File content as of revision 2:c7897a3f5f11:

#include "MPU9250.h"


uint8_t Ascale = AFS_2G;     // AFS_2G, AFS_4G, AFS_8G, AFS_16G
uint8_t Gscale = GFS_250DPS; // GFS_250DPS, GFS_500DPS, GFS_1000DPS, GFS_2000DPS
uint8_t Mscale = MFS_16BITS; // MFS_14BITS or MFS_16BITS, 14-bit or 16-bit magnetometer resolution
uint8_t Mmode = 0x06;        // Either 8 Hz 0x02) or 100 Hz (0x06) magnetometer data ODR
float aRes, gRes, mRes;      // scale resolutions per LSB for the sensors

//Set up I2C, (SDA,SCL)
I2C i2c(PB_9, PB_8);

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 vx, vy, vz;
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 v_trans[3] = {0.0f, 0.0f, 0.0f};                 // vector to hold translative velocities
float a_old[3] = {0.00f, 0.00f, 0.00f};
float eInt[3] = {0.0f, 0.0f, 0.0f};              // vector to hold integral error for Mahony method

accData_t myData;
Timer t;

#define SAMPLE_TIME 100

#define STEP_NUMBER 5
float sum = 0;
uint32_t sumCount = 0;
char buffer[14];
float ax_sum = 0;
static float vx_buffer[STEP_NUMBER];
static int8_t stepCounter = 0;


// MPU9250-Constructor
MPU9250::MPU9250(Serial* serialPtr)
{
    pc = serialPtr;
    imuSetup();
    vx_old = 0;
}



//===================================================================================================================
//====== Set of useful function to access acceleratio, gyroscope, and temperature data
//===================================================================================================================

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(0.025); // 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(0.025); // Delay a while to let the device stabilize

    // Retrieve accelerometer and gyro factory Self-Test Code from USR_Reg
    selfTest[0] = readByte(MPU9250_ADDRESS, SELF_TEST_X_ACCEL); // X-axis accel self-test results
    selfTest[1] = readByte(MPU9250_ADDRESS, SELF_TEST_Y_ACCEL); // Y-axis accel self-test results
    selfTest[2] = readByte(MPU9250_ADDRESS, SELF_TEST_Z_ACCEL); // Z-axis accel self-test results
    selfTest[3] = readByte(MPU9250_ADDRESS, SELF_TEST_X_GYRO); // X-axis gyro self-test results
    selfTest[4] = readByte(MPU9250_ADDRESS, SELF_TEST_Y_GYRO); // Y-axis gyro self-test results
    selfTest[5] = readByte(MPU9250_ADDRESS, SELF_TEST_Z_GYRO); // Z-axis gyro self-test results

    // Retrieve factory self-test value from self-test code reads
    factoryTrim[0] = (float)(2620/1<<FS)*(pow( 1.01, ((float)selfTest[0] - 1.0) ));  // FT[Xa] factory trim calculation
    factoryTrim[1] = (float)(2620/1<<FS)*(pow( 1.01, ((float)selfTest[1] - 1.0) ));  // FT[Ya] factory trim calculation
    factoryTrim[2] = (float)(2620/1<<FS)*(pow( 1.01, ((float)selfTest[2] - 1.0) ));  // FT[Za] factory trim calculation
    factoryTrim[3] = (float)(2620/1<<FS)*(pow( 1.01, ((float)selfTest[3] - 1.0) ));  // FT[Xg] factory trim calculation
    factoryTrim[4] = (float)(2620/1<<FS)*(pow( 1.01, ((float)selfTest[4] - 1.0) ));  // FT[Yg] factory trim calculation
    factoryTrim[5] = (float)(2620/1<<FS)*(pow( 1.01, ((float)selfTest[5] - 1.0) ));  // FT[Zg] factory trim calculation

// Report results as a ratio of (STR - FT)/FT; the change from Factory Trim of the Self-Test Response
// To get percent, must multiply by 100
    for (int i = 0; i < 3; i++) {
        destination[i] = 100.0*((float)(aSTAvg[i] - aAvg[i]))/factoryTrim[i]; // Report percent differences
        destination[i+3] = 100.0*((float)(gSTAvg[i] - gAvg[i]))/factoryTrim[i+3]; // Report percent differences
    }

}



// Implementation of Sebastian Madgwick's "...efficient orientation filter for... inertial/magnetic sensor arrays"
// (see http://www.x-io.co.uk/category/open-source/ for examples and more details)
// which fuses acceleration, rotation rate, and magnetic moments to produce a quaternion-based estimate of absolute
// device orientation -- which can be converted to yaw, pitch, and roll. Useful for stabilizing quadcopters, etc.
// The performance of the orientation filter is at least as good as conventional Kalman-based filtering algorithms
// but is much less computationally intensive---it can be performed on a 3.3 V Pro Mini operating at 8 MHz!
void MPU9250::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;

}


void MPU9250::readIMU()
{
    // 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(accelCount);  // Read the x/y/z adc values
        // 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(gyroCount);  // Read the x/y/z adc values
        // 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(magCount);  // Read the x/y/z adc values
        // Calculate the magnetometer values in milliGauss
        // Include factory calibration per data sheet and user environmental corrections
        mx = (float)magCount[0]*mRes*magCalibration[0] - magbias[0];  // get actual magnetometer value, this depends on scale being set
        my = (float)magCount[1]*mRes*magCalibration[1] - magbias[1];
        mz = (float)magCount[2]*mRes*magCalibration[2] - magbias[2];
    }
    


    //pc.printf("ax, ay, az, delta_t;%f;%f;%f;%f\n\r", ax, ay, az*GRAVITATION + GRAVITATION, deltat);

    Now = t.read_us();

    deltat = (float)((Now - lastUpdate)/1000000.0f) ; // set integration time by time elapsed since last filter update
    lastUpdate = Now;
    
    //pc.printf("%f,%f,%f,%f\n\r",ax, ay, az, deltat);


    sum += deltat;
    sumCount++;

    // Pass gyro rate as rad/s
    MadgwickQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f,  my,  mx, mz);
    //mpu9250.MahonyQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f, my, mx, mz);

    // Serial print and/or display at 0.5 s rate independent of data rates
    delt_t = t.read_ms() - _count;
    //pc.printf("Zeit intern: %d\n\r", t.read_ms());
}



/*//-----------------------------------------
// Update displayed value
if (delt_t > SAMPLE_TIME) {



    //pc.printf("vx, vy, vz: %f %f %f\n\r", v_trans[0], v_trans[1], v_trans[2]);


    yaw   = atan2(2.0f * (q[1] * q[2] + q[0] * q[3]), q[0] * q[0] + q[1] * q[1] - q[2] * q[2] - q[3] * q[3]);
    pitch = -asin(2.0f * (q[1] * q[3] - q[0] * q[2]));
    roll  = atan2(2.0f * (q[0] * q[1] + q[2] * q[3]), q[0] * q[0] - q[1] * q[1] - q[2] * q[2] + q[3] * q[3]);
    pitch *= 180.0f / PI;
    yaw   *= 180.0f / PI;
    yaw   -= 2.93f; // Declination at 8572 Berg TG: +2° 56'
    roll  *= 180.0f / PI;



    myled= !myled;
    _count = t.read_ms();

    if(_count > 1<<21) {
        t.start(); // start the timer over again if ~30 minutes has passed
        _count = 0;
        deltat= 0;
        lastUpdate = t.read_us();
    }
    sum = 0;
    sumCount = 0;
}*/



void MPU9250::imuSetup()
{
    //Set up I2C
    i2c.frequency(400000);  // use fast (400 kHz) I2C

    pc->printf("CPU SystemCoreClock is %d Hz\r\n", SystemCoreClock);

    t.start();
//  lcd.setBrightness(0.05);


    // Read the WHO_AM_I register, this is a good test of communication
    uint8_t 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");
        sprintf(buffer, "0x%x", whoami);
        wait(1);

        resetMPU9250(); // Reset registers to default in preparation for device calibration
        MPU9250SelfTest(SelfTest); // 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(gyroBias, accelBias); // 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(magCalibration);
        pc->printf("AK8963 initialized for active data mode....\n\r"); // Initialize device for active mode read of magnetometer
        pc->printf("Accelerometer full-scale range = %f  g\n\r", 2.0f*(float)(1<<Ascale));
        pc->printf("Gyroscope full-scale range = %f  deg/s\n\r", 250.0f*(float)(1<<Gscale));
        if(Mscale == 0) pc->printf("Magnetometer resolution = 14  bits\n\r");
        if(Mscale == 1) pc->printf("Magnetometer resolution = 16  bits\n\r");
        if(Mmode == 2) pc->printf("Magnetometer ODR = 8 Hz\n\r");
        if(Mmode == 6) pc->printf("Magnetometer ODR = 100 Hz\n\r");
        wait(1);
    } else {
        pc->printf("Could not connect to MPU9250: \n\r");
        pc->printf("%#x \n",  whoami);
        sprintf(buffer, "WHO_AM_I 0x%x", whoami);

        while(1) {
            // Loop forever if communication doesn't happen
            pc->printf("no IMU detected (verify if it's plugged in)\n\r");
        }
    }

    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);
    magbias[0] = +470.;  // User environmental x-axis correction in milliGauss, should be automatically calculated
    magbias[1] = +120.;  // User environmental x-axis correction in milliGauss
    magbias[2] = +125.;  // User environmental x-axis correction in milliGauss
}


// N Werte sammeln, Integrale aufsummieren
/*float MPU9250::getMedianAcc(){
    int8_t i;
    ax_sum = 0;
    for (i=0; i<STEP_NUMBER; i++) {
        readIMU();
        //pc.printf("Zeit extern: %d\n\n\r", t.read_ms());
        pc.printf("i=%d: ax=%f\n\r", i, ax);
        ax_sum += ax;
    }
    pc.printf("Summe: %f\n\n\r", ax_sum/steps);
    return ax_sum/steps;
}*/


// BufferArray-Variante
float MPU9250::getVBuffer()
{
    // Save the last ax value before readIMU() is executed
    float ax_old = ax;
    
    // Save the last vx value
    if (stepCounter == 0) {
        vx_old = vx_buffer[STEP_NUMBER-1];
    }
    else{
        vx_old = vx_buffer[stepCounter - 1];
    }
    
    
    // Sets new ax value
    readIMU();


    // Calculate Integration Step of new and old value
    vx_buffer[stepCounter] = vx_old + deltat*0.5f*(ax + ax_old)/GRAVITATION;

    int i;
    float vx_median = 0;
    for (i=0; i<STEP_NUMBER; i++) {
        vx_median += vx_buffer[i];
        //pc.printf("%d: %f\n\r", i, vx_buffer[i]);
    }
    //pc.printf("\n\r");
    //pc.printf("%f,%f,%f,%f\n\r", ax, vx_median/STEP_NUMBER, vx_buffer[stepCounter], deltat);

    stepCounter++;
    if (stepCounter >= STEP_NUMBER) {
        stepCounter = 0;
    }
    return vx_median/STEP_NUMBER;
}