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Diff: MPU6050.cpp
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diff -r 000000000000 -r 954f15bd95f1 MPU6050.cpp --- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/MPU6050.cpp Thu Jul 09 12:13:56 2015 +0000 @@ -0,0 +1,319 @@ +/* @author: Baser Kandehir +* @date: July 9, 2015 +* @license: Use this code however you'd like +*/ + +// Most of the code is adapted from Kris Winer's MPU6050 library + +#include "MPU6050.h" + +I2C i2c(p9,p10); // setup i2c (SDA,SCL) + +/* Set initial input parameters */ + +// Acc Full Scale Range +-2G 4G 8G 16G +enum Ascale +{ + AFS_2G=0, + AFS_4G, + AFS_8G, + AFS_16G +}; + +// Gyro Full Scale Range +-250 500 1000 2000 Degrees per second +enum Gscale +{ + GFS_250DPS=0, + GFS_500DPS, + GFS_1000DPS, + GFS_2000DPS +}; + +// Sensor datas +float ax,ay,az; +float gx,gy,gz; +int16_t accelData[3],gyroData[3],tempData; +float accelBias[3] = {0, 0, 0}; // Bias corrections for acc +float gyroBias[3] = {0, 0, 0}; // Bias corrections for gyro + +// Specify sensor full scale range +int Ascale = AFS_2G; +int Gscale = GFS_250DPS; + +// Scale resolutions per LSB for the sensors +float aRes, gRes; + +// Calculates Acc resolution +void MPU6050::getAres() +{ + switch(Ascale) + { + 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; + } +} + +// Calculates Gyro resolution +void MPU6050::getGres() +{ + switch(Gscale) + { + 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 MPU6050::writeByte(uint8_t address, uint8_t subAddress, uint8_t data) +{ + char data_write[2]; + data_write[0]=subAddress; // I2C sends MSB first. Namely >>|subAddress|>>|data| + data_write[1]=data; + i2c.write(address,data_write,2,0); // i2c.write(int address, char* data, int length, bool repeated=false); +} + +char MPU6050::readByte(uint8_t address, uint8_t subAddress) +{ + char data_read[1]; // will store the register data + char data_write[1]; + data_write[0]=subAddress; + i2c.write(address,data_write,1,1); // have not stopped yet + i2c.read(address,data_read,1,0); // read the data and stop + return data_read[0]; +} + +void MPU6050::readBytes(uint8_t address, uint8_t subAddress, uint8_t byteNum, uint8_t* dest) +{ + char data[14],data_write[1]; + data_write[0]=subAddress; + i2c.write(address,data_write,1,1); + i2c.read(address,data,byteNum,0); + for(int i=0;i<byteNum;i++) // equate the addresses + dest[i]=data[i]; +} + +// Communication test: WHO_AM_I register reading +void MPU6050::whoAmI() +{ + uint8_t whoAmI = readByte(MPU6050_ADDRESS, WHO_AM_I_MPU6050); // Should return 0x68 + ftdi.printf("I AM 0x%x \r\n",whoAmI); + + if(whoAmI==0x68) + { + ftdi.printf("MPU6050 is online... \r\n"); + led2=1; + } + else + { + ftdi.printf("Could not connect to MPU6050 \r\nCheck the connections... \r\n"); + toggler1.attach(&toggle_led1,0.1); // toggles led1 every 100 ms + } +} + +// Initializes MPU6050 with the following config: +// PLL with X axis gyroscope reference +// Sample rate: 200Hz for gyro and acc +// Interrupts are disabled +void MPU6050::init() +{ + /* Wake up the device */ + writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x00); // wake up the device by clearing the sleep bit (bit6) + wait_ms(100); // wait 100 ms to stabilize + + /* Get stable time source */ + // PLL with X axis gyroscope reference is used to improve stability + writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01); + + /* Configure Gyroscope and Accelerometer */ + // Disable FSYNC, acc bandwidth: 44 Hz, gyro bandwidth: 42 Hz + // Sample rates: 1kHz, maximum delay: 4.9ms (which is pretty good for a 200 Hz maximum rate) + writeByte(MPU6050_ADDRESS, CONFIG, 0x03); + + /* Set sample rate = gyroscope output rate/(1+SMPLRT_DIV) */ + // SMPLRT_DIV=4 and sample rate=200 Hz (compatible with config above) + writeByte(MPU6050_ADDRESS, SMPLRT_DIV, 0x04); + + /* Accelerometer configuration */ + uint8_t temp = readByte(MPU6050_ADDRESS, ACCEL_CONFIG); + writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, temp & ~0xE0); // Clear self-test bits [7:5] + writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, temp & ~0x18); // Clear AFS bits [4:3] + writeByte(MPU6050_ADDRESS, ACCEL_CONFIG, temp | Ascale<<3); // Set full scale range + + /* Gyroscope configuration */ + temp = readByte(MPU6050_ADDRESS, GYRO_CONFIG); + writeByte(MPU6050_ADDRESS, GYRO_CONFIG, temp & ~0xE0); // Clear self-test bits [7:5] + writeByte(MPU6050_ADDRESS, GYRO_CONFIG, temp & ~0x18); // Clear FS bits [4:3] + writeByte(MPU6050_ADDRESS, GYRO_CONFIG, temp | Gscale<<3); // Set full scale range +} + +// Resets the device +void MPU6050::reset() +{ + writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x80); // set bit7 to reset the device + wait_ms(100); // wait 100 ms to stabilize +} + +void MPU6050::readAccelData(int16_t* dest) +{ + uint8_t rawData[6]; // x,y,z acc data + readBytes(MPU6050_ADDRESS, ACCEL_XOUT_H, 6, &rawData[0]); // read six raw data registers sequentially and write them into data array + + /* Turn the MSB LSB into signed 16-bit value */ + dest[0] = (int16_t)(((int16_t)rawData[0]<<8) | rawData[1]); // ACCEL_XOUT + dest[1] = (int16_t)(((int16_t)rawData[2]<<8) | rawData[3]); // ACCEL_YOUT + dest[2] = (int16_t)(((int16_t)rawData[4]<<8) | rawData[5]); // ACCEL_ZOUT +} + +void MPU6050::readGyroData(int16_t* dest) +{ + uint8_t rawData[6]; // x,y,z gyro data + readBytes(MPU6050_ADDRESS, GYRO_XOUT_H, 6, &rawData[0]); // read the six raw data registers sequentially and write them into data array + + /* Turn the MSB LSB into signed 16-bit value */ + dest[0] = (int16_t)(((int16_t)rawData[0]<<8) | rawData[1]); // GYRO_XOUT + dest[1] = (int16_t)(((int16_t)rawData[2]<<8) | rawData[3]); // GYRO_YOUT + dest[2] = (int16_t)(((int16_t)rawData[4]<<8) | rawData[5]); // GYRO_ZOUT +} + +int16_t MPU6050::readTempData() +{ + uint8_t rawData[2]; // temperature data + readBytes(MPU6050_ADDRESS, TEMP_OUT_H, 2, &rawData[0]); // read the two raw data registers sequentially and write them into data array + return (int16_t)(((int16_t)rawData[0]<<8) | rawData[1]); // turn the MSB LSB into signed 16-bit value +} + +/* 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. */ +/* + IMPORTANT NOTE: In this function; + Resulting accel offsets are NOT pushed to the accel bias registers. accelBias[i] offsets are used in the main program. + Resulting gyro offsets are pushed to the gyro bias registers. gyroBias[i] offsets are NOT used in the main program. + Resulting data seems satisfactory. +*/ +// dest1: accelBias dest2: gyroBias +void MPU6050::calibrate(float* dest1, float* dest2) +{ + uint8_t data[12]; // data array to hold acc and gyro x,y,z data + uint16_t fifo_count, packet_count, count; + int32_t accel_bias[3] = {0,0,0}; + int32_t gyro_bias[3] = {0,0,0}; + float aRes = 2.0/32768.0; + float gRes = 250.0/32768.0; + uint16_t accelsensitivity = 16384; // = 1/aRes = 16384 LSB/g + //uint16_t gyrosensitivity = 131; // = 1/gRes = 131 LSB/dps + + reset(); // Reset device + + /* Get stable time source */ + writeByte(MPU6050_ADDRESS, PWR_MGMT_1, 0x01); // PLL with X axis gyroscope reference is used to improve stability + writeByte(MPU6050_ADDRESS, PWR_MGMT_2, 0x00); // Disable accel only low power mode + 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, 0x04); // Reset FIFO + wait(0.015); + + /* Configure accel and gyro 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, ACCEL_CONFIG, 0x00); // Set accelerometer full-scale to 2 g, maximum sensitivity + writeByte(MPU6050_ADDRESS, GYRO_CONFIG, 0x00); // Set gyro full-scale to 250 degrees per second, maximum sensitivity + + /* 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 accelerometer and gyro for FIFO (max size 1024 bytes in MPU-6050) + wait(0.08); // Sample rate is 1 kHz, accumulates 80 samples in 80 milliseconds. + // accX: 2 byte, accY: 2 byte, accZ: 2 byte. gyroX: 2 byte, gyroY: 2 byte, gyroZ: 2 byte. 12*80=960 byte < 1024 byte + + /* At end of sample accumulation, turn off FIFO sensor read */ + writeByte(MPU6050_ADDRESS, FIFO_EN, 0x00); // Disable FIFO + readBytes(MPU6050_ADDRESS, FIFO_COUNTH, 2, &data[0]); // Read FIFO sample count + fifo_count = ((uint16_t)data[0] << 8) | data[1]; + packet_count = fifo_count/12; // The number of sets of full acc and gyro data for averaging. packet_count = 80 in this case + + for(count=0; count<packet_count; count++) + { + int16_t accel_temp[3]={0,0,0}; + int16_t gyro_temp[3]={0,0,0}; + readBytes(MPU6050_ADDRESS, FIFO_R_W, 12, &data[0]); // read data for averaging + + /* Form signed 16-bit integer for each sample in FIFO */ + accel_temp[0] = (int16_t) (((int16_t)data[0] << 8) | data[1] ) ; + accel_temp[1] = (int16_t) (((int16_t)data[2] << 8) | data[3] ) ; + accel_temp[2] = (int16_t) (((int16_t)data[4] << 8) | data[5] ) ; + gyro_temp[0] = (int16_t) (((int16_t)data[6] << 8) | data[7] ) ; + gyro_temp[1] = (int16_t) (((int16_t)data[8] << 8) | data[9] ) ; + gyro_temp[2] = (int16_t) (((int16_t)data[10] << 8) | data[11]) ; + + /* Sum individual signed 16-bit biases to get accumulated signed 32-bit biases */ + accel_bias[0] += (int32_t) accel_temp[0]; + accel_bias[1] += (int32_t) accel_temp[1]; + accel_bias[2] += (int32_t) accel_temp[2]; + gyro_bias[0] += (int32_t) gyro_temp[0]; + gyro_bias[1] += (int32_t) gyro_temp[1]; + gyro_bias[2] += (int32_t) gyro_temp[2]; + } + + /* Normalize sums to get average count biases */ + accel_bias[0] /= (int32_t) packet_count; + accel_bias[1] /= (int32_t) packet_count; + accel_bias[2] /= (int32_t) packet_count; + gyro_bias[0] /= (int32_t) packet_count; + gyro_bias[1] /= (int32_t) packet_count; + gyro_bias[2] /= (int32_t) packet_count; + + /* Remove gravity from the z-axis accelerometer bias calculation */ + if(accel_bias[2] > 0) {accel_bias[2] -= (int32_t) accelsensitivity;} + else {accel_bias[2] += (int32_t) accelsensitivity;} + + /* Output scaled accelerometer biases for manual subtraction in the main program */ + dest1[0] = accel_bias[0]*aRes; + dest1[1] = accel_bias[1]*aRes; + dest1[2] = accel_bias[2]*aRes; + + /* 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]); + 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]); + + /* Construct gyro bias in deg/s for later manual subtraction */ + dest2[0] = gyro_bias[0]*gRes; + dest2[1] = gyro_bias[1]*gRes; + dest2[2] = gyro_bias[2]*gRes; +}