Diff: main.cpp

Revision:

0:65aa78c10981

Child:

1:cea9d83b8636

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Sun May 25 04:51:50 2014 +0000
@@ -0,0 +1,820 @@
+#include "mbed.h"
+
+/* MPU6050 Basic Example Code
+ by: Kris Winer
+ date: May 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  MPU-6050 basic functionality including initialization, accelerometer trimming, sleep mode functionality as well as
+ parameterizing the register addresses. Added display functions to allow display to on breadboard monitor. 
+ No DMP use. We just want to get out the accelerations, temperature, and gyro readings.
+ 
+ SDA and SCL should have external pull-up resistors (to 3.3V).
+ 10k resistors worked for me. They should be on the breakout
+ board.
+ 
+ Hardware setup:
+ MPU6050 Breakout --------- Arduino
+ 3.3V --------------------- 3.3V
+ SDA ----------------------- A4
+ SCL ----------------------- A5
+ GND ---------------------- GND
+ 
+  Note: The MPU6050 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 <Wire.h>
+//#include <Adafruit_GFX.h>
+//#include <Adafruit_PCD8544.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);
+
+// 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-6050 Register Map and Descriptions, Revision 4.0, RM-MPU-6050A-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
+//
+#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; supported in MPU-6050?
+#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_MPU6050 0x75 // Should return 0x68
+
+// Using the GY-521 breakout board, I set ADO to 0 by grounding through a 4k7 resistor
+// Seven-bit device address is 110100 for ADO = 0 and 110101 for ADO = 1
+#define ADO 0
+#if ADO
+#define MPU6050_ADDRESS 0x69  // Device address when ADO = 1
+#else
+#define MPU6050_ADDRESS 0x68  // Device address when ADO = 0
+#endif
+
+// Set up I2C
+I2C i2c(PB_9, PB_8);
+//i2c.frequency(400000);  // use fast (400 kHz) I2C
+
+// Set up serial port
+Serial pc(PA_2, PA_3); // PA_2, PA_3 on STM32F01 Nucleo
+
+Timer t;
+
+// 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
+};
+
+// Specify sensor full scale
+int Gscale = GFS_250DPS;
+int Ascale = AFS_2G;
+float aRes, gRes; // scale resolutions per LSB for the sensors
+  
+// Pin definitions
+int intPin = 12;  // These can be changed, 2 and 3 are the Arduinos ext int pins
+char blinkOn = false;
+
+int16_t accelCount[3];  // Stores the 16-bit signed accelerometer sensor output
+float ax, ay, az;       // Stores the real accel value in g's
+int16_t gyroCount[3];   // Stores the 16-bit signed gyro sensor output
+float gx, gy, gz;       // Stores the real gyro value in degrees per seconds
+float gyroBias[3] = {0, 0, 0}, accelBias[3] = {0, 0, 0}; // Bias corrections for gyro and accelerometer
+int16_t tempCount;   // Stores the real internal chip temperature in degrees Celsius
+float temperature;
+float SelfTest[6];
+
+uint32_t delt_t = 0; // used to control display output rate
+uint32_t count = 0;  // used to control display output rate
+
+// parameters for 6 DoF sensor fusion calculations
+float PI = 3.141593;
+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 * (0.0f / 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
+float pitch, yaw, roll;
+float deltat = 0.0f;                              // integration interval for both filter schemes
+uint32_t lastUpdate = 0, firstUpdate = 0;                          // used to calculate integration interval
+uint32_t Now = 0;                                 // used to calculate integration interval
+float q[4] = {1.0f, 0.0f, 0.0f, 0.0f};            // vector to hold quaternion
+
+DigitalOut myled(LED1);
+
+//===================================================================================================================
+//====== Set of useful function to access acceleratio, gyroscope, and temperature data
+//===================================================================================================================
+
+    void writeByte(uint8_t address, uint8_t subAddress, uint8_t data)
+{
+    i2c.write(address);
+    i2c.write(subAddress);
+    i2c.write(data);
+}
+
+    uint8_t readByte(uint8_t address, uint8_t subAddress)
+{
+    uint8_t data; // `data` will store the register data     
+    i2c.write(address);
+    i2c.write(subAddress);
+    data = i2c.read(1);                       // read the length byte and the 7 databytes
+    return data;                              // Return data read from slave register
+}
+
+    void readBytes(uint8_t address, uint8_t subAddress, uint8_t count, uint8_t * dest)
+{  
+    i2c.write(address);
+    i2c.write(subAddress);
+    for (int ii = 0; ii < count; ii++) {
+        dest[ii] = i2c.read(1); 
+    } 
+ 
+}
+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(MPU6050_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]);  // Read the six raw data registers into data array
+  destination[0] = (int16_t)((rawData[0] << 8) | rawData[1]) ;  // Turn the MSB and LSB into a signed 16-bit value
+  destination[1] = (int16_t)((rawData[2] << 8) | rawData[3]) ;  
+  destination[2] = (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(MPU6050_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]);  // Read the six raw data registers sequentially into data array
+  destination[0] = (int16_t)((rawData[0] << 8) | rawData[1]) ;  // Turn the MSB and LSB into a signed 16-bit value
+  destination[1] = (int16_t)((rawData[2] << 8) | rawData[3]) ;  
+  destination[2] = (int16_t)((rawData[4] << 8) | rawData[5]) ; 
+}
+
+int16_t readTempData()
+{
+  uint8_t rawData[2];  // x/y/z gyro register data stored here
+  readBytes(MPU6050_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
+}
+
+
+
+// Configure the motion detection control for low power accelerometer mode
+void LowPowerAccelOnlyMPU6050()
+{
+
+// The sensor has a high-pass filter necessary to invoke to allow the sensor motion detection algorithms work properly
+// Motion detection occurs on free-fall (acceleration below a threshold for some time for all axes), motion (acceleration
+// above a threshold for some time on at least one axis), and zero-motion toggle (acceleration on each axis less than a 
+// threshold for some time sets this flag, motion above the threshold turns it off). The high-pass filter takes gravity out
+// consideration for these threshold evaluations; otherwise, the flags would be set all the time!
+  
+  uint8_t c = readByte(MPU6050_ADDRESS, PWR_MGMT_1);
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c & ~0x30); // Clear sleep and cycle bits [5:6]
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c |  0x30); // Set sleep and cycle bits [5:6] to zero to make sure accelerometer is running
+
+  c = readByte(MPU6050_ADDRESS, PWR_MGMT_2);
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c & ~0x38); // Clear standby XA, YA, and ZA bits [3:5]
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c |  0x00); // Set XA, YA, and ZA bits [3:5] to zero to make sure accelerometer is running
+    
+  c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
+  writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x07); // Clear high-pass filter bits [2:0]
+// Set high-pass filter to 0) reset (disable), 1) 5 Hz, 2) 2.5 Hz, 3) 1.25 Hz, 4) 0.63 Hz, or 7) Hold
+  writeByte(MPU6050_ADDRESS, ACCEL_CONFIG,  c | 0x00);  // Set ACCEL_HPF to 0; reset mode disbaling high-pass filter
+
+  c = readByte(MPU6050_ADDRESS, CONFIG);
+  writeByte(MPU6050_ADDRESS, CONFIG, c & ~0x07); // Clear low-pass filter bits [2:0]
+  writeByte(MPU6050_ADDRESS, CONFIG, c |  0x00);  // Set DLPD_CFG to 0; 260 Hz bandwidth, 1 kHz rate
+    
+  c = readByte(MPU6050_ADDRESS, INT_ENABLE);
+  writeByte(MPU6050_ADDRESS, INT_ENABLE, c & ~0xFF);  // Clear all interrupts
+  writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x40);  // Enable motion threshold (bits 5) interrupt only
+  
+// Motion detection interrupt requires the absolute value of any axis to lie above the detection threshold
+// for at least the counter duration
+  writeByte(MPU6050_ADDRESS, MOT_THR, 0x80); // Set motion detection to 0.256 g; LSB = 2 mg
+  writeByte(MPU6050_ADDRESS, MOT_DUR, 0x01); // Set motion detect duration to 1  ms; LSB is 1 ms @ 1 kHz rate
+  
+  wait(0.1);  // Add delay for accumulation of samples
+  
+  c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
+  writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x07); // Clear high-pass filter bits [2:0]
+  writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c |  0x07);  // Set ACCEL_HPF to 7; hold the initial accleration value as a referance
+   
+  c = readByte(MPU6050_ADDRESS, PWR_MGMT_2);
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c & ~0xC7); // Clear standby XA, YA, and ZA bits [3:5] and LP_WAKE_CTRL bits [6:7]
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c |  0x47); // Set wakeup frequency to 5 Hz, and disable XG, YG, and ZG gyros (bits [0:2])  
+
+  c = readByte(MPU6050_ADDRESS, PWR_MGMT_1);
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c & ~0x20); // Clear sleep and cycle bit 5
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c |  0x20); // Set cycle bit 5 to begin low power accelerometer motion interrupts
+
+}
+
+
+void initMPU6050()
+{  
+ // Initialize MPU6050 device
+ // reset device
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
+  wait(0.1);
+   
+ // wake up device
+  writeByte(MPU6050_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(MPU6050_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(MPU6050_ADDRESS, CONFIG, 0x03);  
+ 
+ // Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV)
+  writeByte(MPU6050_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(MPU6050_ADDRESS, GYRO_CONFIG);
+  writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] 
+  writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
+  writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c | Gscale << 3); // Set full scale range for the gyro
+   
+ // Set accelerometer configuration
+  c =  readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
+  writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] 
+  writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
+  writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c | Ascale << 3); // Set full scale range for the accelerometer 
+
+  // 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(MPU6050_ADDRESS, INT_PIN_CFG, 0x22);    
+   writeByte(MPU6050_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 calibrateMPU6050(float * dest1, float * dest2)
+{  
+  uint8_t data[12]; // data array to hold accelerometer and gyro x, y, z, data
+  uint8_t ii, fifo_count, packet_count;
+  int16_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(MPU6050_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(MPU6050_ADDRESS, PWR_MGMT_1, 0x01);  
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_2, 0x00); 
+  wait(0.2);
+  
+// Configure device for bias calculation
+  writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x00);   // Disable all interrupts
+  writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00);      // Disable FIFO
+  writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00);   // Turn on internal clock source
+  writeByte(MPU6050_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master
+  writeByte(MPU6050_ADDRESS, USER_CTRL, 0x00);    // Disable FIFO and I2C master modes
+  writeByte(MPU6050_ADDRESS, USER_CTRL, 0x0C);    // Reset FIFO and DMP
+  wait(0.015);
+  
+// Configure MPU6050 gyro and accelerometer for bias calculation
+  writeByte(MPU6050_ADDRESS, CONFIG, 0x01);      // Set low-pass filter to 188 Hz
+  writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x00);  // Set sample rate to 1 kHz
+  writeByte(MPU6050_ADDRESS, GYRO_CONFIG, 0x00);  // Set gyro full-scale to 250 degrees per second, maximum sensitivity
+  writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity
+  wait(0.2);
+ 
+  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(MPU6050_ADDRESS, USER_CTRL, 0x40);   // Enable FIFO  
+  writeByte(MPU6050_ADDRESS, FIFO_EN, 0x78);     // Enable gyro and accelerometer sensors for FIFO  (max size 1024 bytes in MPU-6050)
+  wait(0.08); // accumulate 80 samples in 80 milliseconds = 960 bytes
+
+// At end of sample accumulation, turn off FIFO sensor read
+  writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00);        // Disable gyro and accelerometer sensors for FIFO
+  readBytes(MPU6050_ADDRESS, FIFO_COUNTH, 2, data); // 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++) {
+    readBytes(MPU6050_ADDRESS, FIFO_R_W, 12, data); // read data for averaging
+    accel_bias[0] += (((int16_t)data[0] << 8) | data[1]  ) ; // Divide sum of FIFO gyro data by number of samples
+    accel_bias[1] += (((int16_t)data[2] << 8) | data[3]  ) ;
+    accel_bias[2] += (((int16_t)data[4] << 8) | data[5]  ) - accelsensitivity; // Assumes device facing up!
+    gyro_bias[0]  += (((int16_t)data[6] << 8) | data[7]  ) ;
+    gyro_bias[1]  += (((int16_t)data[8] << 8) | data[9]  ) ;
+    gyro_bias[2]  += (((int16_t)data[10] << 8) | data[11]) ;
+}
+
+    accel_bias[0] /= packet_count;  // Normalize sums to get average count biases
+    accel_bias[1] /= packet_count;
+    accel_bias[2] /= packet_count;
+    gyro_bias[0]  /= packet_count;
+    gyro_bias[1]  /= packet_count;
+    gyro_bias[2]  /= packet_count;
+
+// 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(MPU6050_ADDRESS, XG_OFFS_USRH, data[0]); // might not be supported in MPU6050
+//  writeByte(MPU6050_ADDRESS, XG_OFFS_USRL, data[1]);
+//  writeByte(MPU6050_ADDRESS, YG_OFFS_USRH, data[2]);
+//  writeByte(MPU6050_ADDRESS, YG_OFFS_USRL, data[3]);
+//  writeByte(MPU6050_ADDRESS, ZG_OFFS_USRH, data[4]);
+//  writeByte(MPU6050_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.
+
+  int16_t accel_bias_reg[3] = {0, 0, 0}; // A place to hold the factory accelerometer trim biases
+  readBytes(MPU6050_ADDRESS, XA_OFFSET_H, 2, &data[0]); // Read factory accelerometer trim values
+  accel_bias_reg[0] = ((int16_t)data[0] << 8) | data[1];
+  readBytes(MPU6050_ADDRESS, YA_OFFSET_H, 2, &data[0]);
+  accel_bias_reg[1] = ((int16_t)data[0] << 8) | data[1];
+  readBytes(MPU6050_ADDRESS, ZA_OFFSET_H, 2, &data[0]);
+  accel_bias_reg[2] = ((int16_t)data[0] << 8) | data[1];
+  
+  int16_t mask = 0x0001; // 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
+ 
+  // Push accelerometer biases to hardware registers
+//  writeByte(MPU6050_ADDRESS, XA_OFFSET_H, data[0]); // might not be supported in MPU6050
+//  writeByte(MPU6050_ADDRESS, XA_OFFSET_L_TC, data[1]);
+//  writeByte(MPU6050_ADDRESS, YA_OFFSET_H, data[2]);
+//  writeByte(MPU6050_ADDRESS, YA_OFFSET_L_TC, data[3]);
+//  writeByte(MPU6050_ADDRESS, ZA_OFFSET_H, data[4]);
+//  writeByte(MPU6050_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 MPU6050SelfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass
+{
+   uint8_t rawData[4];
+   uint8_t selfTest[6];
+   float factoryTrim[6];
+   
+   // Configure the accelerometer for self-test
+   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0xF0); // Enable self test on all three axes and set accelerometer range to +/- 8 g
+   writeByte(MPU6050_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(MPU6050_ADDRESS, SELF_TEST_X); // X-axis self-test results
+   rawData[1] = readByte(MPU6050_ADDRESS, SELF_TEST_Y); // Y-axis self-test results
+   rawData[2] = readByte(MPU6050_ADDRESS, SELF_TEST_Z); // Z-axis self-test results
+   rawData[3] = readByte(MPU6050_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] = (4096.0*0.34)*(pow( (0.92/0.34) , ((selfTest[0] - 1.0)/30.0))); // FT[Xa] factory trim calculation
+   factoryTrim[1] = (4096.0*0.34)*(pow( (0.92/0.34) , ((selfTest[1] - 1.0)/30.0))); // FT[Ya] factory trim calculation
+   factoryTrim[2] = (4096.0*0.34)*(pow( (0.92/0.34) , ((selfTest[2] - 1.0)/30.0))); // FT[Za] factory trim calculation
+   factoryTrim[3] =  ( 25.0*131.0)*(pow( 1.046 , (selfTest[3] - 1.0) ));             // FT[Xg] factory trim calculation
+   factoryTrim[4] =  (-25.0*131.0)*(pow( 1.046 , (selfTest[4] - 1.0) ));             // FT[Yg] factory trim calculation
+   factoryTrim[5] =  ( 25.0*131.0)*(pow( 1.046 , (selfTest[5] - 1.0) ));             // 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] = 100.0 + 100.0*(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 and rotation rate to produce a quaternion-based estimate of relative
+// 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 q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3];         // short name local variable for readability
+            float norm;                                               // vector norm
+            float f1, f2, f3;                                         // objetive funcyion elements
+            float J_11or24, J_12or23, J_13or22, J_14or21, J_32, J_33; // objective function Jacobian elements
+            float qDot1, qDot2, qDot3, qDot4;
+            float hatDot1, hatDot2, hatDot3, hatDot4;
+            float gerrx, gerry, gerrz, gbiasx, gbiasy, gbiasz;        // gyro bias error
+
+            // Auxiliary variables to avoid repeated arithmetic
+            float _halfq1 = 0.5f * q1;
+            float _halfq2 = 0.5f * q2;
+            float _halfq3 = 0.5f * q3;
+            float _halfq4 = 0.5f * q4;
+            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;
+
+            // 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;
+            
+            // Compute the objective function and Jacobian
+            f1 = _2q2 * q4 - _2q1 * q3 - ax;
+            f2 = _2q1 * q2 + _2q3 * q4 - ay;
+            f3 = 1.0f - _2q2 * q2 - _2q3 * q3 - az;
+            J_11or24 = _2q3;
+            J_12or23 = _2q4;
+            J_13or22 = _2q1;
+            J_14or21 = _2q2;
+            J_32 = 2.0f * J_14or21;
+            J_33 = 2.0f * J_11or24;
+          
+            // Compute the gradient (matrix multiplication)
+            hatDot1 = J_14or21 * f2 - J_11or24 * f1;
+            hatDot2 = J_12or23 * f1 + J_13or22 * f2 - J_32 * f3;
+            hatDot3 = J_12or23 * f2 - J_33 *f3 - J_13or22 * f1;
+            hatDot4 = J_14or21 * f1 + J_11or24 * f2;
+            
+            // Normalize the gradient
+            norm = sqrt(hatDot1 * hatDot1 + hatDot2 * hatDot2 + hatDot3 * hatDot3 + hatDot4 * hatDot4);
+            hatDot1 /= norm;
+            hatDot2 /= norm;
+            hatDot3 /= norm;
+            hatDot4 /= norm;
+            
+            // Compute estimated gyroscope biases
+            gerrx = _2q1 * hatDot2 - _2q2 * hatDot1 - _2q3 * hatDot4 + _2q4 * hatDot3;
+            gerry = _2q1 * hatDot3 + _2q2 * hatDot4 - _2q3 * hatDot1 - _2q4 * hatDot2;
+            gerrz = _2q1 * hatDot4 - _2q2 * hatDot3 + _2q3 * hatDot2 - _2q4 * hatDot1;
+            
+            // Compute and remove gyroscope biases
+            gbiasx += gerrx * deltat * zeta;
+            gbiasy += gerry * deltat * zeta;
+            gbiasz += gerrz * deltat * zeta;
+            gx -= gbiasx;
+            gy -= gbiasy;
+            gz -= gbiasz;
+            
+            // Compute the quaternion derivative
+            qDot1 = -_halfq2 * gx - _halfq3 * gy - _halfq4 * gz;
+            qDot2 =  _halfq1 * gx + _halfq3 * gz - _halfq4 * gy;
+            qDot3 =  _halfq1 * gy - _halfq2 * gz + _halfq4 * gx;
+            qDot4 =  _halfq1 * gz + _halfq2 * gy - _halfq3 * gx;
+
+            // Compute then integrate estimated quaternion derivative
+            q1 += (qDot1 -(beta * hatDot1)) * deltat;
+            q2 += (qDot2 -(beta * hatDot2)) * deltat;
+            q3 += (qDot3 -(beta * hatDot3)) * deltat;
+            q4 += (qDot4 -(beta * hatDot4)) * deltat;
+
+            // Normalize the quaternion
+            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 setup()
+{
+    
+  // Read the WHO_AM_I register, this is a good test of communication
+  uint8_t c = readByte(MPU6050_ADDRESS, WHO_AM_I_MPU6050);  // Read WHO_AM_I register for MPU-6050
+
+  if (c == 0x68) // WHO_AM_I should always be 0x68
+  {  
+    pc.printf("MPU6050 is online...");
+    
+    MPU6050SelfTest(SelfTest); // Start by performing self test and reporting values
+    pc.printf("x-axis self test: acceleration trim within : "); pc.printf("%f", SelfTest[0]); pc.printf("% of factory value");
+    pc.printf("y-axis self test: acceleration trim within : "); pc.printf("%f", SelfTest[1]); pc.printf("% of factory value");
+    pc.printf("z-axis self test: acceleration trim within : "); pc.printf("%f", SelfTest[2]); pc.printf("% of factory value");
+    pc.printf("x-axis self test: gyration trim within : "); pc.printf("%f", SelfTest[3]); pc.printf("% of factory value");
+    pc.printf("y-axis self test: gyration trim within : "); pc.printf("%f", SelfTest[4]); pc.printf("% of factory value");
+    pc.printf("z-axis self test: gyration trim within : "); pc.printf("%f", SelfTest[5]); pc.printf("% of factory value");
+
+    if(SelfTest[0] < 1.0f && SelfTest[1] < 1.0f && SelfTest[2] < 1.0f && SelfTest[3] < 1.0f && SelfTest[4] < 1.0f && SelfTest[5] < 1.0f) {
+  
+    calibrateMPU6050(gyroBias, accelBias); // Calibrate gyro and accelerometers, load biases in bias registers  
+    initMPU6050(); pc.printf("MPU6050 initialized for active data mode...."); // Initialize device for active mode read of acclerometer, gyroscope, and temperature
+   }
+   else
+   {
+    pc.printf("Could not connect to MPU6050: 0x");
+    pc.printf("%h", c);
+    while(1) ; // Loop forever if communication doesn't happen
+    }
+}
+}
+
+
+int main() 
+{
+       // If data ready bit set, all data registers have new data
+  if(readByte(MPU6050_ADDRESS, INT_STATUS) & 0x01) {  // check if data ready interrupt
+    readAccelData(accelCount);  // Read the x/y/z adc values
+    getAres();
+    
+    // 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
+    getGres();
+ 
+    // 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];   
+
+    tempCount = readTempData();  // Read the x/y/z adc values
+    temperature = (tempCount) / 340. + 36.53; // Temperature in degrees Centigrade
+   }  
+   
+    Now = t.read_us();
+    deltat = ((Now - lastUpdate)/1000000.0f); // set integration time by time elapsed since last filter update
+    lastUpdate = Now;
+    if(lastUpdate - firstUpdate > 10000000.0f) {
+      beta = 0.04;  // decrease filter gain after stabilized
+      zeta = 0.015; // increaseyro bias drift gain after stabilized
+    }
+   // Pass gyro rate as rad/s
+    MadgwickQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f);
+
+    // 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
+ //   DigitalOut(LED1);
+ 
+    pc.printf("ax = "); pc.printf("%i", 1000*ax);  
+    pc.printf(" ay = "); pc.printf("%i", 1000*ay); 
+    pc.printf(" az = "); pc.printf("%i", 1000*az); pc.printf(" mg");
+
+    pc.printf("gx = "); pc.printf("%f", gx); 
+    pc.printf(" gy = "); pc.printf("%f", gy); 
+    pc.printf(" gz = "); pc.printf("%f", gz); pc.printf(" deg/s");
+    
+    pc.printf("q0 = "); pc.printf("%f", q[0]);
+    pc.printf(" qx = "); pc.printf("%f", q[1]); 
+    pc.printf(" qy = "); pc.printf("%f", q[2]); 
+    pc.printf(" qz = "); pc.printf("%f", 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; 
+    roll  *= 180.0f / PI;
+
+    pc.printf("Yaw, Pitch, Roll: ");
+    pc.printf("%f", yaw);
+    pc.printf(", ");
+    pc.printf("%f", pitch);
+    pc.printf(", ");
+    pc.printf("%f", roll);
+
+    pc.printf("average rate = "); pc.printf("%f", (1.0f/deltat)); pc.printf(" Hz");
+    
+    
+    blinkOn = ~blinkOn;
+    count = t.read_ms();  
+}
+    while(1) {
+        myled = !myled;
+        wait(1);
+    }
+}