milliseconds = 480 bytes 00484 00485 // At end of sample accumulation, turn off FIFO sensor read 00486 writeByte(MPU9250_ADDRESS, FIFO_EN, 0x00); // Disable gyro and accelerometer sensors for FIFO 00487 readBytes(MPU9250_ADDRESS, FIFO_COUNTH, 2, &data[0]); // read FIFO sample count 00488 fifo_count = ((uint16_t)data[0] << 8) | data[1]; 00489 packet_count = fifo_count/12;// How many sets of full gyro and accelerometer data for averaging 00490 00491 for (ii = 0; ii < packet_count; ii++) { 00492 int16_t accel_temp[3] = {0, 0, 0}, gyro_temp[3] = {0, 0, 0}; 00493 readBytes(MPU9250_ADDRESS, FIFO_R_W, 12, &data[0]); // read data for averaging 00494 accel_temp[0] = (int16_t) (((int16_t)data[0] << 8) | data[1] ) ; // Form signed 16-bit integer for each sample in FIFO 00495 accel_temp[1] = (int16_t) (((int16_t)data[2] << 8) | data[3] ) ; 00496 accel_temp[2] = (int16_t) (((int16_t)data[4] << 8) | data[5] ) ; 00497 gyro_temp[0] = (int16_t) (((int16_t)data[6] << 8) | data[7] ) ; 00498 gyro_temp[1] = (int16_t) (((int16_t)data[8] << 8) | data[9] ) ; 00499 gyro_temp[2] = (int16_t) (((int16_t)data[10] << 8) | data[11]) ; 00500 00501 accel_bias[0] += (int32_t) accel_temp[0]; // Sum individual signed 16-bit biases to get accumulated signed 32-bit biases 00502 accel_bias[1] += (int32_t) accel_temp[1]; 00503 accel_bias[2] += (int32_t) accel_temp[2]; 00504 gyro_bias[0] += (int32_t) gyro_temp[0]; 00505 gyro_bias[1] += (int32_t) gyro_temp[1]; 00506 gyro_bias[2] += (int32_t) gyro_temp[2]; 00507 00508 } 00509 accel_bias[0] /= (int32_t) packet_count; // Normalize sums to get average count biases 00510 accel_bias[1] /= (int32_t) packet_count; 00511 accel_bias[2] /= (int32_t) packet_count; 00512 gyro_bias[0] /= (int32_t) packet_count; 00513 gyro_bias[1] /= (int32_t) packet_count; 00514 gyro_bias[2] /= (int32_t) packet_count; 00515 00516 if(accel_bias[2] > 0L) {accel_bias[2] -= (int32_t) accelsensitivity;} // Remove gravity from the z-axis accelerometer bias calculation 00517 else {accel_bias[2] += (int32_t) accelsensitivity;} 00518 00519 // Construct the gyro biases for push to the hardware gyro bias registers, which are reset to zero upon device startup 00520 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 00521 data[1] = (-gyro_bias[0]/4) & 0xFF; // Biases are additive, so change sign on calculated average gyro biases 00522 data[2] = (-gyro_bias[1]/4 >> 8) & 0xFF; 00523 data[3] = (-gyro_bias[1]/4) & 0xFF; 00524 data[4] = (-gyro_bias[2]/4 >> 8) & 0xFF; 00525 data[5] = (-gyro_bias[2]/4) & 0xFF; 00526 00527 /// Push gyro biases to hardware registers 00528 /* writeByte(MPU9250_ADDRESS, XG_OFFSET_H, data[0]); 00529 writeByte(MPU9250_ADDRESS, XG_OFFSET_L, data[1]); 00530 writeByte(MPU9250_ADDRESS, YG_OFFSET_H, data[2]); 00531 writeByte(MPU9250_ADDRESS, YG_OFFSET_L, data[3]); 00532 writeByte(MPU9250_ADDRESS, ZG_OFFSET_H, data[4]); 00533 writeByte(MPU9250_ADDRESS, ZG_OFFSET_L, data[5]); 00534 */ 00535 dest1[0] = (float) gyro_bias[0]/(float) gyrosensitivity; // construct gyro bias in deg/s for later manual subtraction 00536 dest1[1] = (float) gyro_bias[1]/(float) gyrosensitivity; 00537 dest1[2] = (float) gyro_bias[2]/(float) gyrosensitivity; 00538 00539 // Construct the accelerometer biases for push to the hardware accelerometer bias registers. These registers contain 00540 // factory trim values which must be added to the calculated accelerometer biases; on boot up these registers will hold 00541 // non-zero values. In addition, bit 0 of the lower byte must be preserved since it is used for temperature 00542 // compensation calculations. Accelerometer bias registers expect bias input as 2048 LSB per g, so that 00543 // the accelerometer biases calculated above must be divided by 8. 00544 00545 int32_t accel_bias_reg[3] = {0, 0, 0}; // A place to hold the factory accelerometer trim biases 00546 readBytes(MPU9250_ADDRESS, XA_OFFSET_H, 2, &data[0]); // Read factory accelerometer trim values 00547 accel_bias_reg[0] = (int16_t) ((int16_t)data[0] << 8) | data[1]; 00548 readBytes(MPU9250_ADDRESS, YA_OFFSET_H, 2, &data[0]); 00549 accel_bias_reg[1] = (int16_t) ((int16_t)data[0] << 8) | data[1]; 00550 readBytes(MPU9250_ADDRESS, ZA_OFFSET_H, 2, &data[0]); 00551 accel_bias_reg[2] = (int16_t) ((int16_t)data[0] << 8) | data[1]; 00552 00553 uint32_t mask = 1uL; // Define mask for temperature compensation bit 0 of lower byte of accelerometer bias registers 00554 uint8_t mask_bit[3] = {0, 0, 0}; // Define array to hold mask bit for each accelerometer bias axis 00555 00556 for(ii = 0; ii < 3; ii++) { 00557 if(accel_bias_reg[ii] & mask) mask_bit[ii] = 0x01; // If temperature compensation bit is set, record that fact in mask_bit 00558 } 00559 00560 // Construct total accelerometer bias, including calculated average accelerometer bias from above 00561 accel_bias_reg[0] -= (accel_bias[0]/8); // Subtract calculated averaged accelerometer bias scaled to 2048 LSB/g (16 g full scale) 00562 accel_bias_reg[1] -= (accel_bias[1]/8); 00563 accel_bias_reg[2] -= (accel_bias[2]/8); 00564 00565 data[0] = (accel_bias_reg[0] >> 8) & 0xFF; 00566 data[1] = (accel_bias_reg[0]) & 0xFF; 00567 data[1] = data[1] | mask_bit[0]; // preserve temperature compensation bit when writing back to accelerometer bias registers 00568 data[2] = (accel_bias_reg[1] >> 8) & 0xFF; 00569 data[3] = (accel_bias_reg[1]) & 0xFF; 00570 data[3] = data[3] | mask_bit[1]; // preserve temperature compensation bit when writing back to accelerometer bias registers 00571 data[4] = (accel_bias_reg[2] >> 8) & 0xFF; 00572 data[5] = (accel_bias_reg[2]) & 0xFF; 00573 data[5] = data[5] | mask_bit[2]; // preserve temperature compensation bit when writing back to accelerometer bias registers 00574 00575 // Apparently this is not working for the acceleration biases in the MPU-9250 00576 // Are we handling the temperature correction bit properly? 00577 // Push accelerometer biases to hardware registers 00578 /* writeByte(MPU9250_ADDRESS, XA_OFFSET_H, data[0]); 00579 writeByte(MPU9250_ADDRESS, XA_OFFSET_L, data[1]); 00580 writeByte(MPU9250_ADDRESS, YA_OFFSET_H, data[2]); 00581 writeByte(MPU9250_ADDRESS, YA_OFFSET_L, data[3]); 00582 writeByte(MPU9250_ADDRESS, ZA_OFFSET_H, data[4]); 00583 writeByte(MPU9250_ADDRESS, ZA_OFFSET_L, data[5]); 00584 */ 00585 // Output scaled accelerometer biases for manual subtraction in the main program 00586 dest2[0] = (float)accel_bias[0]/(float)accelsensitivity; 00587 dest2[1] = (float)accel_bias[1]/(float)accelsensitivity; 00588 dest2[2] = (float)accel_bias[2]/(float)accelsensitivity; 00589 } 00590 00591 00592 // Accelerometer and gyroscope self test; check calibration wrt factory settings 00593 void MPU9250SelfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass 00594 { 00595 uint8_t rawData[6] = {0, 0, 0, 0, 0, 0}; 00596 uint8_t selfTest[6]; 00597 int16_t gAvg[3], aAvg[3], aSTAvg[3], gSTAvg[3]; 00598 float factoryTrim[6]; 00599 uint8_t FS = 0; 00600 00601 writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x00); // Set gyro sample rate to 1 kHz 00602 writeByte(MPU9250_ADDRESS, CONFIG, 0x02); // Set gyro sample rate to 1 kHz and DLPF to 92 Hz 00603 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 1<<FS); // Set full scale range for the gyro to 250 dps 00604 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, 0x02); // Set accelerometer rate to 1 kHz and bandwidth to 92 Hz 00605 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 1<<FS); // Set full scale range for the accelerometer to 2 g 00606 00607 for( int ii = 0; ii < 200; ii++) { // get average current values of gyro and acclerometer 00608 00609 readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array 00610 aAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00611 aAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00612 aAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00613 00614 readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array 00615 gAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00616 gAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00617 gAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00618 } 00619 00620 for (int ii =0; ii < 3; ii++) { // Get average of 200 values and store as average current readings 00621 aAvg[ii] /= 200; 00622 gAvg[ii] /= 200; 00623 } 00624 00625 // Configure the accelerometer for self-test 00626 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 0xE0); // Enable self test on all three axes and set accelerometer range to +/- 2 g 00627 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 0xE0); // Enable self test on all three axes and set gyro range to +/- 250 degrees/s 00628 wait(25); // Delay a while to let the device stabilize 00629 00630 for( int ii = 0; ii < 200; ii++) { // get average self-test values of gyro and acclerometer 00631 00632 readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array 00633 aSTAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00634 aSTAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00635 aSTAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00636 00637 readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array 00638 gSTAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value 00639 gSTAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; 00640 gSTAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 00641 } 00642 00643 for (int ii =0; ii < 3; ii++) { // Get average of 200 values and store as average self-test readings 00644 aSTAvg[ii] /= 200; 00645 gSTAvg[ii] /= 200; 00646 } 00647 00648 // Configure the gyro and accelerometer for normal operation 00649 writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 0x00); 00650 writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 0x00); 00651 wait(25); // Delay a while to let the device stabilize 00652 00653 // Retrieve accelerometer and gyro factory Self-Test Code from USR_Reg 00654 selfTest[0] = readByte(MPU9250_ADDRESS, SELF_TEST_X_ACCEL); // X-axis accel self-test results 00655 selfTest[1] = readByte(MPU9250_ADDRESS, SELF_TEST_Y_ACCEL); // Y-axis accel self-test results 00656 selfTest[2] = readByte(MPU9250_ADDRESS, SELF_TEST_Z_ACCEL); // Z-axis accel self-test results 00657 selfTest[3] = readByte(MPU9250_ADDRESS, SELF_TEST_X_GYRO); // X-axis gyro self-test results 00658 selfTest[4] = readByte(MPU9250_ADDRESS, SELF_TEST_Y_GYRO); // Y-axis gyro self-test results 00659 selfTest[5] = readByte(MPU9250_ADDRESS, SELF_TEST_Z_GYRO); // Z-axis gyro self-test results 00660 00661 // Retrieve factory self-test value from self-test code reads 00662 factoryTrim[0] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[0] - 1.0) )); // FT[Xa] factory trim calculation 00663 factoryTrim[1] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[1] - 1.0) )); // FT[Ya] factory trim calculation 00664 factoryTrim[2] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[2] - 1.0) )); // FT[Za] factory trim calculation 00665 factoryTrim[3] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[3] - 1.0) )); // FT[Xg] factory trim calculation 00666 factoryTrim[4] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[4] - 1.0) )); // FT[Yg] factory trim calculation 00667 factoryTrim[5] = (float)(2620/1<<FS)*(pow( 1.01 , ((float)selfTest[5] - 1.0) )); // FT[Zg] factory trim calculation 00668 00669 // Report results as a ratio of (STR - FT)/FT; the change from Factory Trim of the Self-Test Response 00670 // To get percent, must multiply by 100 00671 for (int i = 0; i < 3; i++) { 00672 destination[i] = 100.0*((float)(aSTAvg[i] - aAvg[i]))/factoryTrim[i]; // Report percent differences 00673 destination[i+3] = 100.0*((float)(gSTAvg[i] - gAvg[i]))/factoryTrim[i+3]; // Report percent differences 00674 } 00675 00676 } 00677 00678 00679 00680 // Implementation of Sebastian Madgwick's "...efficient orientation filter for... inertial/magnetic sensor arrays" 00681 // (see http://www.x-io.co.uk/category/open-source/ for examples and more details) 00682 // which fuses acceleration, rotation rate, and magnetic moments to produce a quaternion-based estimate of absolute 00683 // device orientation -- which can be converted to yaw, pitch, and roll. Useful for stabilizing quadcopters, etc. 00684 // The performance of the orientation filter is at least as good as conventional Kalman-based filtering algorithms 00685 // but is much less computationally intensive---it can be performed on a 3.3 V Pro Mini operating at 8 MHz! 00686 void MadgwickQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz, float mx, float my, float mz) 00687 { 00688 float q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3]; // short name local variable for readability 00689 float norm; 00690 float hx, hy, _2bx, _2bz; 00691 float s1, s2, s3, s4; 00692 float qDot1, qDot2, qDot3, qDot4; 00693 00694 // Auxiliary variables to avoid repeated arithmetic 00695 float _2q1mx; 00696 float _2q1my; 00697 float _2q1mz; 00698 float _2q2mx; 00699 float _4bx; 00700 float _4bz; 00701 float _2q1 = 2.0f * q1; 00702 float _2q2 = 2.0f * q2; 00703 float _2q3 = 2.0f * q3; 00704 float _2q4 = 2.0f * q4; 00705 float _2q1q3 = 2.0f * q1 * q3; 00706 float _2q3q4 = 2.0f * q3 * q4; 00707 float q1q1 = q1 * q1; 00708 float q1q2 = q1 * q2; 00709 float q1q3 = q1 * q3; 00710 float q1q4 = q1 * q4; 00711 float q2q2 = q2 * q2; 00712 float q2q3 = q2 * q3; 00713 float q2q4 = q2 * q4; 00714 float q3q3 = q3 * q3; 00715 float q3q4 = q3 * q4; 00716 float q4q4 = q4 * q4; 00717 00718 // Normalise accelerometer measurement 00719 norm = sqrt(ax * ax + ay * ay + az * az); 00720 if (norm == 0.0f) return; // handle NaN 00721 norm = 1.0f/norm; 00722 ax *= norm; 00723 ay *= norm; 00724 az *= norm; 00725 00726 // Normalise magnetometer measurement 00727 norm = sqrt(mx * mx + my * my + mz * mz); 00728 if (norm == 0.0f) return; // handle NaN 00729 norm = 1.0f/norm; 00730 mx *= norm; 00731 my *= norm; 00732 mz *= norm; 00733 00734 // Reference direction of Earth's magnetic field 00735 _2q1mx = 2.0f * q1 * mx; 00736 _2q1my = 2.0f * q1 * my; 00737 _2q1mz = 2.0f * q1 * mz; 00738 _2q2mx = 2.0f * q2 * mx; 00739 hx = mx * q1q1 - _2q1my * q4 + _2q1mz * q3 + mx * q2q2 + _2q2 * my * q3 + _2q2 * mz * q4 - mx * q3q3 - mx * q4q4; 00740 hy = _2q1mx * q4 + my * q1q1 - _2q1mz * q2 + _2q2mx * q3 - my * q2q2 + my * q3q3 + _2q3 * mz * q4 - my * q4q4; 00741 _2bx = sqrt(hx * hx + hy * hy); 00742 _2bz = -_2q1mx * q3 + _2q1my * q2 + mz * q1q1 + _2q2mx * q4 - mz * q2q2 + _2q3 * my * q4 - mz * q3q3 + mz * q4q4; 00743 _4bx = 2.0f * _2bx; 00744 _4bz = 2.0f * _2bz; 00745 00746 // Gradient decent algorithm corrective step 00747 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); 00748 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); 00749 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); 00750 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); 00751 norm = sqrt(s1 * s1 + s2 * s2 + s3 * s3 + s4 * s4); // normalise step magnitude 00752 norm = 1.0f/norm; 00753 s1 *= norm; 00754 s2 *= norm; 00755 s3 *= norm; 00756 s4 *= norm; 00757 00758 // Compute rate of change of quaternion 00759 qDot1 = 0.5f * (-q2 * gx - q3 * gy - q4 * gz) - beta * s1; 00760 qDot2 = 0.5f * (q1 * gx + q3 * gz - q4 * gy) - beta * s2; 00761 qDot3 = 0.5f * (q1 * gy - q2 * gz + q4 * gx) - beta * s3; 00762 qDot4 = 0.5f * (q1 * gz + q2 * gy - q3 * gx) - beta * s4; 00763 00764 // Integrate to yield quaternion 00765 q1 += qDot1 * deltat; 00766 q2 += qDot2 * deltat; 00767 q3 += qDot3 * deltat; 00768 q4 += qDot4 * deltat; 00769 norm = sqrt(q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4); // normalise quaternion 00770 norm = 1.0f/norm; 00771 q[0] = q1 * norm; 00772 q[1] = q2 * norm; 00773 q[2] = q3 * norm; 00774 q[3] = q4 * norm; 00775 00776 } 00777 00778 00779 00780 // Similar to Madgwick scheme but uses proportional and integral filtering on the error between estimated reference vectors and 00781 // measured ones. 00782 void MahonyQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz, float mx, float my, float mz) 00783 { 00784 float q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3]; // short name local variable for readability 00785 float norm; 00786 float hx, hy, bx, bz; 00787 float vx, vy, vz, wx, wy, wz; 00788 float ex, ey, ez; 00789 float pa, pb, pc; 00790 00791 // Auxiliary variables to avoid repeated arithmetic 00792 float q1q1 = q1 * q1; 00793 float q1q2 = q1 * q2; 00794 float q1q3 = q1 * q3; 00795 float q1q4 = q1 * q4; 00796 float q2q2 = q2 * q2; 00797 float q2q3 = q2 * q3; 00798 float q2q4 = q2 * q4; 00799 float q3q3 = q3 * q3; 00800 float q3q4 = q3 * q4; 00801 float q4q4 = q4 * q4; 00802 00803 // Normalise accelerometer measurement 00804 norm = sqrt(ax * ax + ay * ay + az * az); 00805 if (norm == 0.0f) return; // handle NaN 00806 norm = 1.0f / norm; // use reciprocal for division 00807 ax *= norm; 00808 ay *= norm; 00809 az *= norm; 00810 00811 // Normalise magnetometer measurement 00812 norm = sqrt(mx * mx + my * my + mz * mz); 00813 if (norm == 0.0f) return; // handle NaN 00814 norm = 1.0f / norm; // use reciprocal for division 00815 mx *= norm; 00816 my *= norm; 00817 mz *= norm; 00818 00819 // Reference direction of Earth's magnetic field 00820 hx = 2.0f * mx * (0.5f - q3q3 - q4q4) + 2.0f * my * (q2q3 - q1q4) + 2.0f * mz * (q2q4 + q1q3); 00821 hy = 2.0f * mx * (q2q3 + q1q4) + 2.0f * my * (0.5f - q2q2 - q4q4) + 2.0f * mz * (q3q4 - q1q2); 00822 bx = sqrt((hx * hx) + (hy * hy)); 00823 bz = 2.0f * mx * (q2q4 - q1q3) + 2.0f * my * (q3q4 + q1q2) + 2.0f * mz * (0.5f - q2q2 - q3q3); 00824 00825 // Estimated direction of gravity and magnetic field 00826 vx = 2.0f * (q2q4 - q1q3); 00827 vy = 2.0f * (q1q2 + q3q4); 00828 vz = q1q1 - q2q2 - q3q3 + q4q4; 00829 wx = 2.0f * bx * (0.5f - q3q3 - q4q4) + 2.0f * bz * (q2q4 - q1q3); 00830 wy = 2.0f * bx * (q2q3 - q1q4) + 2.0f * bz * (q1q2 + q3q4); 00831 wz = 2.0f * bx * (q1q3 + q2q4) + 2.0f * bz * (0.5f - q2q2 - q3q3); 00832 00833 // Error is cross product between estimated direction and measured direction of gravity 00834 ex = (ay * vz - az * vy) + (my * wz - mz * wy); 00835 ey = (az * vx - ax * vz) + (mz * wx - mx * wz); 00836 ez = (ax * vy - ay * vx) + (mx * wy - my * wx); 00837 if (Ki > 0.0f) 00838 { 00839 eInt[0] += ex; // accumulate integral error 00840 eInt[1] += ey; 00841 eInt[2] += ez; 00842 } 00843 else 00844 { 00845 eInt[0] = 0.0f; // prevent integral wind up 00846 eInt[1] = 0.0f; 00847 eInt[2] = 0.0f; 00848 } 00849 00850 // Apply feedback terms 00851 gx = gx + Kp * ex + Ki * eInt[0]; 00852 gy = gy + Kp * ey + Ki * eInt[1]; 00853 gz = gz + Kp * ez + Ki * eInt[2]; 00854 00855 // Integrate rate of change of quaternion 00856 pa = q2; 00857 pb = q3; 00858 pc = q4; 00859 q1 = q1 + (-q2 * gx - q3 * gy - q4 * gz) * (0.5f * deltat); 00860 q2 = pa + (q1 * gx + pb * gz - pc * gy) * (0.5f * deltat); 00861 q3 = pb + (q1 * gy - pa * gz + pc * gx) * (0.5f * deltat); 00862 q4 = pc + (q1 * gz + pa * gy - pb * gx) * (0.5f * deltat); 00863 00864 // Normalise quaternion 00865 norm = sqrt(q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4); 00866 norm = 1.0f / norm; 00867 q[0] = q1 * norm; 00868 q[1] = q2 * norm; 00869 q[2] = q3 * norm; 00870 q[3] = q4 * norm; 00871 00872 } 00873 }; 00874 #endif
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