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

Files at this revision

API Documentation at this revision

Comitter:
onehorse
Date:
Sun Jun 29 22:48:08 2014 +0000
Commit message:
Basic program to get properly-scaled gyro, accelerometer, and magnetometer data from the MPU9150 9-axis motion sensor. Sensor fusion is performed using Madgwick and Mahony open-source MARG fusion filters.

Changed in this revision

MPU9150.h Show annotated file Show diff for this revision Revisions of this file
N5110.lib Show annotated file Show diff for this revision Revisions of this file
ST_401_84MHZ.lib Show annotated file Show diff for this revision Revisions of this file
main.cpp Show annotated file Show diff for this revision Revisions of this file
mbed.bld Show annotated file Show diff for this revision Revisions of this file
--- /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
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/N5110.lib	Sun Jun 29 22:48:08 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/onehorse/code/Adfs/#28c629d0b0d0
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/ST_401_84MHZ.lib	Sun Jun 29 22:48:08 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/dreschpe/code/ST_401_84MHZ/#b9343c8b85ec
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun Jun 29 22:48:08 2014 +0000
@@ -0,0 +1,253 @@
+/* MPU9150 Basic Example Code
+ by: Kris Winer
+ date: April 1, 2014
+ license: Beerware - Use this code however you'd like. If you 
+ find it useful you can buy me a beer some time.
+ 
+ Demonstrate basic MPU-9150 functionality including parameterizing the register addresses, initializing the sensor, 
+ getting properly scaled accelerometer, gyroscope, and magnetometer data out. Added display functions to 
+ allow display to on breadboard monitor. Addition of 9 DoF sensor fusion using open source Madgwick and 
+ Mahony filter algorithms. Sketch runs on the 3.3 V 8 MHz Pro Mini and the Teensy 3.1.
+ 
+ SDA and SCL should have external pull-up resistors (to 3.3V).
+ 10k resistors are on the EMSENSR-9250 breakout board.
+ 
+ Hardware setup:
+ MPU9150 Breakout --------- Arduino
+ VDD ---------------------- 3.3V
+ VDDI --------------------- 3.3V
+ SDA ----------------------- A4
+ SCL ----------------------- A5
+ GND ---------------------- GND
+ 
+ Note: The MPU9150 is an I2C sensor and uses the Arduino Wire library. 
+ Because the sensor is not 5V tolerant, we are using a 3.3 V 8 MHz Pro Mini or a 3.3 V Teensy 3.1.
+ We have disabled the internal pull-ups used by the Wire library in the Wire.h/twi.c utility file.
+ We are also using the 400 kHz fast I2C mode by setting the TWI_FREQ  to 400000L /twi.h utility file.
+ */
+ 
+//#include "ST_F401_84MHZ.h" 
+//F401_init84 myinit(0);
+#include "mbed.h"
+#include "MPU9150.h"
+#include "N5110.h"
+
+// Using NOKIA 5110 monochrome 84 x 48 pixel display
+// pin 9 - Serial clock out (SCLK)
+// pin 8 - Serial data out (DIN)
+// pin 7 - Data/Command select (D/C)
+// pin 5 - LCD chip select (CS)
+// pin 6 - LCD reset (RST)
+//Adafruit_PCD8544 display = Adafruit_PCD8544(9, 8, 7, 5, 6);
+
+float sum = 0;
+uint32_t sumCount = 0, mcount = 0;
+char buffer[14];
+
+   MPU9150 MPU9150;
+   
+   Timer t;
+
+   Serial pc(USBTX, USBRX); // tx, rx
+
+   //        VCC,   SCE,  RST,  D/C,  MOSI,S CLK, LED
+   N5110 lcd(PA_8, PB_10, PA_9, PA_6, PA_7, PA_5, PC_7);
+   
+
+        
+int main()
+{
+  pc.baud(9600);  
+
+  //Set up I2C
+  i2c.frequency(400000);  // use fast (400 kHz) I2C  
+  
+  pc.printf("CPU SystemCoreClock is %d Hz\r\n", SystemCoreClock);   
+  
+  t.start();        
+  
+  lcd.init();
+//  lcd.setBrightness(0.05);
+  
+    
+  // Read the WHO_AM_I register, this is a good test of communication
+  uint8_t whoami = MPU9150.readByte(MPU9150_ADDRESS, WHO_AM_I_MPU9150);  // Read WHO_AM_I register for MPU-9250
+  pc.printf("I AM 0x%x\n\r", whoami); pc.printf("I SHOULD BE 0x68\n\r");
+  
+  if (whoami == 0x68) // WHO_AM_I should be 0x68
+  {  
+    pc.printf("MPU9150 WHO_AM_I is 0x%x\n\r", whoami);
+    pc.printf("MPU9150 is online...\n\r");
+    lcd.clear();
+    lcd.printString("MPU9150 is", 0, 0);
+    sprintf(buffer, "0x%x", whoami);
+    lcd.printString(buffer, 0, 1);
+    lcd.printString("shoud be 0x68", 0, 2);  
+    wait(1);
+    
+    MPU9150.MPU9150SelfTest(SelfTest);
+    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]);
+    wait(1);
+    MPU9150.resetMPU9150(); // Reset registers to default in preparation for device calibration
+    MPU9150.calibrateMPU9150(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(1);
+    MPU9150.initMPU9150(); 
+    pc.printf("MPU9150 initialized for active data mode....\n\r"); // Initialize device for active mode read of acclerometer, gyroscope, and temperature
+    MPU9150.initAK8975A(magCalibration);
+    pc.printf("AK8975 initialized for active data mode....\n\r"); // Initialize device for active mode read of magnetometer
+   }
+   else
+   {
+    pc.printf("Could not connect to MPU9150: \n\r");
+    pc.printf("%#x \n",  whoami);
+ 
+    lcd.clear();
+    lcd.printString("MPU9150", 0, 0);
+    lcd.printString("no connection", 0, 1);
+    sprintf(buffer, "WHO_AM_I 0x%x", whoami);
+    lcd.printString(buffer, 0, 2); 
+ 
+    while(1) ; // Loop forever if communication doesn't happen
+    }
+
+    uint8_t MagRate = 10; // set magnetometer read rate in Hz; 10 to 100 (max) Hz are reasonable values
+    MPU9150.getAres(); // Get accelerometer sensitivity
+    MPU9150.getGres(); // Get gyro sensitivity
+    mRes = 10.*1229./4096.; // Conversion from 1229 microTesla full scale (4096) to 12.29 Gauss full scale
+    // So far, magnetometer bias is calculated and subtracted here manually, should construct an algorithm to do it automatically
+    // like the gyro and accelerometer biases
+    magbias[0] = -5.;   // User environmental x-axis correction in milliGauss
+    magbias[1] = -95.;  // User environmental y-axis correction in milliGauss
+    magbias[2] = -260.; // User environmental z-axis correction in milliGauss
+ 
+
+ while(1) {
+  
+  // If intPin goes high, all data registers have new data
+  if(MPU9150.readByte(MPU9150_ADDRESS, INT_STATUS) & 0x01) {  // On interrupt, check if data ready interrupt
+
+    MPU9150.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];  
+   
+    MPU9150.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];   
+  
+    mcount++;
+    if (mcount > 200/MagRate) {  // this is a poor man's way of setting the magnetometer read rate (see below) 
+    MPU9150.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];   
+    mcount = 0;
+    }
+  }
+   
+    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
+//  MPU9150.MadgwickQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f,  my,  mx, mz);
+  MPU9150.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 = MPU9150.readTempData();  // Read the adc values
+    temperature = ((float) tempCount) / 340.0f + 36.53f; // 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]);      
+    
+/*    lcd.clear();
+    lcd.printString("MPU9150", 0, 0);
+    lcd.printString("x   y   z", 0, 1);
+    sprintf(buffer, "%d %d %d mg", (int)(1000.0f*ax), (int)(1000.0f*ay), (int)(1000.0f*az));
+    lcd.printString(buffer, 0, 2);
+    sprintf(buffer, "%d %d %d deg/s", (int)gx, (int)gy, (int)gz);
+    lcd.printString(buffer, 0, 3);
+    sprintf(buffer, "%d %d %d mG", (int)mx, (int)my, (int)mz);
+    lcd.printString(buffer, 0, 4); 
+ */  
+  // 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);
+//    sprintf(buffer, "YPR: %f %f %f", yaw, pitch, roll);
+//    lcd.printString(buffer, 0, 4);
+//    sprintf(buffer, "rate = %f", (float) sumCount/sum);
+//    lcd.printString(buffer, 0, 5);
+    
+    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; 
+}
+}
+ 
+ }
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Sun Jun 29 22:48:08 2014 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/0b3ab51c8877
\ No newline at end of file