Kris Winer
Basic program to obtain properly-scaled gyro, accelerometer, and magnetometer data from the MPU-9150 9-axis motion sensor. Nine-axis sensor fusion with Sebastian Madgwick's and Mahony's open-source sensor fusion filters running on an STM32F401RE Nucleo board at 84 MHz achieve sensor fusion filter update rates of ~5000 Hz. Additional info at https://github.com/kriswiner/STM32F401.
Dependencies: ST_401_84MHZ mbed
Diff: MPU9150.h
- Revision:
- 0:39935bb3c1a1
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/MPU9150.h Sun Jun 29 22:48:08 2014 +0000
@@ -0,0 +1,786 @@
+#ifndef MPU9150_H
+#define MPU9150_H
+
+#include "mbed.h"
+
+// Define registers per MPU6050, Register Map and Descriptions, Rev 4.2, 08/19/2013 6 DOF Motion sensor fusion device
+// Invensense Inc., www.invensense.com
+// See also MPU-9150 Register Map and Descriptions, Revision 4.0, RM-MPU-9150A-00, 9/12/2012 for registers not listed in
+// above document; the MPU6050 and MPU 9150 are virtually identical but the latter has an on-board magnetic sensor
+//
+//Magnetometer Registers
+#define WHO_AM_I_AK8975A 0x00 // should return 0x48
+#define INFO 0x01
+#define AK8975A_ST1 0x02 // data ready status bit 0
+#define AK8975A_ADDRESS 0x0C<<1
+#define AK8975A_XOUT_L 0x03 // data
+#define AK8975A_XOUT_H 0x04
+#define AK8975A_YOUT_L 0x05
+#define AK8975A_YOUT_H 0x06
+#define AK8975A_ZOUT_L 0x07
+#define AK8975A_ZOUT_H 0x08
+#define AK8975A_ST2 0x09 // Data overflow bit 3 and data read error status bit 2
+#define AK8975A_CNTL 0x0A // Power down (0000), single-measurement (0001), self-test (1000) and Fuse ROM (1111) modes on bits 3:0
+#define AK8975A_ASTC 0x0C // Self test control
+#define AK8975A_ASAX 0x10 // Fuse ROM x-axis sensitivity adjustment value
+#define AK8975A_ASAY 0x11 // Fuse ROM y-axis sensitivity adjustment value
+#define AK8975A_ASAZ 0x12 // Fuse ROM z-axis sensitivity adjustment value
+
+#define XGOFFS_TC 0x00 // Bit 7 PWR_MODE, bits 6:1 XG_OFFS_TC, bit 0 OTP_BNK_VLD
+#define YGOFFS_TC 0x01
+#define ZGOFFS_TC 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 0x0D
+#define SELF_TEST_Y 0x0E
+#define SELF_TEST_Z 0x0F
+#define SELF_TEST_A 0x10
+#define XG_OFFS_USRH 0x13 // User-defined trim values for gyroscope, populate with calibration routine
+#define XG_OFFS_USRL 0x14
+#define YG_OFFS_USRH 0x15
+#define YG_OFFS_USRL 0x16
+#define ZG_OFFS_USRH 0x17
+#define ZG_OFFS_USRL 0x18
+#define SMPLRT_DIV 0x19
+#define CONFIG 0x1A
+#define GYRO_CONFIG 0x1B
+#define ACCEL_CONFIG 0x1C
+#define FF_THR 0x1D // Free-fall
+#define FF_DUR 0x1E // Free-fall
+#define MOT_THR 0x1F // Motion detection threshold bits [7:0]
+#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_MPU9150 0x75 // Should return 0x68
+
+
+// Using the GY-9150 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 MPU9150_ADDRESS 0x69<<1 // Device address when ADO = 1
+#else
+#define MPU9150_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
+};
+
+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
+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
+
+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 magCalibration[3] = {0, 0, 0}, magbias[3] = {0, 0, 0}; // Factory mag calibration and mag bias
+float gyroBias[3] = {0, 0, 0}, accelBias[3] = {0, 0, 0}; // Bias corrections for gyro and accelerometer
+float ax, ay, az, gx, gy, gz, mx, my, mz; // variables to hold latest sensor data values
+int16_t tempCount; // Stores the real internal chip temperature in degrees Celsius
+float temperature;
+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
+
+float pitch, yaw, roll;
+float deltat = 0.0f; // integration interval for both filter schemes
+int lastUpdate = 0, firstUpdate = 0, Now = 0; // used to calculate integration interval // used to calculate integration interval
+float q[4] = {1.0f, 0.0f, 0.0f, 0.0f}; // vector to hold quaternion
+float eInt[3] = {0.0f, 0.0f, 0.0f}; // vector to hold integral error for Mahony method
+
+class MPU9150 {
+
+ protected:
+
+ public:
+ //===================================================================================================================
+//====== 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);
+}
+
+ 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 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(int16_t * destination)
+{
+ uint8_t rawData[6]; // x/y/z accel register data stored here
+ readBytes(MPU9150_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 readGyroData(int16_t * destination)
+{
+ uint8_t rawData[6]; // x/y/z gyro register data stored here
+ readBytes(MPU9150_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 readMagData(int16_t * destination)
+{
+ uint8_t rawData[6]; // x/y/z gyro register data stored here
+ writeByte(AK8975A_ADDRESS, AK8975A_CNTL, 0x01); // toggle enable data read from magnetometer, no continuous read mode!
+ wait(0.01);
+ // Only accept a new magnetometer data read if the data ready bit is set and
+ // if there are no sensor overflow or data read errors
+ if(readByte(AK8975A_ADDRESS, AK8975A_ST1) & 0x01) { // wait for magnetometer data ready bit to be set
+ readBytes(AK8975A_ADDRESS, AK8975A_XOUT_L, 6, &rawData[0]); // Read the six raw data registers sequentially into data array
+ destination[0] = ((int16_t)rawData[1] << 8) | rawData[0] ; // Turn the MSB and LSB into a signed 16-bit value
+ destination[1] = ((int16_t)rawData[3] << 8) | rawData[2] ;
+ destination[2] = ((int16_t)rawData[5] << 8) | rawData[4] ;
+ }
+}
+
+void initAK8975A(float * destination)
+{
+ uint8_t rawData[3]; // x/y/z gyro register data stored here
+ writeByte(AK8975A_ADDRESS, AK8975A_CNTL, 0x00); // Power down
+ wait(0.01);
+ writeByte(AK8975A_ADDRESS, AK8975A_CNTL, 0x0F); // Enter Fuse ROM access mode
+ wait(0.01);
+ readBytes(AK8975A_ADDRESS, AK8975A_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
+ destination[1] = (float)(rawData[1] - 128)/256.0f + 1.0f;
+ destination[2] = (float)(rawData[2] - 128)/256.0f + 1.0f;
+}
+
+int16_t readTempData()
+{
+ uint8_t rawData[2]; // x/y/z gyro register data stored here
+ readBytes(MPU9150_ADDRESS, TEMP_OUT_H, 2, &rawData[0]); // Read the two raw data registers sequentially into data array
+ return ((int16_t)rawData[0] << 8) | rawData[1] ; // Turn the MSB and LSB into a 16-bit value
+}
+
+void resetMPU9150() {
+ // reset device
+ writeByte(MPU9150_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
+ wait(0.1);
+ }
+
+
+
+void initMPU9150()
+{
+ // Initialize MPU9150 device
+ // wake up device
+ writeByte(MPU9150_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(MPU9150_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(MPU9150_ADDRESS, CONFIG, 0x03);
+
+ // Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV)
+ writeByte(MPU9150_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(MPU9150_ADDRESS, GYRO_CONFIG);
+ writeByte(MPU9150_ADDRESS, GYRO_CONFIG, c & ~0xE0); // Clear self-test bits [7:5]
+ writeByte(MPU9150_ADDRESS, GYRO_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
+ writeByte(MPU9150_ADDRESS, GYRO_CONFIG, c | Gscale << 3); // Set full scale range for the gyro
+
+ // Set accelerometer configuration
+ c = readByte(MPU9150_ADDRESS, ACCEL_CONFIG);
+ writeByte(MPU9150_ADDRESS, ACCEL_CONFIG, c & ~0xE0); // Clear self-test bits [7:5]
+ writeByte(MPU9150_ADDRESS, ACCEL_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
+ writeByte(MPU9150_ADDRESS, ACCEL_CONFIG, c | Ascale << 3); // Set full scale range for the accelerometer
+
+ // 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(MPU9150_ADDRESS, INT_PIN_CFG, 0x22);
+ writeByte(MPU9150_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 calibrateMPU9150(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(MPU9150_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(MPU9150_ADDRESS, PWR_MGMT_1, 0x01);
+ writeByte(MPU9150_ADDRESS, PWR_MGMT_2, 0x00);
+ wait(0.2);
+
+// Configure device for bias calculation
+ writeByte(MPU9150_ADDRESS, INT_ENABLE, 0x00); // Disable all interrupts
+ writeByte(MPU9150_ADDRESS, FIFO_EN, 0x00); // Disable FIFO
+ writeByte(MPU9150_ADDRESS, PWR_MGMT_1, 0x00); // Turn on internal clock source
+ writeByte(MPU9150_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master
+ writeByte(MPU9150_ADDRESS, USER_CTRL, 0x00); // Disable FIFO and I2C master modes
+ writeByte(MPU9150_ADDRESS, USER_CTRL, 0x0C); // Reset FIFO and DMP
+ wait(0.015);
+
+// Configure MPU9150 gyro and accelerometer for bias calculation
+ writeByte(MPU9150_ADDRESS, CONFIG, 0x01); // Set low-pass filter to 188 Hz
+ writeByte(MPU9150_ADDRESS, SMPLRT_DIV, 0x00); // Set sample rate to 1 kHz
+ writeByte(MPU9150_ADDRESS, GYRO_CONFIG, 0x00); // Set gyro full-scale to 250 degrees per second, maximum sensitivity
+ writeByte(MPU9150_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(MPU9150_ADDRESS, USER_CTRL, 0x40); // Enable FIFO
+ writeByte(MPU9150_ADDRESS, FIFO_EN, 0x78); // Enable gyro and accelerometer sensors for FIFO (max size 1024 bytes in MPU9150)
+ wait(0.08); // accumulate 80 samples in 80 milliseconds = 960 bytes
+
+// At end of sample accumulation, turn off FIFO sensor read
+ writeByte(MPU9150_ADDRESS, FIFO_EN, 0x00); // Disable gyro and accelerometer sensors for FIFO
+ readBytes(MPU9150_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(MPU9150_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(MPU9150_ADDRESS, XG_OFFS_USRH, data[0]);
+ writeByte(MPU9150_ADDRESS, XG_OFFS_USRL, data[1]);
+ writeByte(MPU9150_ADDRESS, YG_OFFS_USRH, data[2]);
+ writeByte(MPU9150_ADDRESS, YG_OFFS_USRL, data[3]);
+ writeByte(MPU9150_ADDRESS, ZG_OFFS_USRH, data[4]);
+ writeByte(MPU9150_ADDRESS, ZG_OFFS_USRL, 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(MPU9150_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(MPU9150_ADDRESS, YA_OFFSET_H, 2, &data[0]);
+ accel_bias_reg[1] = (int16_t) ((int16_t)data[0] << 8) | data[1];
+ readBytes(MPU9150_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(MPU9150_ADDRESS, XA_OFFSET_H, data[0]);
+ writeByte(MPU9150_ADDRESS, XA_OFFSET_L_TC, data[1]);
+ writeByte(MPU9150_ADDRESS, YA_OFFSET_H, data[2]);
+ writeByte(MPU9150_ADDRESS, YA_OFFSET_L_TC, data[3]);
+ writeByte(MPU9150_ADDRESS, ZA_OFFSET_H, data[4]);
+ writeByte(MPU9150_ADDRESS, ZA_OFFSET_L_TC, 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 MPU9150SelfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass
+{
+ uint8_t rawData[4] = {0, 0, 0, 0};
+ uint8_t selfTest[6];
+ float factoryTrim[6];
+
+ // Configure the accelerometer for self-test
+ writeByte(MPU9150_ADDRESS, ACCEL_CONFIG, 0xF0); // Enable self test on all three axes and set accelerometer range to +/- 8 g
+ writeByte(MPU9150_ADDRESS, GYRO_CONFIG, 0xE0); // Enable self test on all three axes and set gyro range to +/- 250 degrees/s
+ wait(0.25); // Delay a while to let the device execute the self-test
+ rawData[0] = readByte(MPU9150_ADDRESS, SELF_TEST_X); // X-axis self-test results
+ rawData[1] = readByte(MPU9150_ADDRESS, SELF_TEST_Y); // Y-axis self-test results
+ rawData[2] = readByte(MPU9150_ADDRESS, SELF_TEST_Z); // Z-axis self-test results
+ rawData[3] = readByte(MPU9150_ADDRESS, SELF_TEST_A); // Mixed-axis self-test results
+ // Extract the acceleration test results first
+ selfTest[0] = (rawData[0] >> 3) | (rawData[3] & 0x30) >> 4 ; // XA_TEST result is a five-bit unsigned integer
+ selfTest[1] = (rawData[1] >> 3) | (rawData[3] & 0x0C) >> 4 ; // YA_TEST result is a five-bit unsigned integer
+ selfTest[2] = (rawData[2] >> 3) | (rawData[3] & 0x03) >> 4 ; // ZA_TEST result is a five-bit unsigned integer
+ // Extract the gyration test results first
+ selfTest[3] = rawData[0] & 0x1F ; // XG_TEST result is a five-bit unsigned integer
+ selfTest[4] = rawData[1] & 0x1F ; // YG_TEST result is a five-bit unsigned integer
+ selfTest[5] = rawData[2] & 0x1F ; // ZG_TEST result is a five-bit unsigned integer
+ // Process results to allow final comparison with factory set values
+ factoryTrim[0] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[0] - 1.0f)/30.0f))); // FT[Xa] factory trim calculation
+ factoryTrim[1] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[1] - 1.0f)/30.0f))); // FT[Ya] factory trim calculation
+ factoryTrim[2] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[2] - 1.0f)/30.0f))); // FT[Za] factory trim calculation
+ factoryTrim[3] = ( 25.0f*131.0f)*(pow( 1.046f , (selfTest[3] - 1.0f) )); // FT[Xg] factory trim calculation
+ factoryTrim[4] = (-25.0f*131.0f)*(pow( 1.046f , (selfTest[4] - 1.0f) )); // FT[Yg] factory trim calculation
+ factoryTrim[5] = ( 25.0f*131.0f)*(pow( 1.046f , (selfTest[5] - 1.0f) )); // FT[Zg] factory trim calculation
+
+ // Output self-test results and factory trim calculation if desired
+ // Serial.println(selfTest[0]); Serial.println(selfTest[1]); Serial.println(selfTest[2]);
+ // Serial.println(selfTest[3]); Serial.println(selfTest[4]); Serial.println(selfTest[5]);
+ // Serial.println(factoryTrim[0]); Serial.println(factoryTrim[1]); Serial.println(factoryTrim[2]);
+ // Serial.println(factoryTrim[3]); Serial.println(factoryTrim[4]); Serial.println(factoryTrim[5]);
+
+ // Report results as a ratio of (STR - FT)/FT; the change from Factory Trim of the Self-Test Response
+ // To get to percent, must multiply by 100 and subtract result from 100
+ for (int i = 0; i < 6; i++) {
+ destination[i] = 100.0f + 100.0f*(selfTest[i] - factoryTrim[i])/factoryTrim[i]; // 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
MPU-9150