MPU6050.h

00001 #ifndef MPU6050_H
00002 #define MPU6050_H
00003  
00004 #include "mbed.h"
00005 #include "math.h"
00006  
00007  // Define registers per MPU6050, Register Map and Descriptions, 6 DOF Motion sensor fusion device
00008 // See also MPU-6050 Register Map and Descriptions, Revision 4.0, RM-MPU-6050A-00, 9/12/2012 for registers not listed in 
00009 // above document; the MPU6050 and MPU 9150 are virtually identical but the latter has an on-board magnetic sensor
00010 //
00011 #define XGOFFS_TC        0x00 // Bit 7 PWR_MODE, bits 6:1 XG_OFFS_TC, bit 0 OTP_BNK_VLD                 
00012 #define YGOFFS_TC        0x01                                                                          
00013 #define ZGOFFS_TC        0x02
00014 #define X_FINE_GAIN      0x03 // [7:0] fine gain
00015 #define Y_FINE_GAIN      0x04
00016 #define Z_FINE_GAIN      0x05
00017 #define XA_OFFSET_H      0x06 // User-defined trim values for accelerometer
00018 #define XA_OFFSET_L_TC   0x07
00019 #define YA_OFFSET_H      0x08
00020 #define YA_OFFSET_L_TC   0x09
00021 #define ZA_OFFSET_H      0x0A
00022 #define ZA_OFFSET_L_TC   0x0B
00023 #define SELF_TEST_X      0x0D
00024 #define SELF_TEST_Y      0x0E    
00025 #define SELF_TEST_Z      0x0F
00026 #define SELF_TEST_A      0x10
00027 #define XG_OFFS_USRH     0x13  // User-defined trim values for gyroscope; supported in MPU-6050?
00028 #define XG_OFFS_USRL     0x14
00029 #define YG_OFFS_USRH     0x15
00030 #define YG_OFFS_USRL     0x16
00031 #define ZG_OFFS_USRH     0x17
00032 #define ZG_OFFS_USRL     0x18
00033 #define SMPLRT_DIV       0x19
00034 #define CONFIG           0x1A
00035 #define GYRO_CONFIG      0x1B
00036 #define ACCEL_CONFIG     0x1C
00037 #define FF_THR           0x1D  // Free-fall
00038 #define FF_DUR           0x1E  // Free-fall
00039 #define MOT_THR          0x1F  // Motion detection threshold bits [7:0]
00040 #define MOT_DUR          0x20  // Duration counter threshold for motion interrupt generation, 1 kHz rate, LSB = 1 ms
00041 #define ZMOT_THR         0x21  // Zero-motion detection threshold bits [7:0]
00042 #define ZRMOT_DUR        0x22  // Duration counter threshold for zero motion interrupt generation, 16 Hz rate, LSB = 64 ms
00043 #define FIFO_EN          0x23
00044 #define I2C_MST_CTRL     0x24   
00045 #define I2C_SLV0_ADDR    0x25
00046 #define I2C_SLV0_REG     0x26
00047 #define I2C_SLV0_CTRL    0x27
00048 #define I2C_SLV1_ADDR    0x28
00049 #define I2C_SLV1_REG     0x29
00050 #define I2C_SLV1_CTRL    0x2A
00051 #define I2C_SLV2_ADDR    0x2B
00052 #define I2C_SLV2_REG     0x2C
00053 #define I2C_SLV2_CTRL    0x2D
00054 #define I2C_SLV3_ADDR    0x2E
00055 #define I2C_SLV3_REG     0x2F
00056 #define I2C_SLV3_CTRL    0x30
00057 #define I2C_SLV4_ADDR    0x31
00058 #define I2C_SLV4_REG     0x32
00059 #define I2C_SLV4_DO      0x33
00060 #define I2C_SLV4_CTRL    0x34
00061 #define I2C_SLV4_DI      0x35
00062 #define I2C_MST_STATUS   0x36
00063 #define INT_PIN_CFG      0x37
00064 #define INT_ENABLE       0x38
00065 #define DMP_INT_STATUS   0x39  // Check DMP interrupt
00066 #define INT_STATUS       0x3A
00067 #define ACCEL_XOUT_H     0x3B
00068 #define ACCEL_XOUT_L     0x3C
00069 #define ACCEL_YOUT_H     0x3D
00070 #define ACCEL_YOUT_L     0x3E
00071 #define ACCEL_ZOUT_H     0x3F
00072 #define ACCEL_ZOUT_L     0x40
00073 #define TEMP_OUT_H       0x41
00074 #define TEMP_OUT_L       0x42
00075 #define GYRO_XOUT_H      0x43
00076 #define GYRO_XOUT_L      0x44
00077 #define GYRO_YOUT_H      0x45
00078 #define GYRO_YOUT_L      0x46
00079 #define GYRO_ZOUT_H      0x47
00080 #define GYRO_ZOUT_L      0x48
00081 #define EXT_SENS_DATA_00 0x49
00082 #define EXT_SENS_DATA_01 0x4A
00083 #define EXT_SENS_DATA_02 0x4B
00084 #define EXT_SENS_DATA_03 0x4C
00085 #define EXT_SENS_DATA_04 0x4D
00086 #define EXT_SENS_DATA_05 0x4E
00087 #define EXT_SENS_DATA_06 0x4F
00088 #define EXT_SENS_DATA_07 0x50
00089 #define EXT_SENS_DATA_08 0x51
00090 #define EXT_SENS_DATA_09 0x52
00091 #define EXT_SENS_DATA_10 0x53
00092 #define EXT_SENS_DATA_11 0x54
00093 #define EXT_SENS_DATA_12 0x55
00094 #define EXT_SENS_DATA_13 0x56
00095 #define EXT_SENS_DATA_14 0x57
00096 #define EXT_SENS_DATA_15 0x58
00097 #define EXT_SENS_DATA_16 0x59
00098 #define EXT_SENS_DATA_17 0x5A
00099 #define EXT_SENS_DATA_18 0x5B
00100 #define EXT_SENS_DATA_19 0x5C
00101 #define EXT_SENS_DATA_20 0x5D
00102 #define EXT_SENS_DATA_21 0x5E
00103 #define EXT_SENS_DATA_22 0x5F
00104 #define EXT_SENS_DATA_23 0x60
00105 #define MOT_DETECT_STATUS 0x61
00106 #define I2C_SLV0_DO      0x63
00107 #define I2C_SLV1_DO      0x64
00108 #define I2C_SLV2_DO      0x65
00109 #define I2C_SLV3_DO      0x66
00110 #define I2C_MST_DELAY_CTRL 0x67
00111 #define SIGNAL_PATH_RESET  0x68
00112 #define MOT_DETECT_CTRL   0x69
00113 #define USER_CTRL        0x6A  // Bit 7 enable DMP, bit 3 reset DMP
00114 #define PWR_MGMT_1       0x6B // Device defaults to the SLEEP mode
00115 #define PWR_MGMT_2       0x6C
00116 #define DMP_BANK         0x6D  // Activates a specific bank in the DMP
00117 #define DMP_RW_PNT       0x6E  // Set read/write pointer to a specific start address in specified DMP bank
00118 #define DMP_REG          0x6F  // Register in DMP from which to read or to which to write
00119 #define DMP_REG_1        0x70
00120 #define DMP_REG_2        0x71
00121 #define FIFO_COUNTH      0x72
00122 #define FIFO_COUNTL      0x73
00123 #define FIFO_R_W         0x74
00124 #define WHO_AM_I_MPU6050 0x75 // Should return 0x68
00125 
00126 // Using the GY-521 breakout board, I set ADO to 0 by grounding through a 4k7 resistor
00127 // Seven-bit device address is 110100 for ADO = 0 and 110101 for ADO = 1
00128 #define ADO 0
00129 #if ADO
00130 #define MPU6050_ADDRESS 0x69<<1  // Device address when ADO = 1
00131 #else
00132 #define MPU6050_ADDRESS 0x68<<1  // Device address when ADO = 0
00133 #endif
00134 
00135 // Set initial input parameters
00136 enum Ascale {
00137   AFS_2G = 0,
00138   AFS_4G,
00139   AFS_8G,
00140   AFS_16G
00141 };
00142 
00143 enum Gscale {
00144   GFS_250DPS = 0,
00145   GFS_500DPS,
00146   GFS_1000DPS,
00147   GFS_2000DPS
00148 };
00149 
00150 // Specify sensor full scale
00151 int Gscale = GFS_250DPS;
00152 int Ascale = AFS_2G;
00153 
00154 //Set up I2C, (SDA,SCL)
00155 I2C i2c(I2C_SDA, I2C_SCL);
00156 
00157 DigitalOut myled(LED1);
00158    
00159 float aRes, gRes; // scale resolutions per LSB for the sensors
00160   
00161 // Pin definitions
00162 int intPin = 12;  // These can be changed, 2 and 3 are the Arduinos ext int pins
00163 
00164 int16_t accelCount[3];  // Stores the 16-bit signed accelerometer sensor output
00165 float ax, ay, az;       // Stores the real accel value in g's
00166 int16_t gyroCount[3];   // Stores the 16-bit signed gyro sensor output
00167 float gx, gy, gz;       // Stores the real gyro value in degrees per seconds
00168 float gyroBias[3] = {0, 0, 0}, accelBias[3] = {0, 0, 0}; // Bias corrections for gyro and accelerometer
00169 int16_t tempCount;   // Stores the real internal chip temperature in degrees Celsius
00170 float temperature;
00171 float SelfTest[6];
00172 
00173 int delt_t = 0; // used to control display output rate
00174 int count = 0;  // used to control display output rate
00175 
00176 // parameters for 6 DoF sensor fusion calculations
00177 float PI = 3.14159265358979323846f;
00178 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
00179 float beta = sqrt(3.0f / 4.0f) * GyroMeasError;  // compute beta
00180 float GyroMeasDrift = PI * (1.0f / 180.0f);      // gyroscope measurement drift in rad/s/s (start at 0.0 deg/s/s)
00181 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
00182 float pitch, yaw, roll;
00183 float deltat = 0.0f;                              // integration interval for both filter schemes
00184 int lastUpdate = 0, firstUpdate = 0, Now = 0;     // used to calculate integration interval                               // used to calculate integration interval
00185 float q[4] = {1.0f, 0.0f, 0.0f, 0.0f};            // vector to hold quaternion
00186 
00187 class MPU6050 {
00188  
00189     protected:
00190  
00191     public:
00192   //===================================================================================================================
00193 //====== Set of useful function to access acceleratio, gyroscope, and temperature data
00194 //===================================================================================================================
00195 
00196     void writeByte(uint8_t address, uint8_t subAddress, uint8_t data)
00197 {
00198    char data_write[2];
00199    data_write[0] = subAddress;
00200    data_write[1] = data;
00201    i2c.write(address, data_write, 2, 0);
00202 }
00203 
00204     char readByte(uint8_t address, uint8_t subAddress)
00205 {
00206     char data[1]; // `data` will store the register data     
00207     char data_write[1];
00208     data_write[0] = subAddress;
00209     i2c.write(address, data_write, 1, 1); // no stop
00210     i2c.read(address, data, 1, 0); 
00211     return data[0]; 
00212 }
00213 
00214     void readBytes(uint8_t address, uint8_t subAddress, uint8_t count, uint8_t * dest)
00215 {     
00216     char data[14];
00217     char data_write[1];
00218     data_write[0] = subAddress;
00219     i2c.write(address, data_write, 1, 1); // no stop
00220     i2c.read(address, data, count, 0); 
00221     for(int ii = 0; ii < count; ii++) {
00222      dest[ii] = data[ii];
00223     }
00224 } 
00225  
00226 
00227 void getGres() {
00228   switch (Gscale)
00229   {
00230     // Possible gyro scales (and their register bit settings) are:
00231     // 250 DPS (00), 500 DPS (01), 1000 DPS (10), and 2000 DPS  (11). 
00232         // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value:
00233     case GFS_250DPS:
00234           gRes = 250.0/32768.0;
00235           break;
00236     case GFS_500DPS:
00237           gRes = 500.0/32768.0;
00238           break;
00239     case GFS_1000DPS:
00240           gRes = 1000.0/32768.0;
00241           break;
00242     case GFS_2000DPS:
00243           gRes = 2000.0/32768.0;
00244           break;
00245   }
00246 }
00247 
00248 void getAres() {
00249   switch (Ascale)
00250   {
00251     // Possible accelerometer scales (and their register bit settings) are:
00252     // 2 Gs (00), 4 Gs (01), 8 Gs (10), and 16 Gs  (11). 
00253         // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value:
00254     case AFS_2G:
00255           aRes = 2.0/32768.0;
00256           break;
00257     case AFS_4G:
00258           aRes = 4.0/32768.0;
00259           break;
00260     case AFS_8G:
00261           aRes = 8.0/32768.0;
00262           break;
00263     case AFS_16G:
00264           aRes = 16.0/32768.0;
00265           break;
00266   }
00267 }
00268 
00269 
00270 void readAccelData(int16_t * destination)
00271 {
00272   uint8_t rawData[6];  // x/y/z accel register data stored here
00273   readBytes(MPU6050_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]);  // Read the six raw data registers into data array
00274   destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ;  // Turn the MSB and LSB into a signed 16-bit value
00275   destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;  
00276   destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 
00277 }
00278 
00279 void readGyroData(int16_t * destination)
00280 {
00281   uint8_t rawData[6];  // x/y/z gyro register data stored here
00282   readBytes(MPU6050_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]);  // Read the six raw data registers sequentially into data array
00283   destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ;  // Turn the MSB and LSB into a signed 16-bit value
00284   destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;  
00285   destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 
00286 }
00287 
00288 int16_t readTempData()
00289 {
00290   uint8_t rawData[2];  // x/y/z gyro register data stored here
00291   readBytes(MPU6050_ADDRESS, TEMP_OUT_H, 2, &rawData[0]);  // Read the two raw data registers sequentially into data array 
00292   return (int16_t)(((int16_t)rawData[0]) << 8 | rawData[1]) ;  // Turn the MSB and LSB into a 16-bit value
00293 }
00294 
00295 
00296 
00297 // Configure the motion detection control for low power accelerometer mode
00298 void LowPowerAccelOnly()
00299 {
00300 
00301 // The sensor has a high-pass filter necessary to invoke to allow the sensor motion detection algorithms work properly
00302 // Motion detection occurs on free-fall (acceleration below a threshold for some time for all axes), motion (acceleration
00303 // above a threshold for some time on at least one axis), and zero-motion toggle (acceleration on each axis less than a 
00304 // threshold for some time sets this flag, motion above the threshold turns it off). The high-pass filter takes gravity out
00305 // consideration for these threshold evaluations; otherwise, the flags would be set all the time!
00306   
00307   uint8_t c = readByte(MPU6050_ADDRESS, PWR_MGMT_1);
00308   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c & ~0x30); // Clear sleep and cycle bits [5:6]
00309   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c |  0x30); // Set sleep and cycle bits [5:6] to zero to make sure accelerometer is running
00310 
00311   c = readByte(MPU6050_ADDRESS, PWR_MGMT_2);
00312   writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c & ~0x38); // Clear standby XA, YA, and ZA bits [3:5]
00313   writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c |  0x00); // Set XA, YA, and ZA bits [3:5] to zero to make sure accelerometer is running
00314     
00315   c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
00316   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x07); // Clear high-pass filter bits [2:0]
00317 // 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
00318   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG,  c | 0x00);  // Set ACCEL_HPF to 0; reset mode disbaling high-pass filter
00319 
00320   c = readByte(MPU6050_ADDRESS, CONFIG);
00321   writeByte(MPU6050_ADDRESS, CONFIG, c & ~0x07); // Clear low-pass filter bits [2:0]
00322   writeByte(MPU6050_ADDRESS, CONFIG, c |  0x00);  // Set DLPD_CFG to 0; 260 Hz bandwidth, 1 kHz rate
00323     
00324   c = readByte(MPU6050_ADDRESS, INT_ENABLE);
00325   writeByte(MPU6050_ADDRESS, INT_ENABLE, c & ~0xFF);  // Clear all interrupts
00326   writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x40);  // Enable motion threshold (bits 5) interrupt only
00327   
00328 // Motion detection interrupt requires the absolute value of any axis to lie above the detection threshold
00329 // for at least the counter duration
00330   writeByte(MPU6050_ADDRESS, MOT_THR, 0x80); // Set motion detection to 0.256 g; LSB = 2 mg
00331   writeByte(MPU6050_ADDRESS, MOT_DUR, 0x01); // Set motion detect duration to 1  ms; LSB is 1 ms @ 1 kHz rate
00332   
00333   wait(0.1);  // Add delay for accumulation of samples
00334   
00335   c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
00336   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x07); // Clear high-pass filter bits [2:0]
00337   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c |  0x07);  // Set ACCEL_HPF to 7; hold the initial accleration value as a referance
00338    
00339   c = readByte(MPU6050_ADDRESS, PWR_MGMT_2);
00340   writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c & ~0xC7); // Clear standby XA, YA, and ZA bits [3:5] and LP_WAKE_CTRL bits [6:7]
00341   writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c |  0x47); // Set wakeup frequency to 5 Hz, and disable XG, YG, and ZG gyros (bits [0:2])  
00342 
00343   c = readByte(MPU6050_ADDRESS, PWR_MGMT_1);
00344   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c & ~0x20); // Clear sleep and cycle bit 5
00345   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c |  0x20); // Set cycle bit 5 to begin low power accelerometer motion interrupts
00346 
00347 }
00348 
00349 
00350 void resetMPU6050() {
00351   // reset device
00352   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
00353   wait(0.1);
00354   }
00355   
00356   
00357 void initMPU6050()
00358 {  
00359  // Initialize MPU6050 device
00360  // wake up device
00361   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00); // Clear sleep mode bit (6), enable all sensors 
00362   wait(0.1); // Delay 100 ms for PLL to get established on x-axis gyro; should check for PLL ready interrupt  
00363 
00364  // get stable time source
00365   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01);  // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001
00366 
00367  // Configure Gyro and Accelerometer
00368  // Disable FSYNC and set accelerometer and gyro bandwidth to 44 and 42 Hz, respectively; 
00369  // DLPF_CFG = bits 2:0 = 010; this sets the sample rate at 1 kHz for both
00370  // Maximum delay is 4.9 ms which is just over a 200 Hz maximum rate
00371   writeByte(MPU6050_ADDRESS, CONFIG, 0x03);  
00372  
00373  // Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV)
00374   writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x04);  // Use a 200 Hz rate; the same rate set in CONFIG above
00375  
00376  // Set gyroscope full scale range
00377  // Range selects FS_SEL and AFS_SEL are 0 - 3, so 2-bit values are left-shifted into positions 4:3
00378   uint8_t c =  readByte(MPU6050_ADDRESS, GYRO_CONFIG);
00379   writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] 
00380   writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
00381   writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c | Gscale << 3); // Set full scale range for the gyro
00382    
00383  // Set accelerometer configuration
00384   c =  readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
00385   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] 
00386   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
00387   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c | Ascale << 3); // Set full scale range for the accelerometer 
00388 
00389   // Configure Interrupts and Bypass Enable
00390   // Set interrupt pin active high, push-pull, and clear on read of INT_STATUS, enable I2C_BYPASS_EN so additional chips 
00391   // can join the I2C bus and all can be controlled by the Arduino as master
00392    writeByte(MPU6050_ADDRESS, INT_PIN_CFG, 0x22);    
00393    writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x01);  // Enable data ready (bit 0) interrupt
00394 }
00395 
00396 // Function which accumulates gyro and accelerometer data after device initialization. It calculates the average
00397 // of the at-rest readings and then loads the resulting offsets into accelerometer and gyro bias registers.
00398 void calibrateMPU6050(float * dest1, float * dest2)
00399 {  
00400   uint8_t data[12]; // data array to hold accelerometer and gyro x, y, z, data
00401   uint16_t ii, packet_count, fifo_count;
00402   int32_t gyro_bias[3] = {0, 0, 0}, accel_bias[3] = {0, 0, 0};
00403   
00404 // reset device, reset all registers, clear gyro and accelerometer bias registers
00405   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
00406   wait(0.1);  
00407    
00408 // get stable time source
00409 // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001
00410   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01);  
00411   writeByte(MPU6050_ADDRESS, PWR_MGMT_2, 0x00); 
00412   wait(0.2);
00413   
00414 // Configure device for bias calculation
00415   writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x00);   // Disable all interrupts
00416   writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00);      // Disable FIFO
00417   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00);   // Turn on internal clock source
00418   writeByte(MPU6050_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master
00419   writeByte(MPU6050_ADDRESS, USER_CTRL, 0x00);    // Disable FIFO and I2C master modes
00420   writeByte(MPU6050_ADDRESS, USER_CTRL, 0x0C);    // Reset FIFO and DMP
00421   wait(0.015);
00422   
00423 // Configure MPU6050 gyro and accelerometer for bias calculation
00424   writeByte(MPU6050_ADDRESS, CONFIG, 0x01);      // Set low-pass filter to 188 Hz
00425   writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x00);  // Set sample rate to 1 kHz
00426   writeByte(MPU6050_ADDRESS, GYRO_CONFIG, 0x00);  // Set gyro full-scale to 250 degrees per second, maximum sensitivity
00427   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity
00428  
00429   uint16_t  gyrosensitivity  = 131;   // = 131 LSB/degrees/sec
00430   uint16_t  accelsensitivity = 16384;  // = 16384 LSB/g
00431 
00432 // Configure FIFO to capture accelerometer and gyro data for bias calculation
00433   writeByte(MPU6050_ADDRESS, USER_CTRL, 0x40);   // Enable FIFO  
00434   writeByte(MPU6050_ADDRESS, FIFO_EN, 0x78);     // Enable gyro and accelerometer sensors for FIFO  (max size 1024 bytes in MPU-6050)
00435   wait(0.08); // accumulate 80 samples in 80 milliseconds = 960 bytes
00436 
00437 // At end of sample accumulation, turn off FIFO sensor read
00438   writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00);        // Disable gyro and accelerometer sensors for FIFO
00439   readBytes(MPU6050_ADDRESS, FIFO_COUNTH, 2, &data[0]); // read FIFO sample count
00440   fifo_count = ((uint16_t)data[0] << 8) | data[1];
00441   packet_count = fifo_count/12;// How many sets of full gyro and accelerometer data for averaging
00442 
00443   for (ii = 0; ii < packet_count; ii++) {
00444     int16_t accel_temp[3] = {0, 0, 0}, gyro_temp[3] = {0, 0, 0};
00445     readBytes(MPU6050_ADDRESS, FIFO_R_W, 12, &data[0]); // read data for averaging
00446     accel_temp[0] = (int16_t) (((int16_t)data[0] << 8) | data[1]  ) ;  // Form signed 16-bit integer for each sample in FIFO
00447     accel_temp[1] = (int16_t) (((int16_t)data[2] << 8) | data[3]  ) ;
00448     accel_temp[2] = (int16_t) (((int16_t)data[4] << 8) | data[5]  ) ;    
00449     gyro_temp[0]  = (int16_t) (((int16_t)data[6] << 8) | data[7]  ) ;
00450     gyro_temp[1]  = (int16_t) (((int16_t)data[8] << 8) | data[9]  ) ;
00451     gyro_temp[2]  = (int16_t) (((int16_t)data[10] << 8) | data[11]) ;
00452     
00453     accel_bias[0] += (int32_t) accel_temp[0]; // Sum individual signed 16-bit biases to get accumulated signed 32-bit biases
00454     accel_bias[1] += (int32_t) accel_temp[1];
00455     accel_bias[2] += (int32_t) accel_temp[2];
00456     gyro_bias[0]  += (int32_t) gyro_temp[0];
00457     gyro_bias[1]  += (int32_t) gyro_temp[1];
00458     gyro_bias[2]  += (int32_t) gyro_temp[2];
00459             
00460 }
00461     accel_bias[0] /= (int32_t) packet_count; // Normalize sums to get average count biases
00462     accel_bias[1] /= (int32_t) packet_count;
00463     accel_bias[2] /= (int32_t) packet_count;
00464     gyro_bias[0]  /= (int32_t) packet_count;
00465     gyro_bias[1]  /= (int32_t) packet_count;
00466     gyro_bias[2]  /= (int32_t) packet_count;
00467     
00468   if(accel_bias[2] > 0L) {accel_bias[2] -= (int32_t) accelsensitivity;}  // Remove gravity from the z-axis accelerometer bias calculation
00469   else {accel_bias[2] += (int32_t) accelsensitivity;}
00470  
00471 // Construct the gyro biases for push to the hardware gyro bias registers, which are reset to zero upon device startup
00472   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
00473   data[1] = (-gyro_bias[0]/4)       & 0xFF; // Biases are additive, so change sign on calculated average gyro biases
00474   data[2] = (-gyro_bias[1]/4  >> 8) & 0xFF;
00475   data[3] = (-gyro_bias[1]/4)       & 0xFF;
00476   data[4] = (-gyro_bias[2]/4  >> 8) & 0xFF;
00477   data[5] = (-gyro_bias[2]/4)       & 0xFF;
00478 
00479 // Push gyro biases to hardware registers
00480   writeByte(MPU6050_ADDRESS, XG_OFFS_USRH, data[0]); 
00481   writeByte(MPU6050_ADDRESS, XG_OFFS_USRL, data[1]);
00482   writeByte(MPU6050_ADDRESS, YG_OFFS_USRH, data[2]);
00483   writeByte(MPU6050_ADDRESS, YG_OFFS_USRL, data[3]);
00484   writeByte(MPU6050_ADDRESS, ZG_OFFS_USRH, data[4]);
00485   writeByte(MPU6050_ADDRESS, ZG_OFFS_USRL, data[5]);
00486 
00487   dest1[0] = (float) gyro_bias[0]/(float) gyrosensitivity; // construct gyro bias in deg/s for later manual subtraction
00488   dest1[1] = (float) gyro_bias[1]/(float) gyrosensitivity;
00489   dest1[2] = (float) gyro_bias[2]/(float) gyrosensitivity;
00490 
00491 // Construct the accelerometer biases for push to the hardware accelerometer bias registers. These registers contain
00492 // factory trim values which must be added to the calculated accelerometer biases; on boot up these registers will hold
00493 // non-zero values. In addition, bit 0 of the lower byte must be preserved since it is used for temperature
00494 // compensation calculations. Accelerometer bias registers expect bias input as 2048 LSB per g, so that
00495 // the accelerometer biases calculated above must be divided by 8.
00496 
00497   int32_t accel_bias_reg[3] = {0, 0, 0}; // A place to hold the factory accelerometer trim biases
00498   readBytes(MPU6050_ADDRESS, XA_OFFSET_H, 2, &data[0]); // Read factory accelerometer trim values
00499   accel_bias_reg[0] = (int16_t) ((int16_t)data[0] << 8) | data[1];
00500   readBytes(MPU6050_ADDRESS, YA_OFFSET_H, 2, &data[0]);
00501   accel_bias_reg[1] = (int16_t) ((int16_t)data[0] << 8) | data[1];
00502   readBytes(MPU6050_ADDRESS, ZA_OFFSET_H, 2, &data[0]);
00503   accel_bias_reg[2] = (int16_t) ((int16_t)data[0] << 8) | data[1];
00504   
00505   uint32_t mask = 1uL; // Define mask for temperature compensation bit 0 of lower byte of accelerometer bias registers
00506   uint8_t mask_bit[3] = {0, 0, 0}; // Define array to hold mask bit for each accelerometer bias axis
00507   
00508   for(ii = 0; ii < 3; ii++) {
00509     if(accel_bias_reg[ii] & mask) mask_bit[ii] = 0x01; // If temperature compensation bit is set, record that fact in mask_bit
00510   }
00511 
00512   // Construct total accelerometer bias, including calculated average accelerometer bias from above
00513   accel_bias_reg[0] -= (accel_bias[0]/8); // Subtract calculated averaged accelerometer bias scaled to 2048 LSB/g (16 g full scale)
00514   accel_bias_reg[1] -= (accel_bias[1]/8);
00515   accel_bias_reg[2] -= (accel_bias[2]/8);
00516  
00517   data[0] = (accel_bias_reg[0] >> 8) & 0xFF;
00518   data[1] = (accel_bias_reg[0])      & 0xFF;
00519   data[1] = data[1] | mask_bit[0]; // preserve temperature compensation bit when writing back to accelerometer bias registers
00520   data[2] = (accel_bias_reg[1] >> 8) & 0xFF;
00521   data[3] = (accel_bias_reg[1])      & 0xFF;
00522   data[3] = data[3] | mask_bit[1]; // preserve temperature compensation bit when writing back to accelerometer bias registers
00523   data[4] = (accel_bias_reg[2] >> 8) & 0xFF;
00524   data[5] = (accel_bias_reg[2])      & 0xFF;
00525   data[5] = data[5] | mask_bit[2]; // preserve temperature compensation bit when writing back to accelerometer bias registers
00526 
00527   // Push accelerometer biases to hardware registers
00528 //  writeByte(MPU6050_ADDRESS, XA_OFFSET_H, data[0]);  
00529 //  writeByte(MPU6050_ADDRESS, XA_OFFSET_L_TC, data[1]);
00530 //  writeByte(MPU6050_ADDRESS, YA_OFFSET_H, data[2]);
00531 //  writeByte(MPU6050_ADDRESS, YA_OFFSET_L_TC, data[3]);  
00532 //  writeByte(MPU6050_ADDRESS, ZA_OFFSET_H, data[4]);
00533 //  writeByte(MPU6050_ADDRESS, ZA_OFFSET_L_TC, data[5]);
00534 
00535 // Output scaled accelerometer biases for manual subtraction in the main program
00536    dest2[0] = (float)accel_bias[0]/(float)accelsensitivity; 
00537    dest2[1] = (float)accel_bias[1]/(float)accelsensitivity;
00538    dest2[2] = (float)accel_bias[2]/(float)accelsensitivity;
00539 }
00540 
00541 
00542 // Accelerometer and gyroscope self test; check calibration wrt factory settings
00543 void MPU6050SelfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass
00544 {
00545    uint8_t rawData[4] = {0, 0, 0, 0};
00546    uint8_t selfTest[6];
00547    float factoryTrim[6];
00548    
00549    // Configure the accelerometer for self-test
00550    writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0xF0); // Enable self test on all three axes and set accelerometer range to +/- 8 g
00551    writeByte(MPU6050_ADDRESS, GYRO_CONFIG,  0xE0); // Enable self test on all three axes and set gyro range to +/- 250 degrees/s
00552    wait(0.25);  // Delay a while to let the device execute the self-test
00553    rawData[0] = readByte(MPU6050_ADDRESS, SELF_TEST_X); // X-axis self-test results
00554    rawData[1] = readByte(MPU6050_ADDRESS, SELF_TEST_Y); // Y-axis self-test results
00555    rawData[2] = readByte(MPU6050_ADDRESS, SELF_TEST_Z); // Z-axis self-test results
00556    rawData[3] = readByte(MPU6050_ADDRESS, SELF_TEST_A); // Mixed-axis self-test results
00557    // Extract the acceleration test results first
00558    selfTest[0] = (rawData[0] >> 3) | (rawData[3] & 0x30) >> 4 ; // XA_TEST result is a five-bit unsigned integer
00559    selfTest[1] = (rawData[1] >> 3) | (rawData[3] & 0x0C) >> 4 ; // YA_TEST result is a five-bit unsigned integer
00560    selfTest[2] = (rawData[2] >> 3) | (rawData[3] & 0x03) >> 4 ; // ZA_TEST result is a five-bit unsigned integer
00561    // Extract the gyration test results first
00562    selfTest[3] = rawData[0]  & 0x1F ; // XG_TEST result is a five-bit unsigned integer
00563    selfTest[4] = rawData[1]  & 0x1F ; // YG_TEST result is a five-bit unsigned integer
00564    selfTest[5] = rawData[2]  & 0x1F ; // ZG_TEST result is a five-bit unsigned integer   
00565    // Process results to allow final comparison with factory set values
00566    factoryTrim[0] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[0] - 1.0f)/30.0f))); // FT[Xa] factory trim calculation
00567    factoryTrim[1] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[1] - 1.0f)/30.0f))); // FT[Ya] factory trim calculation
00568    factoryTrim[2] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[2] - 1.0f)/30.0f))); // FT[Za] factory trim calculation
00569    factoryTrim[3] =  ( 25.0f*131.0f)*(pow( 1.046f , (selfTest[3] - 1.0f) ));             // FT[Xg] factory trim calculation
00570    factoryTrim[4] =  (-25.0f*131.0f)*(pow( 1.046f , (selfTest[4] - 1.0f) ));             // FT[Yg] factory trim calculation
00571    factoryTrim[5] =  ( 25.0f*131.0f)*(pow( 1.046f , (selfTest[5] - 1.0f) ));             // FT[Zg] factory trim calculation
00572    
00573  //  Output self-test results and factory trim calculation if desired
00574  //  Serial.println(selfTest[0]); Serial.println(selfTest[1]); Serial.println(selfTest[2]);
00575  //  Serial.println(selfTest[3]); Serial.println(selfTest[4]); Serial.println(selfTest[5]);
00576  //  Serial.println(factoryTrim[0]); Serial.println(factoryTrim[1]); Serial.println(factoryTrim[2]);
00577  //  Serial.println(factoryTrim[3]); Serial.println(factoryTrim[4]); Serial.println(factoryTrim[5]);
00578 
00579  // Report results as a ratio of (STR - FT)/FT; the change from Factory Trim of the Self-Test Response
00580  // To get to percent, must multiply by 100 and subtract result from 100
00581    for (int i = 0; i < 6; i++) {
00582      destination[i] = 100.0f + 100.0f*(selfTest[i] - factoryTrim[i])/factoryTrim[i]; // Report percent differences
00583    }
00584    
00585 }
00586 
00587 
00588 // Implementation of Sebastian Madgwick's "...efficient orientation filter for... inertial/magnetic sensor arrays"
00589 // which fuses acceleration and rotation rate to produce a quaternion-based estimate of relative
00590 // device orientation -- which can be converted to yaw, pitch, and roll. Useful for stabilizing quadcopters, etc.
00591 // The performance of the orientation filter is at least as good as conventional Kalman-based filtering algorithms
00592 // but is much less computationally intensive---it can be performed on a 3.3 V Pro Mini operating at 8 MHz!
00593         void MadgwickQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz)
00594         {
00595             float q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3];         // short name local variable for readability
00596             float norm;                                               // vector norm
00597             float f1, f2, f3;                                         // objective funcyion elements
00598             float J_11or24, J_12or23, J_13or22, J_14or21, J_32, J_33; // objective function Jacobian elements
00599             float qDot1, qDot2, qDot3, qDot4;
00600             float hatDot1, hatDot2, hatDot3, hatDot4;
00601             float gerrx, gerry, gerrz, gbiasx, gbiasy, gbiasz;  // gyro bias error
00602 
00603             // Auxiliary variables to avoid repeated arithmetic
00604             float _halfq1 = 0.5f * q1;
00605             float _halfq2 = 0.5f * q2;
00606             float _halfq3 = 0.5f * q3;
00607             float _halfq4 = 0.5f * q4;
00608             float _2q1 = 2.0f * q1;
00609             float _2q2 = 2.0f * q2;
00610             float _2q3 = 2.0f * q3;
00611             float _2q4 = 2.0f * q4;
00612 //            float _2q1q3 = 2.0f * q1 * q3;
00613 //            float _2q3q4 = 2.0f * q3 * q4;
00614 
00615             // Normalise accelerometer measurement
00616             norm = sqrt(ax * ax + ay * ay + az * az);
00617             if (norm == 0.0f) return; // handle NaN
00618             norm = 1.0f/norm;
00619             ax *= norm;
00620             ay *= norm;
00621             az *= norm;
00622             
00623             // Compute the objective function and Jacobian
00624             f1 = _2q2 * q4 - _2q1 * q3 - ax;
00625             f2 = _2q1 * q2 + _2q3 * q4 - ay;
00626             f3 = 1.0f - _2q2 * q2 - _2q3 * q3 - az;
00627             J_11or24 = _2q3;
00628             J_12or23 = _2q4;
00629             J_13or22 = _2q1;
00630             J_14or21 = _2q2;
00631             J_32 = 2.0f * J_14or21;
00632             J_33 = 2.0f * J_11or24;
00633           
00634             // Compute the gradient (matrix multiplication)
00635             hatDot1 = J_14or21 * f2 - J_11or24 * f1;
00636             hatDot2 = J_12or23 * f1 + J_13or22 * f2 - J_32 * f3;
00637             hatDot3 = J_12or23 * f2 - J_33 *f3 - J_13or22 * f1;
00638             hatDot4 = J_14or21 * f1 + J_11or24 * f2;
00639             
00640             // Normalize the gradient
00641             norm = sqrt(hatDot1 * hatDot1 + hatDot2 * hatDot2 + hatDot3 * hatDot3 + hatDot4 * hatDot4);
00642             hatDot1 /= norm;
00643             hatDot2 /= norm;
00644             hatDot3 /= norm;
00645             hatDot4 /= norm;
00646             
00647             // Compute estimated gyroscope biases
00648             gerrx = _2q1 * hatDot2 - _2q2 * hatDot1 - _2q3 * hatDot4 + _2q4 * hatDot3;
00649             gerry = _2q1 * hatDot3 + _2q2 * hatDot4 - _2q3 * hatDot1 - _2q4 * hatDot2;
00650             gerrz = _2q1 * hatDot4 - _2q2 * hatDot3 + _2q3 * hatDot2 - _2q4 * hatDot1;
00651             
00652             // Compute and remove gyroscope biases
00653             gbiasx += gerrx * deltat * zeta;
00654             gbiasy += gerry * deltat * zeta;
00655             gbiasz += gerrz * deltat * zeta;
00656  //           gx -= gbiasx;
00657  //           gy -= gbiasy;
00658  //           gz -= gbiasz;
00659             
00660             // Compute the quaternion derivative
00661             qDot1 = -_halfq2 * gx - _halfq3 * gy - _halfq4 * gz;
00662             qDot2 =  _halfq1 * gx + _halfq3 * gz - _halfq4 * gy;
00663             qDot3 =  _halfq1 * gy - _halfq2 * gz + _halfq4 * gx;
00664             qDot4 =  _halfq1 * gz + _halfq2 * gy - _halfq3 * gx;
00665 
00666             // Compute then integrate estimated quaternion derivative
00667             q1 += (qDot1 -(beta * hatDot1)) * deltat;
00668             q2 += (qDot2 -(beta * hatDot2)) * deltat;
00669             q3 += (qDot3 -(beta * hatDot3)) * deltat;
00670             q4 += (qDot4 -(beta * hatDot4)) * deltat;
00671 
00672             // Normalize the quaternion
00673             norm = sqrt(q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4);    // normalise quaternion
00674             norm = 1.0f/norm;
00675             q[0] = q1 * norm;
00676             q[1] = q2 * norm;
00677             q[2] = q3 * norm;
00678             q[3] = q4 * norm;
00679             
00680         }
00681         
00682   
00683   };
00684 #endif