interface imu mpu9250
MPU9250.cpp
- Committer:
- soulx
- Date:
- 2016-01-20
- Revision:
- 0:b502ea2d6ebb
File content as of revision 0:b502ea2d6ebb:
#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 } }