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MPU6050.cpp
00001 /* MPU6050 Library 00002 * 00003 * @author: Baser Kandehir 00004 * @date: July 16, 2015 00005 * @license: MIT license 00006 * 00007 * Copyright (c) 2015, Baser Kandehir, baser.kandehir@ieee.metu.edu.tr 00008 * 00009 * Permission is hereby granted, free of charge, to any person obtaining a copy 00010 * of this software and associated documentation files (the "Software"), to deal 00011 * in the Software without restriction, including without limitation the rights 00012 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 00013 * copies of the Software, and to permit persons to whom the Software is 00014 * furnished to do so, subject to the following conditions: 00015 * 00016 * The above copyright notice and this permission notice shall be included in 00017 * all copies or substantial portions of the Software. 00018 * 00019 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 00020 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 00021 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 00022 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 00023 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 00024 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 00025 * THE SOFTWARE. 00026 * 00027 */ 00028 00029 // Most of the code is adapted from Kris Winer's MPU6050 library 00030 00031 #include "MPU6050.h" 00032 00033 /* For LPC1768 board */ 00034 //I2C i2c(p9,p10); // setup i2c (SDA,SCL) 00035 00036 /* For NUCLEO-F411RE board */ 00037 static I2C i2c(PTE25,PTE24); // setup i2c (SDA,SCL) 00038 00039 /* Set initial input parameters */ 00040 00041 // Acc Full Scale Range +-2G 4G 8G 16G 00042 enum Ascale 00043 { 00044 AFS_2G=0, 00045 AFS_4G, 00046 AFS_8G, 00047 AFS_16G 00048 }; 00049 00050 // Gyro Full Scale Range +-250 500 1000 2000 Degrees per second 00051 enum Gscale 00052 { 00053 GFS_250DPS=0, 00054 GFS_500DPS, 00055 GFS_1000DPS, 00056 GFS_2000DPS 00057 }; 00058 00059 // Sensor datas 00060 float ax,ay,az; 00061 float gx,gy,gz; 00062 float axx; 00063 int16_t accelData[3],gyroData[3],tempData; 00064 float accelBias[3] = {0, 0, 0}; // Bias corrections for acc 00065 float gyroBias[3] = {0, 0, 0}; // Bias corrections for gyro 00066 00067 // Specify sensor full scale range 00068 int Ascale = AFS_2G; 00069 int Gscale = GFS_250DPS; 00070 00071 // Scale resolutions per LSB for the sensors 00072 float aRes, gRes; 00073 00074 // Calculates Acc resolution 00075 void MPU6050::getAres() 00076 { 00077 switch(Ascale) 00078 { 00079 case AFS_2G: 00080 aRes = 2.0/32768.0; 00081 break; 00082 case AFS_4G: 00083 aRes = 4.0/32768.0; 00084 break; 00085 case AFS_8G: 00086 aRes = 8.0/32768.0; 00087 break; 00088 case AFS_16G: 00089 aRes = 16.0/32768.0; 00090 break; 00091 } 00092 } 00093 00094 // Calculates Gyro resolution 00095 void MPU6050::getGres() 00096 { 00097 switch(Gscale) 00098 { 00099 case GFS_250DPS: 00100 gRes = 250.0/32768.0; 00101 break; 00102 case GFS_500DPS: 00103 gRes = 500.0/32768.0; 00104 break; 00105 case GFS_1000DPS: 00106 gRes = 1000.0/32768.0; 00107 break; 00108 case GFS_2000DPS: 00109 gRes = 2000.0/32768.0; 00110 break; 00111 } 00112 } 00113 00114 void MPU6050::writeByte(uint8_t address, uint8_t subAddress, uint8_t data) 00115 { 00116 char data_write[2]; 00117 data_write[0]=subAddress; // I2C sends MSB first. Namely >>|subAddress|>>|data| 00118 data_write[1]=data; 00119 i2c.write(address,data_write,2,0); // i2c.write(int address, char* data, int length, bool repeated=false); 00120 } 00121 00122 char MPU6050::readByte(uint8_t address, uint8_t subAddress) 00123 { 00124 char data_read[1]; // will store the register data 00125 char data_write[1]; 00126 data_write[0]=subAddress; 00127 i2c.write(address,data_write,1,1); // have not stopped yet 00128 i2c.read(address,data_read,1,0); // read the data and stop 00129 return data_read[0]; 00130 } 00131 00132 void MPU6050::readBytes(uint8_t address, uint8_t subAddress, uint8_t byteNum, uint8_t* dest) 00133 { 00134 char data[14],data_write[1]; 00135 data_write[0]=subAddress; 00136 i2c.write(address,data_write,1,1); 00137 i2c.read(address,data,byteNum,0); 00138 for(int i=0;i<byteNum;i++) // equate the addresses 00139 dest[i]=data[i]; 00140 } 00141 00142 // Communication test: CHECKADDRESS register reading 00143 void MPU6050::checkaddress() 00144 { 00145 uint8_t checkaddress = readByte(MPU6050_ADDRESS, CHECKADDRESS_MPU6050); // Should return 0x68 00146 pc.printf("Sensor Address ID: 0x%x \r\n",checkaddress); 00147 00148 if(checkaddress==0x68) 00149 { 00150 pc.printf("IMU is online now... \r\n"); 00151 } 00152 else 00153 { 00154 pc.printf("No connection to IMU !! Check the connections... \r\n"); 00155 } 00156 } 00157 00158 // Initializes MPU6050 with the following config: 00159 // PLL with X axis gyroscope reference 00160 // Sample rate: 200Hz for gyro and acc 00161 // Interrupts are disabled 00162 void MPU6050::init() 00163 { 00164 i2c.frequency(400000); // fast i2c: 400 kHz 00165 00166 /* Wake up the device */ 00167 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00); // wake up the device by clearing the sleep bit (bit6) 00168 wait_ms(100); // wait 100 ms to stabilize 00169 00170 /* Get stable time source */ 00171 // PLL with X axis gyroscope reference is used to improve stability 00172 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01); 00173 00174 /* Configure Gyroscope and Accelerometer */ 00175 // Disable FSYNC, acc bandwidth: 44 Hz, gyro bandwidth: 42 Hz 00176 // Sample rates: 1kHz, maximum delay: 4.9ms (which is pretty good for a 200 Hz maximum rate) 00177 writeByte(MPU6050_ADDRESS, CONFIG, 0x03); 00178 00179 /* Set sample rate = gyroscope output rate/(1+SMPLRT_DIV) */ 00180 // SMPLRT_DIV=4 and sample rate=200 Hz (compatible with config above) 00181 writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x04); 00182 00183 /* Accelerometer configuration */ 00184 uint8_t temp = readByte(MPU6050_ADDRESS, ACCEL_CONFIG); 00185 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, temp & ~0xE0); // Clear self-test bits [7:5] 00186 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, temp & ~0x18); // Clear AFS bits [4:3] 00187 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, temp | Ascale<<3); // Set full scale range 00188 00189 /* Gyroscope configuration */ 00190 temp = readByte(MPU6050_ADDRESS, GYRO_CONFIG); 00191 writeByte(MPU6050_ADDRESS, GYRO_CONFIG, temp & ~0xE0); // Clear self-test bits [7:5] 00192 writeByte(MPU6050_ADDRESS, GYRO_CONFIG, temp & ~0x18); // Clear FS bits [4:3] 00193 writeByte(MPU6050_ADDRESS, GYRO_CONFIG, temp | Gscale<<3); // Set full scale range 00194 } 00195 00196 // Resets the device 00197 void MPU6050::reset() 00198 { 00199 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // set bit7 to reset the device 00200 wait_ms(100); // wait 100 ms to stabilize 00201 } 00202 00203 void MPU6050::readAccelData(int16_t* dest) 00204 { 00205 uint8_t rawData[6]; // x,y,z acc data 00206 readBytes(MPU6050_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // read six raw data registers sequentially and write them into data array 00207 00208 /* Turn the MSB LSB into signed 16-bit value */ 00209 dest[0] = (int16_t)(((int16_t)rawData[0]<<8) | rawData[1]); // ACCEL_XOUT 00210 dest[1] = (int16_t)(((int16_t)rawData[2]<<8) | rawData[3]); // ACCEL_YOUT 00211 dest[2] = (int16_t)(((int16_t)rawData[4]<<8) | rawData[5]); // ACCEL_ZOUT 00212 } 00213 00214 void MPU6050::readGyroData(int16_t* dest) 00215 { 00216 uint8_t rawData[6]; // x,y,z gyro data 00217 readBytes(MPU6050_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // read the six raw data registers sequentially and write them into data array 00218 00219 /* Turn the MSB LSB into signed 16-bit value */ 00220 dest[0] = (int16_t)(((int16_t)rawData[0]<<8) | rawData[1]); // GYRO_XOUT 00221 dest[1] = (int16_t)(((int16_t)rawData[2]<<8) | rawData[3]); // GYRO_YOUT 00222 dest[2] = (int16_t)(((int16_t)rawData[4]<<8) | rawData[5]); // GYRO_ZOUT 00223 } 00224 00225 int16_t MPU6050::readTempData() 00226 { 00227 uint8_t rawData[2]; // temperature data 00228 readBytes(MPU6050_ADDRESS, TEMP_OUT_H, 2, &rawData[0]); // read the two raw data registers sequentially and write them into data array 00229 return (int16_t)(((int16_t)rawData[0]<<8) | rawData[1]); // turn the MSB LSB into signed 16-bit value 00230 } 00231 00232 /* Function which accumulates gyro and accelerometer data after device initialization. 00233 It calculates the average of the at-rest readings and 00234 then loads the resulting offsets into accelerometer and gyro bias registers. */ 00235 /* 00236 IMPORTANT NOTE: In this function; 00237 Resulting accel offsets are NOT pushed to the accel bias registers. accelBias[i] offsets are used in the main program. 00238 Resulting gyro offsets are pushed to the gyro bias registers. gyroBias[i] offsets are NOT used in the main program. 00239 Resulting data seems satisfactory. 00240 */ 00241 // dest1: accelBias dest2: gyroBias 00242 void MPU6050::calibrate(float* dest1, float* dest2) 00243 { 00244 uint8_t data[12]; // data array to hold acc and gyro x,y,z data 00245 uint16_t fifo_count, packet_count, count; 00246 int32_t accel_bias[3] = {0,0,0}; 00247 int32_t gyro_bias[3] = {0,0,0}; 00248 float aRes = 2.0/32768.0; 00249 float gRes = 250.0/32768.0; 00250 uint16_t accelsensitivity = 16384; // = 1/aRes = 16384 LSB/g 00251 //uint16_t gyrosensitivity = 131; // = 1/gRes = 131 LSB/dps 00252 00253 reset(); // Reset device 00254 00255 /* Get stable time source */ 00256 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01); // PLL with X axis gyroscope reference is used to improve stability 00257 writeByte(MPU6050_ADDRESS, PWR_MGMT_2, 0x00); // Disable accel only low power mode 00258 wait(0.2); 00259 00260 /* Configure device for bias calculation */ 00261 writeByte(MPU6050_ADDRESS, INT_ENABLE, 0x00); // Disable all interrupts 00262 writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00); // Disable FIFO 00263 writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00); // Turn on internal clock source 00264 writeByte(MPU6050_ADDRESS, I2C_MST_CTRL, 0x00); // Disable I2C master 00265 writeByte(MPU6050_ADDRESS, USER_CTRL, 0x00); // Disable FIFO and I2C master modes 00266 writeByte(MPU6050_ADDRESS, USER_CTRL, 0x04); // Reset FIFO 00267 wait(0.015); 00268 00269 /* Configure accel and gyro for bias calculation */ 00270 writeByte(MPU6050_ADDRESS, CONFIG, 0x01); // Set low-pass filter to 188 Hz 00271 writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x00); // Set sample rate to 1 kHz 00272 writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity 00273 writeByte(MPU6050_ADDRESS, GYRO_CONFIG, 0x00); // Set gyro full-scale to 250 degrees per second, maximum sensitivity 00274 00275 /* Configure FIFO to capture accelerometer and gyro data for bias calculation */ 00276 writeByte(MPU6050_ADDRESS, USER_CTRL, 0x40); // Enable FIFO 00277 writeByte(MPU6050_ADDRESS, FIFO_EN, 0x78); // Enable accelerometer and gyro for FIFO (max size 1024 bytes in MPU-6050) 00278 wait(0.08); // Sample rate is 1 kHz, accumulates 80 samples in 80 milliseconds. 00279 // accX: 2 byte, accY: 2 byte, accZ: 2 byte. gyroX: 2 byte, gyroY: 2 byte, gyroZ: 2 byte. 12*80=960 byte < 1024 byte 00280 00281 /* At end of sample accumulation, turn off FIFO sensor read */ 00282 writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00); // Disable FIFO 00283 readBytes(MPU6050_ADDRESS, FIFO_COUNTH, 2, &data[0]); // Read FIFO sample count 00284 fifo_count = ((uint16_t)data[0] << 8) | data[1]; 00285 packet_count = fifo_count/12; // The number of sets of full acc and gyro data for averaging. packet_count = 80 in this case 00286 00287 for(count=0; count<packet_count; count++) 00288 { 00289 int16_t accel_temp[3]={0,0,0}; 00290 int16_t gyro_temp[3]={0,0,0}; 00291 readBytes(MPU6050_ADDRESS, FIFO_R_W, 12, &data[0]); // read data for averaging 00292 00293 /* Form signed 16-bit integer for each sample in FIFO */ 00294 accel_temp[0] = (int16_t) (((int16_t)data[0] << 8) | data[1] ) ; 00295 accel_temp[1] = (int16_t) (((int16_t)data[2] << 8) | data[3] ) ; 00296 accel_temp[2] = (int16_t) (((int16_t)data[4] << 8) | data[5] ) ; 00297 gyro_temp[0] = (int16_t) (((int16_t)data[6] << 8) | data[7] ) ; 00298 gyro_temp[1] = (int16_t) (((int16_t)data[8] << 8) | data[9] ) ; 00299 gyro_temp[2] = (int16_t) (((int16_t)data[10] << 8) | data[11]) ; 00300 00301 /* Sum individual signed 16-bit biases to get accumulated signed 32-bit biases */ 00302 accel_bias[0] += (int32_t) accel_temp[0]; 00303 accel_bias[1] += (int32_t) accel_temp[1]; 00304 accel_bias[2] += (int32_t) accel_temp[2]; 00305 gyro_bias[0] += (int32_t) gyro_temp[0]; 00306 gyro_bias[1] += (int32_t) gyro_temp[1]; 00307 gyro_bias[2] += (int32_t) gyro_temp[2]; 00308 } 00309 00310 /* Normalize sums to get average count biases */ 00311 accel_bias[0] /= (int32_t) packet_count; 00312 accel_bias[1] /= (int32_t) packet_count; 00313 accel_bias[2] /= (int32_t) packet_count; 00314 gyro_bias[0] /= (int32_t) packet_count; 00315 gyro_bias[1] /= (int32_t) packet_count; 00316 gyro_bias[2] /= (int32_t) packet_count; 00317 00318 /* Remove gravity from the z-axis accelerometer bias calculation */ 00319 if(accel_bias[2] > 0) {accel_bias[2] -= (int32_t) accelsensitivity;} 00320 else {accel_bias[2] += (int32_t) accelsensitivity;} 00321 00322 /* Output scaled accelerometer biases for manual subtraction in the main program */ 00323 dest1[0] = accel_bias[0]*aRes; 00324 dest1[1] = accel_bias[1]*aRes; 00325 dest1[2] = accel_bias[2]*aRes; 00326 00327 /* Construct the gyro biases for push to the hardware gyro bias registers, which are reset to zero upon device startup */ 00328 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 00329 data[1] = (-gyro_bias[0]/4) & 0xFF; // Biases are additive, so change sign on calculated average gyro biases 00330 data[2] = (-gyro_bias[1]/4 >> 8) & 0xFF; 00331 data[3] = (-gyro_bias[1]/4) & 0xFF; 00332 data[4] = (-gyro_bias[2]/4 >> 8) & 0xFF; 00333 data[5] = (-gyro_bias[2]/4) & 0xFF; 00334 00335 /* Push gyro biases to hardware registers */ 00336 writeByte(MPU6050_ADDRESS, XG_OFFS_USRH, data[0]); 00337 writeByte(MPU6050_ADDRESS, XG_OFFS_USRL, data[1]); 00338 writeByte(MPU6050_ADDRESS, YG_OFFS_USRH, data[2]); 00339 writeByte(MPU6050_ADDRESS, YG_OFFS_USRL, data[3]); 00340 writeByte(MPU6050_ADDRESS, ZG_OFFS_USRH, data[4]); 00341 writeByte(MPU6050_ADDRESS, ZG_OFFS_USRL, data[5]); 00342 00343 /* Construct gyro bias in deg/s for later manual subtraction */ 00344 dest2[0] = gyro_bias[0]*gRes; 00345 dest2[1] = gyro_bias[1]*gRes; 00346 dest2[2] = gyro_bias[2]*gRes; 00347 } 00348 00349 void MPU6050::complementaryFilter(float* pitch, float* roll) 00350 { 00351 /* Get actual acc value */ 00352 readAccelData(accelData); 00353 getAres(); 00354 ax = accelData[0]*aRes - accelBias[0]; 00355 ay = accelData[1]*aRes - accelBias[1]; 00356 az = accelData[2]*aRes - accelBias[2]; 00357 00358 axx = 9.80665f * ax; 00359 00360 /* Get actual gyro value */ 00361 readGyroData(gyroData); 00362 getGres(); 00363 gx = gyroData[0]*gRes; // - gyroBias[0]; // Results are better without extracting gyroBias[i] 00364 gy = gyroData[1]*gRes; // - gyroBias[1]; 00365 gz = gyroData[2]*gRes; // - gyroBias[2]; 00366 00367 float pitchAcc, rollAcc; 00368 00369 /* Integrate the gyro data(deg/s) over time to get angle */ 00370 *pitch += gx * dt; // Angle around the X-axis 00371 *roll -= gy * dt; // Angle around the Y-axis 00372 00373 /* Turning around the X-axis results in a vector on the Y-axis 00374 whereas turning around the Y-axis results in a vector on the X-axis. */ 00375 pitchAcc = atan2f(accelData[1], accelData[2])*180/PI; 00376 rollAcc = atan2f(accelData[0], accelData[2])*180/PI; 00377 00378 /* Apply Complementary Filter */ 00379 *pitch = *pitch * 0.98 + pitchAcc * 0.02; 00380 *roll = *roll * 0.98 + rollAcc * 0.02; 00381 }
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