File content as of revision 2:c1c7afb86416:

#include "mbed.h"
#include "MPU9250.h"
#include "BMP280.h"

#define bmpadr 0x76<<1 // SD0 pulldown 0x76<<1  , pullup 0x77<<1

//I2C SDA,SCL:  PC_9, PA_8

SPI spi(PC_12, PC_11, PC_10); // mosi, miso, sclk
DigitalOut cs(PA_15);
Serial pc(PA_2,PA_3);  //v2
//Serial pc(PA_9,PA_10);   //original

float sum = 0;
uint32_t sumCount = 0;
float bmpTEM , bmpPRE;
MPU9250 mpu9250;
BMP280 bmp(PC_9, PA_8 ,bmpadr);    //(PinName sda, PinName scl, char slave_adr)
Timer t;
float PRES_first;

int main() {
    wait(2);
    pc.baud(9600);
    //a8=0;
    //c9=0;
    pc.printf("SkipperS2 Peripheral Test...\n");wait(1);
        pc.printf("L2G2IS SPI 0xD9?\n");
        // Chip must be deselected
        cs = 1;
        // Setup the spi for 8 bit data, high steady state clock,
        // second edge capture, with a 1MHz clock rate
        spi.format(8,3);
        spi.frequency(1000000);
        // Select the device by seting chip select low
        cs = 0;
        // Send 0x8f, the command to read the WHOAMI register
        spi.write(0x80);
        // Send a dummy byte to receive the contents of the WHOAMI register
        int whoami_l2 = spi.write(0x00);
        pc.printf("WHOAMI register = 0x%X\n", whoami_l2);
        // Deselect the device
        cs = 1;
        
        pc.printf("MPU9250 I2C test\n");
    
    
    
    
  //Set up I2C
  i2c.frequency(400000);  // use fast (400 kHz) I2C  
  
  pc.printf("CPU SystemCoreClock is %d Hz\r\n", SystemCoreClock);   
  
  t.start();        
  
  //BMP initialize
  bmp.initialize();
  PRES_first = bmp.getPressure();
    
  // 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
  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 is online...\n\r");
    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  
    //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);
    mpu9250.initMPU9250(); 
    pc.printf("MPU9250 initialized for active data mode....\n\r"); // Initialize device for active mode read of acclerometer, gyroscope, and temperature
    mpu9250.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(2);
   }
   else
   {
    pc.printf("Could not connect to MPU9250: \n\r");
    pc.printf("%#x \n",  whoami);
    
    
    while(1) ; // Loop forever if communication doesn't happen
    }

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

 while(1) {
  
  // 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;
    
    sum += deltat;
    sumCount++;
    
//    if(lastUpdate - firstUpdate > 10000000.0f) {
//     beta = 0.04;  // decrease filter gain after stabilized
//     zeta = 0.015; // increasey bias drift gain after stabilized
 //   }
    
   // 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);

    // Serial print and/or display at 0.5 s rate independent of data rates
    delt_t = t.read_ms() - count;
    if (delt_t > 500) { // update LCD once per half-second independent of read rate

    //pc.printf("ax = %f", 1000*ax); 
    //pc.printf(" ay = %f", 1000*ay); 
    //pc.printf(" az = %f  mg\n\r", 1000*az); 

    //pc.printf("gx = %f", gx); 
    //pc.printf(" gy = %f", gy); 
    //pc.printf(" gz = %f  deg/s\n\r", gz); 
    
    //pc.printf("gx = %f", mx); 
    //pc.printf(" gy = %f", my); 
    //pc.printf(" gz = %f  mG\n\r", mz); 
    
    tempCount = mpu9250.readTempData();  // Read the adc values
    temperature = ((float) tempCount) / 333.87f + 21.0f; // Temperature in degrees Centigrade
    //pc.printf(" temperature = %f  C\n\r", temperature); 
    
    //pc.printf("q0 = %f\n\r", q[0]);
    //pc.printf("q1 = %f\n\r", q[1]);
    //pc.printf("q2 = %f\n\r", q[2]);
    //pc.printf("q3 = %f\n\r", q[3]);      
    
      
  // Define output variables from updated quaternion---these are Tait-Bryan angles, commonly used in aircraft orientation.
  // In this coordinate system, the positive z-axis is down toward Earth. 
  // Yaw is the angle between Sensor x-axis and Earth magnetic North (or true North if corrected for local declination, looking down on the sensor positive yaw is counterclockwise.
  // Pitch is angle between sensor x-axis and Earth ground plane, toward the Earth is positive, up toward the sky is negative.
  // Roll is angle between sensor y-axis and Earth ground plane, y-axis up is positive roll.
  // These arise from the definition of the homogeneous rotation matrix constructed from quaternions.
  // Tait-Bryan angles as well as Euler angles are non-commutative; that is, the get the correct orientation the rotations must be
  // applied in the correct order which for this configuration is yaw, pitch, and then roll.
  // For more see http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles which has additional links.
    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;

    //pc.printf("Yaw,   Pitch,   Roll:  %f  %f  %f \n\r",  yaw,   pitch,   roll);
    //pc.printf("average rate = %f\n\r", (float) sumCount/sum);
    
    bmpTEM=bmp.getTemperature();
    bmpPRE=bmp.getPressure();    
    pc.printf("PRE : %f\n",bmpPRE - PRES_first);
 
    myled= !myled;
    count = t.read_ms(); 
    sum = 0;
    sumCount = 0; 
}
}
     
    while(1){
        pc.printf(".");
        wait(1);
    }
}