MPU6050.cpp

00001 //This file is an adaptation of Kris Winer's MPU6050 library and example code
00002 //See: https://developer.mbed.org/users/onehorse/code/MPU6050IMU/
00003 //Specifically see https://developer.mbed.org/users/onehorse/code/MPU6050IMU/file/e0381ca0edac/main.cpp for license information :)
00004 
00005 #include "MPU6050.h"
00006 #include "mbed.h"
00007 #include "math.h"
00008  
00009 
00010 
00011 // Specify sensor full scale
00012 int Gscale = GFS_250DPS;
00013 int Ascale = AFS_8G;
00014 
00015 //Set up I2C, (SDA,SCL)
00016 I2C MPU_i2c(PB_9, PB_8);
00017 
00018 //DigitalOut myled(LED1);
00019    
00020 float aRes, gRes; // scale resolutions per LSB for the sensors
00021   
00022 // Pin definitions
00023 int intPin = 12;  // These can be changed, 2 and 3 are the Arduinos ext int pins
00024 
00025 int16_t accelCount[3];  // Stores the 16-bit signed accelerometer sensor output
00026 float ax, ay, az;       // Stores the real accel value in g's
00027 int16_t gyroCount[3];   // Stores the 16-bit signed gyro sensor output
00028 float gx, gy, gz;       // Stores the real gyro value in degrees per seconds
00029 float gyroBias[3] = {0, 0, 0}, accelBias[3] = {0, 0, 0}; // Bias corrections for gyro and accelerometer
00030 int16_t tempCount;   // Stores the real internal chip temperature in degrees Celsius
00031 float temperature;
00032 float SelfTest[6];
00033 
00034 //int delt_t = 0; // used to control display output rate
00035 //int count = 0;  // used to control display output rate
00036 float sum = 0;
00037 uint32_t sumCount = 0;
00038 
00039 // parameters for 6 DoF sensor fusion calculations
00040 float PI = 3.14159265358979323846f;
00041 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
00042 float beta = sqrt(3.0f / 4.0f) * GyroMeasError;  // compute beta
00043 float GyroMeasDrift = PI * (1.0f / 180.0f);      // gyroscope measurement drift in rad/s/s (start at 0.0 deg/s/s)
00044 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
00045 float pitch, yaw, roll;
00046 float deltat = 0.0f;                              // integration interval for both filter schemes
00047 int lastUpdate = 0, firstUpdate = 0, Now = 0;     // used to calculate integration interval                               // used to calculate integration interval
00048 float q[4] = {1.0f, 0.0f, 0.0f, 0.0f};            // vector to hold quaternion
00049 
00050 
00051     void MPU6050::writeByte(uint8_t address, uint8_t subAddress, uint8_t data)
00052 {
00053    char data_write[2];
00054    data_write[0] = subAddress;
00055    data_write[1] = data;
00056    __disable_irq();
00057    MPU_i2c.write(address, data_write, 2, 0);
00058    __enable_irq();
00059 }
00060 
00061     char MPU6050::readByte(uint8_t address, uint8_t subAddress)
00062 {
00063     char data[1]; // `data` will store the register data     
00064     char data_write[1];
00065     data_write[0] = subAddress;
00066      __disable_irq();
00067     MPU_i2c.write(address, data_write, 1, 1); // no stop
00068     MPU_i2c.read(address, data, 1, 0); 
00069     __enable_irq();
00070     return data[0]; 
00071 }
00072 
00073     void MPU6050::readBytes(uint8_t address, uint8_t subAddress, uint8_t count, uint8_t * dest)
00074 {     
00075     char data[14];
00076     char data_write[1];
00077     data_write[0] = subAddress;
00078      __disable_irq();
00079     MPU_i2c.write(address, data_write, 1, 1); // no stop
00080     MPU_i2c.read(address, data, count, 0); 
00081     __enable_irq();
00082     for(int ii = 0; ii < count; ii++) {
00083      dest[ii] = data[ii];
00084     }
00085 } 
00086  
00087 
00088 void MPU6050::getGres() {
00089   switch (Gscale)
00090   {
00091     // Possible gyro scales (and their register bit settings) are:
00092     // 250 DPS (00), 500 DPS (01), 1000 DPS (10), and 2000 DPS  (11). 
00093         // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value:
00094     case GFS_250DPS:
00095           gRes = 250.0/32768.0;
00096           break;
00097     case GFS_500DPS:
00098           gRes = 500.0/32768.0;
00099           break;
00100     case GFS_1000DPS:
00101           gRes = 1000.0/32768.0;
00102           break;
00103     case GFS_2000DPS:
00104           gRes = 2000.0/32768.0;
00105           break;
00106   }
00107 }
00108 
00109 void MPU6050::getAres() {
00110   switch (Ascale)
00111   {
00112     // Possible accelerometer scales (and their register bit settings) are:
00113     // 2 Gs (00), 4 Gs (01), 8 Gs (10), and 16 Gs  (11). 
00114         // Here's a bit of an algorith to calculate DPS/(ADC tick) based on that 2-bit value:
00115     case AFS_2G:
00116           aRes = 2.0/32768.0;
00117           break;
00118     case AFS_4G:
00119           aRes = 4.0/32768.0;
00120           break;
00121     case AFS_8G:
00122           aRes = 8.0/32768.0;
00123           break;
00124     case AFS_16G:
00125           aRes = 16.0/32768.0;
00126           break;
00127   }
00128 }
00129 
00130 
00131 void MPU6050::readAccelData(int16_t * destination)
00132 {
00133   uint8_t rawData[6];  // x/y/z accel register data stored here
00134   readBytes(MPU6050_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]);  // Read the six raw data registers into data array
00135   destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ;  // Turn the MSB and LSB into a signed 16-bit value
00136   destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;  
00137   destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 
00138 }
00139 
00140 void MPU6050::readGyroData(int16_t * destination)
00141 {
00142   uint8_t rawData[6];  // x/y/z gyro register data stored here
00143   readBytes(MPU6050_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]);  // Read the six raw data registers sequentially into data array
00144   destination[0] = (int16_t)(((int16_t)rawData[0] << 8) | rawData[1]) ;  // Turn the MSB and LSB into a signed 16-bit value
00145   destination[1] = (int16_t)(((int16_t)rawData[2] << 8) | rawData[3]) ;  
00146   destination[2] = (int16_t)(((int16_t)rawData[4] << 8) | rawData[5]) ; 
00147 }
00148 
00149 int16_t MPU6050::readTempData()
00150 {
00151   uint8_t rawData[2];  // x/y/z gyro register data stored here
00152   readBytes(MPU6050_ADDRESS, TEMP_OUT_H, 2, &rawData[0]);  // Read the two raw data registers sequentially into data array 
00153   return (int16_t)(((int16_t)rawData[0]) << 8 | rawData[1]) ;  // Turn the MSB and LSB into a 16-bit value
00154 }
00155 
00156 
00157 
00158 // Configure the motion detection control for low power accelerometer mode
00159 void MPU6050::LowPowerAccelOnly()
00160 {
00161 
00162 // The sensor has a high-pass filter necessary to invoke to allow the sensor motion detection algorithms work properly
00163 // Motion detection occurs on free-fall (acceleration below a threshold for some time for all axes), motion (acceleration
00164 // above a threshold for some time on at least one axis), and zero-motion toggle (acceleration on each axis less than a 
00165 // threshold for some time sets this flag, motion above the threshold turns it off). The high-pass filter takes gravity out
00166 // consideration for these threshold evaluations; otherwise, the flags would be set all the time!
00167   
00168   uint8_t c = readByte(MPU6050_ADDRESS, PWR_MGMT_1);
00169   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c & ~0x30); // Clear sleep and cycle bits [5:6]
00170   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c |  0x30); // Set sleep and cycle bits [5:6] to zero to make sure accelerometer is running
00171 
00172   c = readByte(MPU6050_ADDRESS, PWR_MGMT_2);
00173   writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c & ~0x38); // Clear standby XA, YA, and ZA bits [3:5]
00174   writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c |  0x00); // Set XA, YA, and ZA bits [3:5] to zero to make sure accelerometer is running
00175     
00176   c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
00177   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x07); // Clear high-pass filter bits [2:0]
00178 // 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
00179   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG,  c | 0x00);  // Set ACCEL_HPF to 0; reset mode disbaling high-pass filter
00180 
00181   c = readByte(MPU6050_ADDRESS, CONFIG);
00182   writeByte(MPU6050_ADDRESS, CONFIG, c & ~0x07); // Clear low-pass filter bits [2:0]
00183   writeByte(MPU6050_ADDRESS, CONFIG, c |  0x00);  // Set DLPD_CFG to 0; 260 Hz bandwidth, 1 kHz rate
00184     
00185   c = readByte(MPU6050_ADDRESS, INT_ENABLE);
00186   writeByte(MPU6050_ADDRESS, INT_ENABLE, c & ~0xFF);  // Clear all interrupts
00187   writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x40);  // Enable motion threshold (bits 5) interrupt only
00188   
00189 // Motion detection interrupt requires the absolute value of any axis to lie above the detection threshold
00190 // for at least the counter duration
00191   writeByte(MPU6050_ADDRESS, MOT_THR, 0x80); // Set motion detection to 0.256 g; LSB = 2 mg
00192   writeByte(MPU6050_ADDRESS, MOT_DUR, 0x01); // Set motion detect duration to 1  ms; LSB is 1 ms @ 1 kHz rate
00193   
00194   wait(0.1);  // Add delay for accumulation of samples
00195   
00196   c = readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
00197   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x07); // Clear high-pass filter bits [2:0]
00198   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c |  0x07);  // Set ACCEL_HPF to 7; hold the initial accleration value as a referance
00199    
00200   c = readByte(MPU6050_ADDRESS, PWR_MGMT_2);
00201   writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c & ~0xC7); // Clear standby XA, YA, and ZA bits [3:5] and LP_WAKE_CTRL bits [6:7]
00202   writeByte(MPU6050_ADDRESS, PWR_MGMT_2, c |  0x47); // Set wakeup frequency to 5 Hz, and disable XG, YG, and ZG gyros (bits [0:2])  
00203 
00204   c = readByte(MPU6050_ADDRESS, PWR_MGMT_1);
00205   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c & ~0x20); // Clear sleep and cycle bit 5
00206   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, c |  0x20); // Set cycle bit 5 to begin low power accelerometer motion interrupts
00207 
00208 }
00209 
00210 
00211 void MPU6050::resetMPU6050() {
00212   // reset device
00213   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
00214   wait(0.1);
00215   }
00216   
00217   
00218 void MPU6050::initMPU6050()
00219 {  
00220  // Initialize MPU6050 device
00221  // wake up device
00222   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00); // Clear sleep mode bit (6), enable all sensors 
00223   wait(0.1); // Delay 100 ms for PLL to get established on x-axis gyro; should check for PLL ready interrupt  
00224 
00225  // get stable time source
00226   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01);  // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001
00227 
00228  // Configure Gyro and Accelerometer
00229  // Disable FSYNC and set accelerometer and gyro bandwidth to 44 and 42 Hz, respectively; 
00230  // DLPF_CFG = bits 2:0 = 010; this sets the sample rate at 1 kHz for both
00231  // Maximum delay is 4.9 ms which is just over a 200 Hz maximum rate
00232   writeByte(MPU6050_ADDRESS, CONFIG, 0x03);  
00233  
00234  // Set sample rate = gyroscope output rate/(1 + SMPLRT_DIV)
00235   writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x04);  // Use a 200 Hz rate; the same rate set in CONFIG above
00236  
00237  // Set gyroscope full scale range
00238  // Range selects FS_SEL and AFS_SEL are 0 - 3, so 2-bit values are left-shifted into positions 4:3
00239   uint8_t c =  readByte(MPU6050_ADDRESS, GYRO_CONFIG);
00240   writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] 
00241   writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
00242   writeByte(MPU6050_ADDRESS, GYRO_CONFIG, c | Gscale << 3); // Set full scale range for the gyro
00243    
00244  // Set accelerometer configuration
00245   c =  readByte(MPU6050_ADDRESS, ACCEL_CONFIG);
00246   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0xE0); // Clear self-test bits [7:5] 
00247   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c & ~0x18); // Clear AFS bits [4:3]
00248   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, c | Ascale << 3); // Set full scale range for the accelerometer 
00249 
00250   // Configure Interrupts and Bypass Enable
00251   // Set interrupt pin active high, push-pull, and clear on read of INT_STATUS, enable I2C_BYPASS_EN so additional chips 
00252   // can join the I2C bus and all can be controlled by the Arduino as master
00253    writeByte(MPU6050_ADDRESS, INT_PIN_CFG, 0x22);    
00254    writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x01);  // Enable data ready (bit 0) interrupt
00255 }
00256 
00257 // Function which accumulates gyro and accelerometer data after device initialization. It calculates the average
00258 // of the at-rest readings and then loads the resulting offsets into accelerometer and gyro bias registers.
00259 void MPU6050::calibrateMPU6050(float * dest1, float * dest2)
00260 {  
00261   uint8_t data[12]; // data array to hold accelerometer and gyro x, y, z, data
00262   uint16_t ii, packet_count, fifo_count;
00263   int32_t gyro_bias[3] = {0, 0, 0}, accel_bias[3] = {0, 0, 0};
00264   
00265 // reset device, reset all registers, clear gyro and accelerometer bias registers
00266   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // Write a one to bit 7 reset bit; toggle reset device
00267   wait(0.1);  
00268    
00269 // get stable time source
00270 // Set clock source to be PLL with x-axis gyroscope reference, bits 2:0 = 001
00271   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01);  
00272   writeByte(MPU6050_ADDRESS, PWR_MGMT_2, 0x00); 
00273   wait(0.2);
00274   
00275 // Configure device for bias calculation
00276   writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x00);   // Disable all interrupts
00277   writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00);      // Disable FIFO
00278   writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00);   // Turn on internal clock source
00279   writeByte(MPU6050_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master
00280   writeByte(MPU6050_ADDRESS, USER_CTRL, 0x00);    // Disable FIFO and I2C master modes
00281   writeByte(MPU6050_ADDRESS, USER_CTRL, 0x0C);    // Reset FIFO and DMP
00282   wait(0.015);
00283   
00284 // Configure MPU6050 gyro and accelerometer for bias calculation
00285   writeByte(MPU6050_ADDRESS, CONFIG, 0x01);      // Set low-pass filter to 188 Hz
00286   writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x00);  // Set sample rate to 1 kHz
00287   writeByte(MPU6050_ADDRESS, GYRO_CONFIG, 0x00);  // Set gyro full-scale to 250 degrees per second, maximum sensitivity
00288   writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity
00289  
00290   uint16_t  gyrosensitivity  = 131;   // = 131 LSB/degrees/sec
00291   uint16_t  accelsensitivity = 16384;  // = 16384 LSB/g
00292 
00293 // Configure FIFO to capture accelerometer and gyro data for bias calculation
00294   writeByte(MPU6050_ADDRESS, USER_CTRL, 0x40);   // Enable FIFO  
00295   writeByte(MPU6050_ADDRESS, FIFO_EN, 0x78);     // Enable gyro and accelerometer sensors for FIFO  (max size 1024 bytes in MPU-6050)
00296   wait(0.08); // accumulate 80 samples in 80 milliseconds = 960 bytes
00297 
00298 // At end of sample accumulation, turn off FIFO sensor read
00299   writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00);        // Disable gyro and accelerometer sensors for FIFO
00300   readBytes(MPU6050_ADDRESS, FIFO_COUNTH, 2, &data[0]); // read FIFO sample count
00301   fifo_count = ((uint16_t)data[0] << 8) | data[1];
00302   packet_count = fifo_count/12;// How many sets of full gyro and accelerometer data for averaging
00303 
00304   for (ii = 0; ii < packet_count; ii++) {
00305     int16_t accel_temp[3] = {0, 0, 0}, gyro_temp[3] = {0, 0, 0};
00306     readBytes(MPU6050_ADDRESS, FIFO_R_W, 12, &data[0]); // read data for averaging
00307     accel_temp[0] = (int16_t) (((int16_t)data[0] << 8) | data[1]  ) ;  // Form signed 16-bit integer for each sample in FIFO
00308     accel_temp[1] = (int16_t) (((int16_t)data[2] << 8) | data[3]  ) ;
00309     accel_temp[2] = (int16_t) (((int16_t)data[4] << 8) | data[5]  ) ;    
00310     gyro_temp[0]  = (int16_t) (((int16_t)data[6] << 8) | data[7]  ) ;
00311     gyro_temp[1]  = (int16_t) (((int16_t)data[8] << 8) | data[9]  ) ;
00312     gyro_temp[2]  = (int16_t) (((int16_t)data[10] << 8) | data[11]) ;
00313     
00314     accel_bias[0] += (int32_t) accel_temp[0]; // Sum individual signed 16-bit biases to get accumulated signed 32-bit biases
00315     accel_bias[1] += (int32_t) accel_temp[1];
00316     accel_bias[2] += (int32_t) accel_temp[2];
00317     gyro_bias[0]  += (int32_t) gyro_temp[0];
00318     gyro_bias[1]  += (int32_t) gyro_temp[1];
00319     gyro_bias[2]  += (int32_t) gyro_temp[2];
00320             
00321 }
00322     accel_bias[0] /= (int32_t) packet_count; // Normalize sums to get average count biases
00323     accel_bias[1] /= (int32_t) packet_count;
00324     accel_bias[2] /= (int32_t) packet_count;
00325     gyro_bias[0]  /= (int32_t) packet_count;
00326     gyro_bias[1]  /= (int32_t) packet_count;
00327     gyro_bias[2]  /= (int32_t) packet_count;
00328     
00329   if(accel_bias[2] > 0L) {accel_bias[2] -= (int32_t) accelsensitivity;}  // Remove gravity from the z-axis accelerometer bias calculation
00330   else {accel_bias[2] += (int32_t) accelsensitivity;}
00331  
00332 // Construct the gyro biases for push to the hardware gyro bias registers, which are reset to zero upon device startup
00333   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
00334   data[1] = (-gyro_bias[0]/4)       & 0xFF; // Biases are additive, so change sign on calculated average gyro biases
00335   data[2] = (-gyro_bias[1]/4  >> 8) & 0xFF;
00336   data[3] = (-gyro_bias[1]/4)       & 0xFF;
00337   data[4] = (-gyro_bias[2]/4  >> 8) & 0xFF;
00338   data[5] = (-gyro_bias[2]/4)       & 0xFF;
00339 
00340 // Push gyro biases to hardware registers
00341   writeByte(MPU6050_ADDRESS, XG_OFFS_USRH, data[0]); 
00342   writeByte(MPU6050_ADDRESS, XG_OFFS_USRL, data[1]);
00343   writeByte(MPU6050_ADDRESS, YG_OFFS_USRH, data[2]);
00344   writeByte(MPU6050_ADDRESS, YG_OFFS_USRL, data[3]);
00345   writeByte(MPU6050_ADDRESS, ZG_OFFS_USRH, data[4]);
00346   writeByte(MPU6050_ADDRESS, ZG_OFFS_USRL, data[5]);
00347 
00348   dest1[0] = (float) gyro_bias[0]/(float) gyrosensitivity; // construct gyro bias in deg/s for later manual subtraction
00349   dest1[1] = (float) gyro_bias[1]/(float) gyrosensitivity;
00350   dest1[2] = (float) gyro_bias[2]/(float) gyrosensitivity;
00351 
00352 // Construct the accelerometer biases for push to the hardware accelerometer bias registers. These registers contain
00353 // factory trim values which must be added to the calculated accelerometer biases; on boot up these registers will hold
00354 // non-zero values. In addition, bit 0 of the lower byte must be preserved since it is used for temperature
00355 // compensation calculations. Accelerometer bias registers expect bias input as 2048 LSB per g, so that
00356 // the accelerometer biases calculated above must be divided by 8.
00357 
00358   int32_t accel_bias_reg[3] = {0, 0, 0}; // A place to hold the factory accelerometer trim biases
00359   readBytes(MPU6050_ADDRESS, XA_OFFSET_H, 2, &data[0]); // Read factory accelerometer trim values
00360   accel_bias_reg[0] = (int16_t) ((int16_t)data[0] << 8) | data[1];
00361   readBytes(MPU6050_ADDRESS, YA_OFFSET_H, 2, &data[0]);
00362   accel_bias_reg[1] = (int16_t) ((int16_t)data[0] << 8) | data[1];
00363   readBytes(MPU6050_ADDRESS, ZA_OFFSET_H, 2, &data[0]);
00364   accel_bias_reg[2] = (int16_t) ((int16_t)data[0] << 8) | data[1];
00365   
00366   uint32_t mask = 1uL; // Define mask for temperature compensation bit 0 of lower byte of accelerometer bias registers
00367   uint8_t mask_bit[3] = {0, 0, 0}; // Define array to hold mask bit for each accelerometer bias axis
00368   
00369   for(ii = 0; ii < 3; ii++) {
00370     if(accel_bias_reg[ii] & mask) mask_bit[ii] = 0x01; // If temperature compensation bit is set, record that fact in mask_bit
00371   }
00372 
00373   // Construct total accelerometer bias, including calculated average accelerometer bias from above
00374   accel_bias_reg[0] -= (accel_bias[0]/8); // Subtract calculated averaged accelerometer bias scaled to 2048 LSB/g (16 g full scale)
00375   accel_bias_reg[1] -= (accel_bias[1]/8);
00376   accel_bias_reg[2] -= (accel_bias[2]/8);
00377  
00378   data[0] = (accel_bias_reg[0] >> 8) & 0xFF;
00379   data[1] = (accel_bias_reg[0])      & 0xFF;
00380   data[1] = data[1] | mask_bit[0]; // preserve temperature compensation bit when writing back to accelerometer bias registers
00381   data[2] = (accel_bias_reg[1] >> 8) & 0xFF;
00382   data[3] = (accel_bias_reg[1])      & 0xFF;
00383   data[3] = data[3] | mask_bit[1]; // preserve temperature compensation bit when writing back to accelerometer bias registers
00384   data[4] = (accel_bias_reg[2] >> 8) & 0xFF;
00385   data[5] = (accel_bias_reg[2])      & 0xFF;
00386   data[5] = data[5] | mask_bit[2]; // preserve temperature compensation bit when writing back to accelerometer bias registers
00387 
00388   // Push accelerometer biases to hardware registers
00389 //  writeByte(MPU6050_ADDRESS, XA_OFFSET_H, data[0]);  
00390 //  writeByte(MPU6050_ADDRESS, XA_OFFSET_L_TC, data[1]);
00391 //  writeByte(MPU6050_ADDRESS, YA_OFFSET_H, data[2]);
00392 //  writeByte(MPU6050_ADDRESS, YA_OFFSET_L_TC, data[3]);  
00393 //  writeByte(MPU6050_ADDRESS, ZA_OFFSET_H, data[4]);
00394 //  writeByte(MPU6050_ADDRESS, ZA_OFFSET_L_TC, data[5]);
00395 
00396 // Output scaled accelerometer biases for manual subtraction in the main program
00397    dest2[0] = (float)accel_bias[0]/(float)accelsensitivity; 
00398    dest2[1] = (float)accel_bias[1]/(float)accelsensitivity;
00399    dest2[2] = (float)accel_bias[2]/(float)accelsensitivity;
00400 }
00401 
00402 
00403 // Accelerometer and gyroscope self test; check calibration wrt factory settings
00404 void MPU6050::MPU6050SelfTest(float * destination) // Should return percent deviation from factory trim values, +/- 14 or less deviation is a pass
00405 {
00406    uint8_t rawData[4] = {0, 0, 0, 0};
00407    uint8_t selfTest[6];
00408    float factoryTrim[6];
00409    
00410    // Configure the accelerometer for self-test
00411    writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0xF0); // Enable self test on all three axes and set accelerometer range to +/- 8 g
00412    writeByte(MPU6050_ADDRESS, GYRO_CONFIG,  0xE0); // Enable self test on all three axes and set gyro range to +/- 250 degrees/s
00413    wait(0.25);  // Delay a while to let the device execute the self-test
00414    rawData[0] = readByte(MPU6050_ADDRESS, SELF_TEST_X); // X-axis self-test results
00415    rawData[1] = readByte(MPU6050_ADDRESS, SELF_TEST_Y); // Y-axis self-test results
00416    rawData[2] = readByte(MPU6050_ADDRESS, SELF_TEST_Z); // Z-axis self-test results
00417    rawData[3] = readByte(MPU6050_ADDRESS, SELF_TEST_A); // Mixed-axis self-test results
00418    // Extract the acceleration test results first
00419    selfTest[0] = (rawData[0] >> 3) | (rawData[3] & 0x30) >> 4 ; // XA_TEST result is a five-bit unsigned integer
00420    selfTest[1] = (rawData[1] >> 3) | (rawData[3] & 0x0C) >> 4 ; // YA_TEST result is a five-bit unsigned integer
00421    selfTest[2] = (rawData[2] >> 3) | (rawData[3] & 0x03) >> 4 ; // ZA_TEST result is a five-bit unsigned integer
00422    // Extract the gyration test results first
00423    selfTest[3] = rawData[0]  & 0x1F ; // XG_TEST result is a five-bit unsigned integer
00424    selfTest[4] = rawData[1]  & 0x1F ; // YG_TEST result is a five-bit unsigned integer
00425    selfTest[5] = rawData[2]  & 0x1F ; // ZG_TEST result is a five-bit unsigned integer   
00426    // Process results to allow final comparison with factory set values
00427    factoryTrim[0] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[0] - 1.0f)/30.0f))); // FT[Xa] factory trim calculation
00428    factoryTrim[1] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[1] - 1.0f)/30.0f))); // FT[Ya] factory trim calculation
00429    factoryTrim[2] = (4096.0f*0.34f)*(pow( (0.92f/0.34f) , ((selfTest[2] - 1.0f)/30.0f))); // FT[Za] factory trim calculation
00430    factoryTrim[3] =  ( 25.0f*131.0f)*(pow( 1.046f , (selfTest[3] - 1.0f) ));             // FT[Xg] factory trim calculation
00431    factoryTrim[4] =  (-25.0f*131.0f)*(pow( 1.046f , (selfTest[4] - 1.0f) ));             // FT[Yg] factory trim calculation
00432    factoryTrim[5] =  ( 25.0f*131.0f)*(pow( 1.046f , (selfTest[5] - 1.0f) ));             // FT[Zg] factory trim calculation
00433    
00434  //  Output self-test results and factory trim calculation if desired
00435  //  Serial.println(selfTest[0]); Serial.println(selfTest[1]); Serial.println(selfTest[2]);
00436  //  Serial.println(selfTest[3]); Serial.println(selfTest[4]); Serial.println(selfTest[5]);
00437  //  Serial.println(factoryTrim[0]); Serial.println(factoryTrim[1]); Serial.println(factoryTrim[2]);
00438  //  Serial.println(factoryTrim[3]); Serial.println(factoryTrim[4]); Serial.println(factoryTrim[5]);
00439 
00440  // Report results as a ratio of (STR - FT)/FT; the change from Factory Trim of the Self-Test Response
00441  // To get to percent, must multiply by 100 and subtract result from 100
00442    for (int i = 0; i < 6; i++) {
00443      destination[i] = 100.0f + 100.0f*(selfTest[i] - factoryTrim[i])/factoryTrim[i]; // Report percent differences
00444    }
00445    
00446 }
00447 
00448 
00449 // Implementation of Sebastian Madgwick's "...efficient orientation filter for... inertial/magnetic sensor arrays"
00450 // (see http://www.x-io.co.uk/category/open-source/ for examples and more details)
00451 // which fuses acceleration and rotation rate to produce a quaternion-based estimate of relative
00452 // device orientation -- which can be converted to yaw, pitch, and roll. Useful for stabilizing quadcopters, etc.
00453 // The performance of the orientation filter is at least as good as conventional Kalman-based filtering algorithms
00454 // but is much less computationally intensive---it can be performed on a 3.3 V Pro Mini operating at 8 MHz!
00455         void MPU6050::MadgwickQuaternionUpdate(float ax, float ay, float az, float gx, float gy, float gz)
00456         {
00457             float q1 = q[0], q2 = q[1], q3 = q[2], q4 = q[3];         // short name local variable for readability
00458             float norm;                                               // vector norm
00459             float f1, f2, f3;                                         // objective funcyion elements
00460             float J_11or24, J_12or23, J_13or22, J_14or21, J_32, J_33; // objective function Jacobian elements
00461             float qDot1, qDot2, qDot3, qDot4;
00462             float hatDot1, hatDot2, hatDot3, hatDot4;
00463             float gerrx, gerry, gerrz, gbiasx, gbiasy, gbiasz;  // gyro bias error
00464 
00465             // Auxiliary variables to avoid repeated arithmetic
00466             float _halfq1 = 0.5f * q1;
00467             float _halfq2 = 0.5f * q2;
00468             float _halfq3 = 0.5f * q3;
00469             float _halfq4 = 0.5f * q4;
00470             float _2q1 = 2.0f * q1;
00471             float _2q2 = 2.0f * q2;
00472             float _2q3 = 2.0f * q3;
00473             float _2q4 = 2.0f * q4;
00474 //            float _2q1q3 = 2.0f * q1 * q3;
00475 //            float _2q3q4 = 2.0f * q3 * q4;
00476 
00477             // Normalise accelerometer measurement
00478             norm = sqrt(ax * ax + ay * ay + az * az);
00479             if (norm == 0.0f) return; // handle NaN (INF ?)
00480             norm = 1.0f/norm;
00481             ax *= norm;
00482             ay *= norm;
00483             az *= norm;
00484             
00485             // Compute the objective function and Jacobian
00486             f1 = _2q2 * q4 - _2q1 * q3 - ax;
00487             f2 = _2q1 * q2 + _2q3 * q4 - ay;
00488             f3 = 1.0f - _2q2 * q2 - _2q3 * q3 - az;
00489             J_11or24 = _2q3;
00490             J_12or23 = _2q4;
00491             J_13or22 = _2q1;
00492             J_14or21 = _2q2;
00493             J_32 = 2.0f * J_14or21;
00494             J_33 = 2.0f * J_11or24;
00495           
00496             // Compute the gradient (matrix multiplication)
00497             hatDot1 = J_14or21 * f2 - J_11or24 * f1;
00498             hatDot2 = J_12or23 * f1 + J_13or22 * f2 - J_32 * f3;
00499             hatDot3 = J_12or23 * f2 - J_33 *f3 - J_13or22 * f1;
00500             hatDot4 = J_14or21 * f1 + J_11or24 * f2;
00501             
00502             // Normalize the gradient
00503             norm = sqrt(hatDot1 * hatDot1 + hatDot2 * hatDot2 + hatDot3 * hatDot3 + hatDot4 * hatDot4);
00504             if (norm == 0.0f) return; // handle NaN (INF ?)
00505             hatDot1 /= norm;
00506             hatDot2 /= norm;
00507             hatDot3 /= norm;
00508             hatDot4 /= norm;
00509             
00510             // Compute estimated gyroscope biases
00511             gerrx = _2q1 * hatDot2 - _2q2 * hatDot1 - _2q3 * hatDot4 + _2q4 * hatDot3;
00512             gerry = _2q1 * hatDot3 + _2q2 * hatDot4 - _2q3 * hatDot1 - _2q4 * hatDot2;
00513             gerrz = _2q1 * hatDot4 - _2q2 * hatDot3 + _2q3 * hatDot2 - _2q4 * hatDot1;
00514             
00515             // Compute and remove gyroscope biases
00516             gbiasx += gerrx * deltat * zeta;
00517             gbiasy += gerry * deltat * zeta;
00518             gbiasz += gerrz * deltat * zeta;
00519  //           gx -= gbiasx;
00520  //           gy -= gbiasy;
00521  //           gz -= gbiasz;
00522             
00523             // Compute the quaternion derivative
00524             qDot1 = -_halfq2 * gx - _halfq3 * gy - _halfq4 * gz;
00525             qDot2 =  _halfq1 * gx + _halfq3 * gz - _halfq4 * gy;
00526             qDot3 =  _halfq1 * gy - _halfq2 * gz + _halfq4 * gx;
00527             qDot4 =  _halfq1 * gz + _halfq2 * gy - _halfq3 * gx;
00528 
00529             // Compute then integrate estimated quaternion derivative
00530             q1 += (qDot1 -(beta * hatDot1)) * deltat;
00531             q2 += (qDot2 -(beta * hatDot2)) * deltat;
00532             q3 += (qDot3 -(beta * hatDot3)) * deltat;
00533             q4 += (qDot4 -(beta * hatDot4)) * deltat;
00534 
00535             // Normalize the quaternion
00536             norm = sqrt(q1 * q1 + q2 * q2 + q3 * q3 + q4 * q4);    // normalise quaternion
00537             if (norm == 0.0f) return; // handle NaN (INF ?)
00538             norm = 1.0f/norm;
00539             q[0] = q1 * norm;
00540             q[1] = q2 * norm;
00541             q[2] = q3 * norm;
00542             q[3] = q4 * norm;
00543             
00544         }
00545         
00546 bool MPU6050::motion_sensor_init()
00547 {
00548 
00549     
00550 // Read the WHO_AM_I register, this is a good test of communication
00551     uint8_t whoami = readByte(MPU6050_ADDRESS, WHO_AM_I_MPU6050);  // Read WHO_AM_I register for MPU-6050
00552     //serial.printf("I AM 0x%x\n\r", whoami);
00553     //serial.printf("I SHOULD BE 0x68\n\r");
00554 
00555     if (whoami == 0x68) { // WHO_AM_I should always be 0x68
00556        // serial.printf("MPU6050 is online...");
00557         wait(1);
00558 
00559 
00560         MPU6050SelfTest(SelfTest); // Start by performing self test and reporting values
00561 /*
00562         serial.printf("x-axis self test: acceleration trim within : ");
00563         serial.printf("%f", SelfTest[0]);
00564         serial.printf("% of factory value \n\r");
00565         serial.printf("y-axis self test: acceleration trim within : ");
00566         serial.printf("%f", SelfTest[1]);
00567         serial.printf("% of factory value \n\r");
00568         serial.printf("z-axis self test: acceleration trim within : ");
00569         serial.printf("%f", SelfTest[2]);
00570         serial.printf("% of factory value \n\r");
00571         serial.printf("x-axis self test: gyration trim within : ");
00572         serial.printf("%f", SelfTest[3]);
00573         serial.printf("% of factory value \n\r");
00574         serial.printf("y-axis self test: gyration trim within : ");
00575         serial.printf("%f", SelfTest[4]);
00576         serial.printf("% of factory value \n\r");
00577         serial.printf("z-axis self test: gyration trim within : ");
00578         serial.printf("%f", SelfTest[5]);
00579         serial.printf("% of factory value \n\r");
00580 */
00581         wait(1);
00582 
00583         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) {
00584             resetMPU6050(); // Reset registers to default in preparation for device calibration
00585             initMPU6050();
00586             //serial.printf("MPU6050 initialized for active data mode....\n\r"); // Initialize device for active mode read of acclerometer, gyroscope, and temperature
00587 
00588             return TRUE;
00589         } else {
00590             //serial.printf("Device did not the pass self-test!\n\r");
00591             return FALSE;
00592 
00593         }
00594     } else {
00595         //serial.printf("Could not connect to MPU6050: \n\r");
00596         //serial.printf("%#x \n",  whoami);
00597 
00598         return FALSE;
00599     }
00600 
00601 
00602 }
00603 
00604 bool MPU6050::motion_update_data(MPU_data_type *new_data, int current_time_us)
00605 {
00606     if(readByte(MPU6050_ADDRESS, INT_STATUS) & 0x01) {
00607         readAccelData(accelCount);  // Read the x/y/z adc values
00608         getAres();
00609 
00610         // Now we'll calculate the accleration value into actual g's
00611         ax = (float)accelCount[0]*aRes - accelBias[0];  // get actual g value, this depends on scale being set
00612         ay = (float)accelCount[1]*aRes - accelBias[1];
00613         az = (float)accelCount[2]*aRes - accelBias[2];
00614 
00615         readGyroData(gyroCount);  // Read the x/y/z adc values
00616         getGres();
00617 
00618         // Calculate the gyro value into actual degrees per second
00619         gx = (float)gyroCount[0]*gRes; // - gyroBias[0];  // get actual gyro value, this depends on scale being set
00620         gy = (float)gyroCount[1]*gRes; // - gyroBias[1];
00621         gz = (float)gyroCount[2]*gRes; // - gyroBias[2];
00622 
00623         tempCount = readTempData();  // Read the x/y/z adc values
00624         temperature = (tempCount) / 340. + 36.53; // Temperature in degrees Centigrade
00625 
00626 
00627         Now = current_time_us;
00628         deltat = (float)((Now - lastUpdate)/1000000.0f) ; // set integration time by time elapsed since last filter update
00629         lastUpdate = Now;
00630 
00631         sum += deltat;
00632         sumCount++;
00633 
00634         if(lastUpdate - firstUpdate > 10000000.0f) {
00635             beta = 0.04;  // decrease filter gain after stabilized
00636             zeta = 0.015; // increase bias drift gain after stabilized
00637         }
00638 
00639         // Pass gyro rate as rad/s
00640         MadgwickQuaternionUpdate(ax, ay, az, gx*PI/180.0f, gy*PI/180.0f, gz*PI/180.0f);
00641 
00642 
00643 
00644 
00645         // Define output variables from updated quaternion---these are Tait-Bryan angles, commonly used in aircraft orientation.
00646         // In this coordinate system, the positive z-axis is down toward Earth.
00647         // 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.
00648         // Pitch is angle between sensor x-axis and Earth ground plane, toward the Earth is positive, up toward the sky is negative.
00649         // Roll is angle between sensor y-axis and Earth ground plane, y-axis up is positive roll.
00650         // These arise from the definition of the homogeneous rotation matrix constructed from quaternions.
00651         // Tait-Bryan angles as well as Euler angles are non-commutative; that is, the get the correct orientation the rotations must be
00652         // applied in the correct order which for this configuration is yaw, pitch, and then roll.
00653         // For more see http://en.wikipedia.org/wiki/Conversion_between_quaternions_and_Euler_angles which has additional links.
00654         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]);
00655         pitch = -asin(2.0f * (q[1] * q[3] - q[0] * q[2]));
00656         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]);
00657         pitch *= 180.0f / PI;
00658         yaw   *= 180.0f / PI;
00659         roll  *= 180.0f / PI;
00660 /*
00661         new_data->ax = (int) (ax / 16384.0f);
00662         new_data->ay = (int) (ay / 16384.0f);
00663         new_data->az = (int) (az / 16384.0f);
00664         new_data->yaw = (int) (yaw / 16384.0f);
00665         new_data->pitch = (int) (pitch / 16384.0f);
00666         new_data->roll = (int) (roll / 16384.0f);
00667 */
00668         new_data->ax = (int) (ax * 1000);
00669         new_data->ay = (int) (ay * 1000);
00670         new_data->az = (int) (az * 1000);
00671         new_data->yaw = (int) (yaw * 10);
00672         new_data->pitch = (int) (pitch * 10);
00673         new_data->roll = (int) (roll * 10);
00674         return TRUE;
00675 
00676     } else {
00677         return FALSE;
00678     }
00679 
00680 }
00681         
00682 void MPU6050_set_I2C_freq(int i2c_frequency)
00683 {
00684     MPU_i2c.frequency(i2c_frequency); 
00685 }
00686 
00687 
00688      
00689