File content as of revision 2:855c83d4c7d6:

#include "MPU9250.h"

MPU9250 mpu9250;

Timer t;

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

    t.start();

    // Read the WHO_AM_I register, this is a good test of communication
    uint8_t whoami = mpu9250.readByte(MPU9250_ADDRESS, WHO_AM_I_MPU9250);  // Read WHO_AM_I register for MPU-9250
    

    if (whoami == 0x71) { // WHO_AM_I should always be 0x68
        wait(1);
        mpu9250.resetMPU9250(); // Reset registers to default in preparation for device calibration
        mpu9250.calibrateMPU9250(gyroBias, accelBias); // Calibrate gyro and accelerometers, load biases in bias registers
        wait(2);
        mpu9250.initMPU9250();
        mpu9250.initAK8963(magCalibration);
        wait(2);
    } else while(1) ; // Loop forever if communication doesn't happen

    mpu9250.getAres(); // Get accelerometer sensitivity
    mpu9250.getGres(); // Get gyro sensitivity
    mpu9250.getMres(); // Get magnetometer sensitivity

    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
}

int attitude_get(void)
{
    // If intPin goes high, all data registers have new data
    if(mpu9250.readByte(MPU9250_ADDRESS, INT_STATUS) & 0x01) {  // On interrupt, check if data ready interrupt

        mpu9250.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];

        mpu9250.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];

        mpu9250.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];


        Now = t.read_us();
        deltat = (float)((Now - lastUpdate)/1000000.0f) ; // set integration time by time elapsed since last filter update
        lastUpdate = Now;

        // Pass gyro rate as rad/s
        mpu9250.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);

        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   -= 13.8f; // Declination at Danville, California is 13 degrees 48 minutes and 47 seconds on 2014-04-04
        roll  *= 180.0f / PI;

        return 0;
    }
    return -1;
}