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Class of MPU9250
Dependencies: AHRS_fillter mbed
Fork of MPU9250AHRS by
Diff: MPU9250.cpp
- Revision:
- 6:5665d427bceb
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MPU9250.cpp Wed Jan 20 02:34:07 2016 +0000 @@ -0,0 +1,699 @@ +#include "MPU9250.h" + + +MPU9250::MPU9250(PinName sda, PinName scl, PinName tx, PinName rx, int address) : i2c(sda, scl), pc(tx,rx) +{ + if(address == 0) + MPU9250_ADDRESS = MPU9250_ADDRESS_68; + else if(address == 1) MPU9250_ADDRESS = MPU9250_ADDRESS_69; + else { + printf("Wrong Address\n"); + while(1); + } + + i2c.frequency(400000); + + for(int i=0; i<=3; i++) { + magCalibration[i] = 0; + magbias[i] = 0; + gyroBias[i] = 0; + accelBias[i] = 0; + } + Mmode = 0x06; // Either 8 Hz 0x02) or 100 Hz (0x06) magnetometer data ODR +} + +void MPU9250::Start() +{ + whoami = readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250); // Read WHO_AM_I register for MPU-9250 + pc.printf("I AM 0x%x\n\r", whoami); + pc.printf("I SHOULD BE 0x71\n\r"); + + if (whoami == 0x71) { // WHO_AM_I should always be 0x68 + pc.printf("MPU9250 WHO_AM_I is 0x%x\n\r", whoami); + pc.printf("MPU9250 is online...\n\r"); + wait(1); + + resetMPU9250(); // Reset registers to default in preparation for device calibration + MPU9250SelfTest(); // Start by performing self test and reporting values + /*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(); // Calibrate gyro and accelerometers, load biases in bias registers + /*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]);*/ + wait(2); + initMPU9250(); + pc.printf("MPU9250 initialized for active data mode....\n\r"); // Initialize device for active mode read of acclerometer, gyroscope, and temperature + initAK8963(); + pc.printf("AK8963 initialized for active data mode....\n\r"); // Initialize device for active mode read of magnetometer + + whoami = readByte(AK8963_ADDRESS, WHO_AM_I_AK8963); // Read WHO_AM_I register for MPU-9250 + pc.printf("I AM 0x%x\n\r", whoami); + pc.printf("I SHOULD BE 0x48\n\r"); + if(whoami != 0x48) { + while(1); + } + /*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");*/ + wait(1); + } else { + pc.printf("Could not connect to MPU9250: \n\r"); + pc.printf("%#x \n", whoami); + + while(1) ; // Loop forever if communication doesn't happen + } + + + getAres(); // Get accelerometer sensitivity + getGres(); // Get gyro sensitivity + getMres(); // Get magnetometer sensitivity + /*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);*/ + + MagCal(); +} + +void MPU9250::ReadRawAccGyroMag() +{ + // If intPin goes high, all data registers have new data + if(readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01) { // On interrupt, check if data ready interrupt + + readAccelData(); // Read the x/y/z adc values + AccelXYZCal(); + // Now we'll calculate the accleration value into actual g's + /*ax = (float)accelCount[0]*aRes - accelBias[0]; // get actual g value, this depends on scale being set + ay = (float)accelCount[1]*aRes - accelBias[1]; + az = (float)accelCount[2]*aRes - accelBias[2];*/ + + readGyroData(); // Read the x/y/z adc values + GyroXYZCal(); + // Calculate the gyro value into actual degrees per second + /*gx = (float)gyroCount[0]*gRes - gyroBias[0]; // get actual gyro value, this depends on scale being set + gy = (float)gyroCount[1]*gRes - gyroBias[1]; + gz = (float)gyroCount[2]*gRes - gyroBias[2];*/ + + readMagData(); // Read the x/y/z adc values + MagXYZCal(); + /*mx = ((float)magCount[0]-xmin)*magCalibration[0] + magbias[0]; // get actual magnetometer value, this depends on scale being set + my = ((float)magCount[1]-ymin)*magCalibration[1] + magbias[1]; + mz = ((float)magCount[2]-zmin)*magCalibration[2] + magbias[2];*/ + } +} + +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::setMres() +{ + 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 MPU9250::setGres() +{ + 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 MPU9250::setAres() +{ + 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 MPU9250::getMres() +{ + Mscale = MFS_16BITS; // MFS_14BITS or MFS_16BITS, 14-bit or 16-bit magnetometer resolution +} + + +void MPU9250::getGres() +{ + Gscale = GFS_250DPS; // GFS_250DPS, GFS_500DPS, GFS_1000DPS, GFS_2000DPS +} + +void MPU9250::getAres() +{ + Ascale = AFS_2G; // AFS_2G, AFS_4G, AFS_8G, AFS_16G +} + +void MPU9250::MagCal() +{ + printf("START scan mag\n\r\n\r\n\r"); + + //Assign random value before calibrate + /*xmax = -4914.0f; + xmin = 4914.0f; + + ymax = -4914.0; + ymin = 4914.0f; + + zmax = -4914.0; + zmin = 4914.0f; + + change=false; + + while(1) { + readMagData(magCount); + + if(magCount[0]<xmin) { + xmin = magCount[0]; + change = true; + } + if(magCount[0]>xmax) { + xmax = magCount[0]; + change = true; + } + + if(magCount[1]<ymin) { + ymin = magCount[1]; + change = true; + } + if(magCount[1]>ymax) { + ymax = magCount[1]; + change = true; + } + + + if(magCount[2]<zmin) { + zmin = magCount[2]; + change = true; + } + if(magCount[2]>zmax) { + zmax = magCount[2]; + change = true; + } + + if(change==true) { + printf("Mx Max= %f Min= %f\n\r",xmax,xmin); + printf("My Max= %f Min= %f\n\r",ymax,ymin); + printf("Mz Max= %f Min= %f\n\r",zmax,zmin); + change=false; + }*/ + + //Out of Calibration loop + /*if(button==1) { + while(button==1); + break; + }*/ + //} + + + xmax = 188.000000; + xmin = -316.000000; + ymax = 485.000000; + ymin = -26.000000; + zmax = 165.000000; + xmin = -230.000000; + + magbias[0] = -1.0; + magbias[1] = -1.0; + magbias[2] = -1.0; + + magCalibration[0] = 2.0f / (xmax -xmin); + magCalibration[1] = 2.0f / (ymax -ymin); + magCalibration[2] = 2.0f / (zmax -zmin); + + printf("mag[0] %f",magbias[0]); + printf("mag[1] %f",magbias[1]); + printf("mag[2] %f\n\r",magbias[2]); +} + +void MPU9250::AccelXYZCal() +{ + ax = (float)accelCount[0]*aRes - accelBias[0]; // get actual g value, this depends on scale being set + ay = (float)accelCount[1]*aRes - accelBias[1]; + az = (float)accelCount[2]*aRes - accelBias[2]; +} + +void MPU9250::GyroXYZCal() +{ + gx = (float)gyroCount[0]*gRes - gyroBias[0]; // get actual gyro value, this depends on scale being set + gy = (float)gyroCount[1]*gRes - gyroBias[1]; + gz = (float)gyroCount[2]*gRes - gyroBias[2]; +} + +void MPU9250::MagXYZCal() +{ + mx = ((float)magCount[0]-xmin)*magCalibration[0] + magbias[0]; // get actual magnetometer value, this depends on scale being set + my = ((float)magCount[1]-ymin)*magCalibration[1] + magbias[1]; + mz = ((float)magCount[2]-zmin)*magCalibration[2] + magbias[2]; +} + + +void MPU9250::readAccelData() +{ + float destination[3] = {0,0,0}; + 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]) ; + + for(int i=0; i<=2; i++) + accelCount[i] = (float)destination[i]; +} + +void MPU9250::readGyroData() +{ + float destination[3] = {0,0,0}; + 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]) ; + + for(int i=0; i<=2; i++) + gyroCount[i] = (float)destination[i]; +} + +void MPU9250::readMagData() +{ + float destination[3] = {0,0,0}; + 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]) ; + } + } + + for(int i=0; i<=2; i++) + magCount[i] = (float)destination[i]; +} + +void MPU9250::readTempData() +{ + int16_t destination; + 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 + destination = (int16_t)(((int16_t)rawData[0]) << 8 | rawData[1]) ; // Turn the MSB and LSB into a 16-bit value + destination = ((float) destination) / 333.87f + 21.0f; + temperature = destination; +} + + +void MPU9250::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 MPU9250::initAK8963() +{ + float destination[3] = {0,0,0}; + // 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); + + for(int i=0; i<=2; i++) + magCalibration[i] = destination[i]; +} + + +void MPU9250::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 +} + +// 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() +{ + 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]); + */ + gyroBias[0] = (float) gyro_bias[0]/(float) gyrosensitivity; // construct gyro bias in deg/s for later manual subtraction + gyroBias[1] = (float) gyro_bias[1]/(float) gyrosensitivity; + gyroBias[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 + accelBias[0] = (float)accel_bias[0]/(float)accelsensitivity; + accelBias[1] = (float)accel_bias[1]/(float)accelsensitivity; + accelBias[2] = (float)accel_bias[2]/(float)accelsensitivity; +} + + +// Accelerometer and gyroscope self test; check calibration wrt factory settings +void MPU9250::MPU9250SelfTest() // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass +{ + //float destination[6] = {0,0,0,0,0,0}; + 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(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); + //delay(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( (float)1.01 , ((float)selfTest[0] - (float)1.0) )); // FT[Xa] factory trim calculation + factoryTrim[1] = (float)(2620/1<<FS)*(pow( (float)1.01 , ((float)selfTest[1] - (float)1.0) )); // FT[Ya] factory trim calculation + factoryTrim[2] = (float)(2620/1<<FS)*(pow( (float)1.01 , ((float)selfTest[2] - (float)1.0) )); // FT[Za] factory trim calculation + factoryTrim[3] = (float)(2620/1<<FS)*(pow( (float)1.01 , ((float)selfTest[3] - (float)1.0) )); // FT[Xg] factory trim calculation + factoryTrim[4] = (float)(2620/1<<FS)*(pow( (float)1.01 , ((float)selfTest[4] - (float)1.0) )); // FT[Yg] factory trim calculation + factoryTrim[5] = (float)(2620/1<<FS)*(pow( (float)1.01 , ((float)selfTest[5] - (float)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++) { + SelfTest[i] = (float)100.0*((float)(aSTAvg[i] - aAvg[i]))/factoryTrim[i]; // Report percent differences + SelfTest[i+3] = (float)100.0*((float)(gSTAvg[i] - gAvg[i]))/factoryTrim[i+3]; // Report percent differences + } + +} \ No newline at end of file