Speed testing IMUs
Dependencies: MadgwickAHRS mbed
Fork of IMU_serial by
Diff: MPU9250.h
- Revision:
- 0:80a695ae3cc3
- Child:
- 3:c1902ecb30a7
diff -r 000000000000 -r 80a695ae3cc3 MPU9250.h --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MPU9250.h Wed Sep 28 23:59:57 2016 +0000 @@ -0,0 +1,1030 @@ +/* +TODO: +add configuration function: +loop through mux +if imu + append imu to a list + ... + ... +if list > 0 + return something good + +add config output function + + + +*/ + + +#ifndef MPU9250_H +#define MPU9250_H + +#include "mbed.h" +#include "math.h" +#include "MadgwickAHRS.h" + +// 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 +// above document; the MPU9250 and MPU9150 are virtually identical but the latter has a different register map +// +//Magnetometer Registers +#define AK8963_ADDRESS 0x0C<<1 +#define WHO_AM_I_AK8963 0x00 // should return 0x48 +#define INFO 0x01 +#define AK8963_ST1 0x02 // data ready status bit 0 +#define AK8963_XOUT_L 0x03 // data +#define AK8963_XOUT_H 0x04 +#define AK8963_YOUT_L 0x05 +#define AK8963_YOUT_H 0x06 +#define AK8963_ZOUT_L 0x07 +#define AK8963_ZOUT_H 0x08 +#define AK8963_ST2 0x09 // Data overflow bit 3 and data read error status bit 2 +#define AK8963_CNTL 0x0A // Power down (0000), single-measurement (0001), self-test (1000) and Fuse ROM (1111) modes on bits 3:0 +#define AK8963_ASTC 0x0C // Self test control +#define AK8963_I2CDIS 0x0F // I2C disable +#define AK8963_ASAX 0x10 // Fuse ROM x-axis sensitivity adjustment value +#define AK8963_ASAY 0x11 // Fuse ROM y-axis sensitivity adjustment value +#define AK8963_ASAZ 0x12 // Fuse ROM z-axis sensitivity adjustment value + +#define SELF_TEST_X_GYRO 0x00 +#define SELF_TEST_Y_GYRO 0x01 +#define SELF_TEST_Z_GYRO 0x02 + +/*#define X_FINE_GAIN 0x03 // [7:0] fine gain +#define Y_FINE_GAIN 0x04 +#define Z_FINE_GAIN 0x05 +#define XA_OFFSET_H 0x06 // User-defined trim values for accelerometer +#define XA_OFFSET_L_TC 0x07 +#define YA_OFFSET_H 0x08 +#define YA_OFFSET_L_TC 0x09 +#define ZA_OFFSET_H 0x0A +#define ZA_OFFSET_L_TC 0x0B */ + +#define SELF_TEST_X_ACCEL 0x0D +#define SELF_TEST_Y_ACCEL 0x0E +#define SELF_TEST_Z_ACCEL 0x0F + +#define SELF_TEST_A 0x10 + +#define XG_OFFSET_H 0x13 // User-defined trim values for gyroscope +#define XG_OFFSET_L 0x14 +#define YG_OFFSET_H 0x15 +#define YG_OFFSET_L 0x16 +#define ZG_OFFSET_H 0x17 +#define ZG_OFFSET_L 0x18 +#define SMPLRT_DIV 0x19 +#define CONFIG 0x1A +#define GYRO_CONFIG 0x1B +#define ACCEL_CONFIG 0x1C +#define ACCEL_CONFIG2 0x1D +#define LP_ACCEL_ODR 0x1E +#define WOM_THR 0x1F + +#define MOT_DUR 0x20 // Duration counter threshold for motion interrupt generation, 1 kHz rate, LSB = 1 ms +#define ZMOT_THR 0x21 // Zero-motion detection threshold bits [7:0] +#define ZRMOT_DUR 0x22 // Duration counter threshold for zero motion interrupt generation, 16 Hz rate, LSB = 64 ms + +#define FIFO_EN 0x23 +#define I2C_MST_CTRL 0x24 +#define I2C_SLV0_ADDR 0x25 +#define I2C_SLV0_REG 0x26 +#define I2C_SLV0_CTRL 0x27 +#define I2C_SLV1_ADDR 0x28 +#define I2C_SLV1_REG 0x29 +#define I2C_SLV1_CTRL 0x2A +#define I2C_SLV2_ADDR 0x2B +#define I2C_SLV2_REG 0x2C +#define I2C_SLV2_CTRL 0x2D +#define I2C_SLV3_ADDR 0x2E +#define I2C_SLV3_REG 0x2F +#define I2C_SLV3_CTRL 0x30 +#define I2C_SLV4_ADDR 0x31 +#define I2C_SLV4_REG 0x32 +#define I2C_SLV4_DO 0x33 +#define I2C_SLV4_CTRL 0x34 +#define I2C_SLV4_DI 0x35 +#define I2C_MST_STATUS 0x36 +#define INT_PIN_CFG 0x37 +#define INT_ENABLE 0x38 +#define DMP_INT_STATUS 0x39 // Check DMP interrupt +#define INT_STATUS 0x3A +#define ACCEL_XOUT_H 0x3B +#define ACCEL_XOUT_L 0x3C +#define ACCEL_YOUT_H 0x3D +#define ACCEL_YOUT_L 0x3E +#define ACCEL_ZOUT_H 0x3F +#define ACCEL_ZOUT_L 0x40 +#define TEMP_OUT_H 0x41 +#define TEMP_OUT_L 0x42 +#define GYRO_XOUT_H 0x43 +#define GYRO_XOUT_L 0x44 +#define GYRO_YOUT_H 0x45 +#define GYRO_YOUT_L 0x46 +#define GYRO_ZOUT_H 0x47 +#define GYRO_ZOUT_L 0x48 +#define EXT_SENS_DATA_00 0x49 +#define EXT_SENS_DATA_01 0x4A +#define EXT_SENS_DATA_02 0x4B +#define EXT_SENS_DATA_03 0x4C +#define EXT_SENS_DATA_04 0x4D +#define EXT_SENS_DATA_05 0x4E +#define EXT_SENS_DATA_06 0x4F +#define EXT_SENS_DATA_07 0x50 +#define EXT_SENS_DATA_08 0x51 +#define EXT_SENS_DATA_09 0x52 +#define EXT_SENS_DATA_10 0x53 +#define EXT_SENS_DATA_11 0x54 +#define EXT_SENS_DATA_12 0x55 +#define EXT_SENS_DATA_13 0x56 +#define EXT_SENS_DATA_14 0x57 +#define EXT_SENS_DATA_15 0x58 +#define EXT_SENS_DATA_16 0x59 +#define EXT_SENS_DATA_17 0x5A +#define EXT_SENS_DATA_18 0x5B +#define EXT_SENS_DATA_19 0x5C +#define EXT_SENS_DATA_20 0x5D +#define EXT_SENS_DATA_21 0x5E +#define EXT_SENS_DATA_22 0x5F +#define EXT_SENS_DATA_23 0x60 +#define MOT_DETECT_STATUS 0x61 +#define I2C_SLV0_DO 0x63 +#define I2C_SLV1_DO 0x64 +#define I2C_SLV2_DO 0x65 +#define I2C_SLV3_DO 0x66 +#define I2C_MST_DELAY_CTRL 0x67 +#define SIGNAL_PATH_RESET 0x68 +#define MOT_DETECT_CTRL 0x69 +#define USER_CTRL 0x6A // Bit 7 enable DMP, bit 3 reset DMP +#define PWR_MGMT_1 0x6B // Device defaults to the SLEEP mode +#define PWR_MGMT_2 0x6C +#define DMP_BANK 0x6D // Activates a specific bank in the DMP +#define DMP_RW_PNT 0x6E // Set read/write pointer to a specific start address in specified DMP bank +#define DMP_REG 0x6F // Register in DMP from which to read or to which to write +#define DMP_REG_1 0x70 +#define DMP_REG_2 0x71 +#define FIFO_COUNTH 0x72 +#define FIFO_COUNTL 0x73 +#define FIFO_R_W 0x74 +#define WHO_AM_I_MPU9250 0x75 // Should return 0x71 +#define XA_OFFSET_H 0x77 +#define XA_OFFSET_L 0x78 +#define YA_OFFSET_H 0x7A +#define YA_OFFSET_L 0x7B +#define ZA_OFFSET_H 0x7D +#define ZA_OFFSET_L 0x7E + +// Using the MSENSR-9250 breakout board, ADO is set to 0 +// Seven-bit device address is 110100 for ADO = 0 and 110101 for ADO = 1 +//mbed uses the eight-bit device address, so shift seven-bit addresses left by one! +#define ADO 0 +#if ADO +#define MPU9250_ADDRESS 0x69<<1 // Device address when ADO = 1 +#else +#define MPU9250_ADDRESS 0x68<<1 // Device address when ADO = 0 +#endif + +// Set initial input parameters +enum Ascale { + AFS_2G = 0, + AFS_4G, + AFS_8G, + AFS_16G +}; + +enum Gscale { + GFS_250DPS = 0, + GFS_500DPS, + GFS_1000DPS, + GFS_2000DPS +}; + +enum Mscale { + MFS_14BITS = 0, // 0.6 mG per LSB + MFS_16BITS // 0.15 mG per LSB +}; + +uint8_t Ascale = AFS_2G; // AFS_2G, AFS_4G, AFS_8G, AFS_16G +uint8_t Gscale = GFS_250DPS; // GFS_250DPS, GFS_500DPS, GFS_1000DPS, GFS_2000DPS +uint8_t Mscale = MFS_16BITS; // MFS_14BITS or MFS_16BITS, 14-bit or 16-bit magnetometer resolution +uint8_t Mmode = 0x06; // Either 8 Hz 0x02) or 100 Hz (0x06) magnetometer data ODR +float aRes, gRes, mRes; // scale resolutions per LSB for the sensors + +//Set up I2C, (SDA,SCL) +I2C i2c(I2C_SDA, I2C_SCL); + +DigitalOut myled(LED1); + +// Pin definitions +int intPin = 12; // These can be changed, 2 and 3 are the Arduinos ext int pins + +float SelfTest[6]; + +int delt_t = 0; // used to control display output rate +int count = 0; // used to control display output rate + +// parameters for 6 DoF sensor fusion calculations +float PI = 3.14159265358979323846f; +float GyroMeasError = PI * (60.0f / 180.0f); // gyroscope measurement error in rads/s (start at 60 deg/s), then reduce after ~10 s to 3 +//float beta = sqrt(3.0f / 4.0f) * GyroMeasError; // compute beta +float GyroMeasDrift = PI * (1.0f / 180.0f); // gyroscope measurement drift in rad/s/s (start at 0.0 deg/s/s) +float zeta = sqrt(3.0f / 4.0f) * GyroMeasDrift; // compute zeta, the other free parameter in the Madgwick scheme usually set to a small or zero value +#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 +#define Ki 0.0f + + + +class MPU9250 +{ + +protected: + +public: + int16_t accelCount[3]; // Stores the 16-bit signed accelerometer sensor output + int16_t gyroCount[3]; // Stores the 16-bit signed gyro sensor output + int16_t magCount[3]; // Stores the 16-bit signed magnetometer sensor output + float ax, ay, az, gx, gy, gz, mx, my, mz; // variables to hold latest sensor data values + float magCalibration[3]; + float magbias[3]; // Factory mag calibration and mag bias + float gyroBias[3]; + float accelBias[3]; // Bias corrections for gyro and accelerometer + int16_t tempCount; // Stores the real internal chip temperature in degrees Celsius + float temperature; + float pitch, yaw, roll; + float deltat; // integration interval for both filter schemes + int lastUpdate; + int firstUpdate; + int Now; // used to calculate integration interval + float q[4]; // vector to hold quaternion + float eInt[3]; // vector to hold integral error for Mahony method + uint32_t checksum; + + MPU9250() { + ax=ay=az=gx=gy=gz=mx=my=mz=0.0; + for (int i = 0; i < 3; i++) { + magCalibration[i] = 0.0; + magbias[i] = 0.0; + gyroBias[i] = 0.0; + accelBias[i] = 0.0; + eInt[i] = 0.0f; + } // end of for + q[0] = 1.0f; + q[1] = 0.0f; + q[2] = 0.0f; + q[3] = 0.0f; + lastUpdate = 0, firstUpdate = 0, Now = 0; + deltat = 0.0f; + } // end of initalizer + +//=================================================================================================================== +//====== Set of useful function to access acceleratio, gyroscope, and temperature data +//=================================================================================================================== + + void writeByte(uint8_t address, uint8_t subAddress, uint8_t data) { + char data_write[2]; + data_write[0] = subAddress; + data_write[1] = data; + i2c.write(address, data_write, 2, 0); + } + + + void selfTest(Serial &pc , bool show = false) { + resetMPU9250(); // Reset registers to default in preparation for device calibration + MPU9250SelfTest(SelfTest); // Start by performing self test and reporting values + if (show) { + pc.printf("x-axis self test: acceleration trim within : %f % of factory value\n\r", SelfTest[0]); + pc.printf("y-axis self test: acceleration trim within : %f % of factory value\n\r", SelfTest[1]); + pc.printf("z-axis self test: acceleration trim within : %f % of factory value\n\r", SelfTest[2]); + pc.printf("x-axis self test: gyration trim within : %f % of factory value\n\r", SelfTest[3]); + pc.printf("y-axis self test: gyration trim within : %f % of factory value\n\r", SelfTest[4]); + pc.printf("z-axis self test: gyration trim within : %f % of factory value\n\r", SelfTest[5]); + } + //calibrateMPU9250(gyroBias, accelBias); // Calibrate gyro and accelerometers, load biases in bias registers + if(show) { + pc.printf("x gyro bias = %f\n\r", gyroBias[0]); + pc.printf("y gyro bias = %f\n\r", gyroBias[1]); + pc.printf("z gyro bias = %f\n\r", gyroBias[2]); + pc.printf("x accel bias = %f\n\r", accelBias[0]); + pc.printf("y accel bias = %f\n\r", accelBias[1]); + pc.printf("z accel bias = %f\n\r", accelBias[2]); + } + } + + + void config(Serial &pc, bool show = false) { + initMPU9250(); + if (show) + pc.printf("MPU9250 initialized for active data mode....\n\r"); // Initialize device for active mode read of acclerometer, gyroscope, and temperature + initAK8963(magCalibration); + if(show) { + pc.printf("AK8963 initialized for active data mode....\n\r"); // Initialize device for active mode read of magnetometer + pc.printf("Accelerometer full-scale range = %f g\n\r", 2.0f*(float)(1<<Ascale)); + pc.printf("Gyroscope full-scale range = %f deg/s\n\r", 250.0f*(float)(1<<Gscale)); + if(Mscale == 0) pc.printf("Magnetometer resolution = 14 bits\n\r"); + if(Mscale == 1) pc.printf("Magnetometer resolution = 16 bits\n\r"); + if(Mmode == 2) pc.printf("Magnetometer ODR = 8 Hz\n\r"); + if(Mmode == 6) pc.printf("Magnetometer ODR = 100 Hz\n\r"); + pc.printf("mag calibration: \r\nx:\t%f\r\ny:\t%f\r\nz:\t%f\r\n", magbias[0], magbias[1], magbias[2]); + } + } + + + void sensitivity(Serial &pc, bool show = false) { + getAres(); // Get accelerometer sensitivity + getGres(); // Get gyro sensitivity + getMres(); // Get magnetometer sensitivity + if (show) { + pc.printf("Accelerometer sensitivity is %f LSB/g \n\r", 1.0f/aRes); + pc.printf("Gyroscope sensitivity is %f LSB/deg/s \n\r", 1.0f/gRes); + pc.printf("Magnetometer sensitivity is %f LSB/G \n\r", 1.0f/mRes); + } + } + + + char readByte(uint8_t address, uint8_t subAddress) { + char data[1]; // `data` will store the register data + char data_write[1]; + data_write[0] = subAddress; + i2c.write(address, data_write, 1, 1); // no stop + i2c.read(address, data, 1, 0); + return data[0]; + } + + + void readBytes(uint8_t address, uint8_t subAddress, uint8_t count, uint8_t * dest) { + char data[14]; + char data_write[1]; + data_write[0] = subAddress; + i2c.write(address, data_write, 1, 1); // no stop + i2c.read(address, data, count, 0); + for(int ii = 0; ii < count; ii++) { + dest[ii] = data[ii]; + } + } + + + void getMres() { + 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 getGres() { + switch (Gscale) { + // Possible gyro scales (and their register bit settings) are: + // 250 DPS (00), 500 DPS (01), 1000 DPS (10), and 2000 DPS (11). + // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value: + case GFS_250DPS: + gRes = 250.0/32768.0; + break; + case GFS_500DPS: + gRes = 500.0/32768.0; + break; + case GFS_1000DPS: + gRes = 1000.0/32768.0; + break; + case GFS_2000DPS: + gRes = 2000.0/32768.0; + break; + } + } + + + void getAres() { + switch (Ascale) { + // Possible accelerometer scales (and their register bit settings) are: + // 2 Gs (00), 4 Gs (01), 8 Gs (10), and 16 Gs (11). + // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value: + case AFS_2G: + aRes = 2.0/32768.0; + break; + case AFS_4G: + aRes = 4.0/32768.0; + break; + case AFS_8G: + aRes = 8.0/32768.0; + break; + case AFS_16G: + aRes = 16.0/32768.0; + break; + } + } + + + void readAccelData() { + 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 + ax = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value + ay = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; + az = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; + } + + void readGyroData() { + 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 + gx = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value + gy = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ; + gz = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; + } + + void readMagData() { + 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 + mx = (int16_t)(((int16_t)rawData[1] << 8) | rawData[0]) ; // Turn the MSB and LSB into a signed 16-bit value + my = (int16_t)(((int16_t)rawData[3] << 8) | rawData[2]) ; // Data stored as little Endian + mz = (int16_t)(((int16_t)rawData[5] << 8) | rawData[4]) ; + } + } + } + + void readimu() { + readAccelData(); + ax = ax*aRes - accelBias[0]; + ay = ay*aRes - accelBias[1]; + az = az*aRes - accelBias[2]; + + readGyroData(); + gx = gx*gRes - gyroBias[0]; + gy = gy*gRes - gyroBias[1]; + gz = gz*gRes - gyroBias[2]; + + // Calculate the magnetometer values in milliGauss + // Include factory calibration per data sheet and user environmental corrections + readMagData(); + mx = mx*mRes*magCalibration[0] - magbias[0]; + my = my*mRes*magCalibration[1] - magbias[1]; + mz = mz*mRes*magCalibration[2] - magbias[2]; + + checksum = 0; + checksum += int(1000*ax) + int(1000*ay) + int(1000*az) +int(gx) + int(gy) + int(gz) +int(mx) + int(my) + int(mz); + + }// end of read IMUData() + + int16_t readTempData() { + 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 + } + + + void resetMPU9250() { + // reset device + writeByte(MPU9250_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device + wait(0.1); + } + + void 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 initMPU9250() { + // 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); + writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] + writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c & ~0x18); // Clear AFS bits [4:3] + writeByte(MPU9250_ADDRESS, GYRO_CONFIG, c | Gscale << 3); // Set full scale range for the gyro + + // Set accelerometer configuration + c = readByte(MPU9250_ADDRESS, ACCEL_CONFIG); + writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] + writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c & ~0x18); // Clear AFS bits [4:3] + writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, c | Ascale << 3); // Set full scale range for the accelerometer + + // 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); + writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, c & ~0x0F); // Clear accel_fchoice_b (bit 3) and A_DLPFG (bits [2:0]) + writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, c | 0x03); // Set accelerometer rate to 1 kHz and bandwidth to 41 Hz + + // 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 calibrateMag(float * dest1, float * dest2, Serial &pc) + void calibrateMag(Serial &pc) { + uint16_t ii = 0, sample_count = 0; + //int32_t mag_bias[3] = {0, 0, 0}; + int32_t mag_scale[3] = {0, 0, 0}; + int16_t mag_max[3] = {0x8000, 0x8000, 0x8000}; + int16_t mag_min[3] = {0x7FFF, 0x7FFF, 0x7FFF}; + int16_t mag_temp[3] = {0, 0, 0}; + pc.printf("Pre-Mag Calibration: \r\nx:\t%f\r\ny:\t%f\r\nz:\t%f\r\n", magbias[0], magbias[1], magbias[2]); + pc.printf("Mag Calibration: Wave device in a figure eight until done!\n"); + wait(4); + + sample_count = 500; + for(ii = 0; ii < sample_count; ii++) { + //readMagData(mag_temp); // Read the mag data + for (int jj = 0; jj < 3; jj++) { + if(mag_temp[jj] > mag_max[jj]) mag_max[jj] = mag_temp[jj]; + if(mag_temp[jj] < mag_min[jj]) mag_min[jj] = mag_temp[jj]; + }// end of inner for + wait(.035); // at 8 Hz ODR, new mag data is available every 125 ms + pc.printf("%d\t%d\t%d\r\n", mag_temp[0], mag_temp[1], mag_temp[2]); + }// end of outer for + wait(1); + pc.printf("%d\t%d\t%d\t%d\t%d\t%d\r\n", mag_min[0], mag_max[0], mag_min[1], mag_max[1], mag_min[2], mag_max[2]); + wait(10); + // Get hard iron correction + magbias[0] = (mag_max[0] + mag_min[0])/2; // get average x mag bias in counts + magbias[1] = (mag_max[1] + mag_min[1])/2; // get average y mag bias in counts + magbias[2] = (mag_max[2] + mag_min[2])/2; // get average z mag bias in counts + + //dest1[0] = (float) mag_bias[0]*mRes*MPU9250magCalibration[0]; // save mag biases in G for main program + //dest1[1] = (float) mag_bias[1]*mRes*MPU9250magCalibration[1]; + //dest1[2] = (float) mag_bias[2]*mRes*MPU9250magCalibration[2]; + + // Get soft iron correction estimate + mag_scale[0] = (mag_max[0] - mag_min[0])/2; // get average x axis max chord length in counts + mag_scale[1] = (mag_max[1] - mag_min[1])/2; // get average y axis max chord length in counts + mag_scale[2] = (mag_max[2] - mag_min[2])/2; // get average z axis max chord length in counts + + float avg_rad = mag_scale[0] + mag_scale[1] + mag_scale[2]; + avg_rad /= 3.0; + + //dest2[0] = avg_rad/((float)mag_scale[0]); + //dest2[1] = avg_rad/((float)mag_scale[1]); + //dest2[2] = avg_rad/((float)mag_scale[2]); + pc.printf("Post-Mag Calibration: \r\nx:\t%f\r\ny:\t%f\r\nz:\t%f\r\n", magbias[0], magbias[1], magbias[2]); + pc.printf("Mag Calibration done!\n"); + }// end of calibrateMag + + // 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 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}; + + // 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. + + int32_t accel_bias_reg[3] = {0, 0, 0}; // A place to hold the factory accelerometer trim biases + 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; + } + + + // Accelerometer and gyroscope self test; check calibration wrt factory settings + void 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 + wait_ms(25); // 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); + wait_ms(25); // 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 + } + + } + + + + // 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 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; + + } + + + // Similar to Madgwick scheme but uses proportional and integral filtering on the error between estimated reference vectors and + // measured ones. + void 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; + + } +}; +#endif \ No newline at end of file