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Diff: source/MPU9250.cpp
- Revision:
- 2:1957a4985d6e
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/source/MPU9250.cpp Sun Oct 28 13:45:26 2018 +0000
@@ -0,0 +1,460 @@
+#include "MPU9250.h"
+
+#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
+
+//******************************************************************************
+MPU9250::MPU9250(PinName sda, PinName scl)
+{
+ i2c_ = new I2C(sda, scl);
+ i2c_->frequency(400000);
+}
+
+//******************************************************************************
+MPU9250::MPU9250(I2C *i2c):i2c_(i2c){}
+
+//******************************************************************************
+MPU9250::~MPU9250()
+{
+ delete i2c_;
+}
+
+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::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::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::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::readAccelData(int16_t * destination)
+{
+ uint8_t rawData[6]; // x/y/z accel register data stored here
+ readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array
+ destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
+ destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
+ destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
+}
+
+void MPU9250::readGyroData(int16_t * destination)
+{
+ uint8_t rawData[6]; // x/y/z gyro register data stored here
+ readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array
+ destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
+ destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
+ destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
+}
+
+void MPU9250::readMagData(int16_t * destination)
+{
+ uint8_t rawData[7]; // x/y/z gyro register data, ST2 register stored here, must read ST2 at end of data acquisition
+ if(readByte(AK8963_ADDRESS, AK8963_ST1) & 0x01) { // wait for magnetometer data ready bit to be set
+ readBytes(AK8963_ADDRESS, AK8963_XOUT_L, 7, &rawData[0]); // Read the six raw data and ST2 registers sequentially into data array
+ uint8_t c = rawData[6]; // End data read by reading ST2 register
+ if(!(c & 0x08)) { // Check if magnetic sensor overflow set, if not then report data
+ destination[0] = (int16_t)(((int16_t)rawData[1] << 8) | rawData[0]); // Turn the MSB and LSB into a signed 16-bit value
+ destination[1] = (int16_t)(((int16_t)rawData[3] << 8) | rawData[2]) ; // Data stored as little Endian
+ destination[2] = (int16_t)(((int16_t)rawData[5] << 8) | rawData[4]) ;
+ }
+ }
+}
+
+int16_t MPU9250::readTempData()
+{
+ 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 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)
+{
+ // First extract the factory calibration for each magnetometer axis
+ uint8_t rawData[3]; // x/y/z gyro calibration data stored here
+ writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer
+ wait(0.01);
+ writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x0F); // Enter Fuse ROM access mode
+ wait(0.01);
+ readBytes(AK8963_ADDRESS, AK8963_ASAX, 3, &rawData[0]); // Read the x-, y-, and z-axis calibration values
+ destination[0] = (float)(rawData[0] - 128)/256.0f + 1.0f; // Return x-axis sensitivity adjustment values, etc.
+ destination[1] = (float)(rawData[1] - 128)/256.0f + 1.0f;
+ destination[2] = (float)(rawData[2] - 128)/256.0f + 1.0f;
+ writeByte(AK8963_ADDRESS, AK8963_CNTL, 0x00); // Power down magnetometer
+ wait(0.01);
+ // Configure the magnetometer for continuous read and highest resolution
+ // set Mscale bit 4 to 1 (0) to enable 16 (14) bit resolution in CNTL register,
+ // and enable continuous mode data acquisition Mmode (bits [3:0]), 0010 for 8 Hz and 0110 for 100 Hz sample rates
+ writeByte(AK8963_ADDRESS, AK8963_CNTL, Mscale << 4 | Mmode); // Set magnetometer data resolution and sample ODR
+ wait(0.01);
+}
+
+
+void MPU9250::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(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 MPU9250::MPU9250SelfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass
+{
+ uint8_t rawData[6] = {0, 0, 0, 0, 0, 0};
+ uint8_t selfTest[6];
+ int16_t gAvg[3], aAvg[3], aSTAvg[3], gSTAvg[3];
+ float factoryTrim[6];
+ uint8_t FS = 0;
+
+ writeByte(MPU9250_ADDRESS, SMPLRT_DIV, 0x00); // Set gyro sample rate to 1 kHz
+ writeByte(MPU9250_ADDRESS, CONFIG, 0x02); // Set gyro sample rate to 1 kHz and DLPF to 92 Hz
+ writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 1<<FS); // Set full scale range for the gyro to 250 dps
+ writeByte(MPU9250_ADDRESS, ACCEL_CONFIG2, 0x02); // Set accelerometer rate to 1 kHz and bandwidth to 92 Hz
+ writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 1<<FS); // Set full scale range for the accelerometer to 2 g
+
+ for( int ii = 0; ii < 200; ii++) { // get average current values of gyro and acclerometer
+
+ readBytes(MPU9250_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // Read the six raw data registers into data array
+ aAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
+ aAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
+ aAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
+
+ readBytes(MPU9250_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // Read the six raw data registers sequentially into data array
+ gAvg[0] += (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ; // Turn the MSB and LSB into a signed 16-bit value
+ gAvg[1] += (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;
+ gAvg[2] += (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ;
+ }
+
+ for (int ii =0; ii < 3; ii++) { // Get average of 200 values and store as average current readings
+ aAvg[ii] /= 200;
+ gAvg[ii] /= 200;
+ }
+
+// Configure the accelerometer for self-test
+ writeByte(MPU9250_ADDRESS, ACCEL_CONFIG, 0xE0); // Enable self test on all three axes and set accelerometer range to +/- 2 g
+ writeByte(MPU9250_ADDRESS, GYRO_CONFIG, 0xE0); // Enable self test on all three axes and set gyro range to +/- 250 degrees/s
+ 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
+ }
+
+}
\ No newline at end of file