MPU6050数据的读取[转载+整理]

arduino – MPU6050 新手学习笔记

1.MPU6050是什么？

MPU6050是一个6轴运动处理组件，包含了3轴加速度 和3轴陀螺仪。

2.加速度传感器是干嘛用的？

这个要结合图片来说明，大家可以看这里：
http://download.csdn.net/download/feixiangtiakongn/4545536
总而言这，加速度传感器，其实是力传感器。用来检查上下左右前后哪几个面都受了多少力（包括重力）

3.陀螺仪是干嘛用的？
简而言之，陀螺仪就是角速度检测仪。比如，一块板，以X轴为轴心，在一秒钟的时间转到了90度，那么它在X轴上的角速度就是 90度/秒  （DPS, 角速度单位，Degree Per Second的缩写°/S ，体现了转动的快慢）

4.MPU6050分辨率是多少？

3轴加速度 和3轴陀螺仪分别用了3个16位的ADC, 也就是说，加速度有3个16位ADC，其中每个轴使用了一个。也是说，每个轴输出的数据，是2^16 也就是 -32768 —- +32768。陀螺仪也是一样。

5. 单位换算
上面说的-32768 — +32768 ，那么这个数字到底代表了什么呢？比如陀螺仪 32768 到底是指角速度达到多少度/秒 ？
这个其实是根据MPU6050设置的量程来决定的，量程不一样，32768代表的值就不一样。

MPU6050的量程设置，在 MPU6050::initialize() （MPU6050.cpp库）初始化函数中进行了设置：
setFullScaleGyroRange(MPU6050_GYRO_FS_250);
setFullScaleAccelRange(MPU6050_ACCEL_FS_2);
分别设置为，250度/秒 , 2g

按陀螺仪来说，MPU6050 有四个量程可选：
±250，±500，±1000，±2000 度/s
比方说，设置了是 ±250 , 那么-32768  —- +32768 就代表了 -250 —- +250 。此时它的LSB(拉傻B，最低有效位) 是 131 LSB/(度/s)

 MPU 6050 读角度与单位换算

参考数据手册：PS-MPU-6000A
使用带有DMP的最新库函数（https://github.com/jrowberg/i2cdevlib），程序模板采用MPU6050_DMP6例程。

角度：
DMP库函数的dmpGetYawPitchRoll，可以得到pitch(俯仰），yaw(偏航），roll（滚转）角度。

角速度：
void getRotation(int16_t* x, int16_t* y, int16_t* z);
int16_t getRotationX();
int16_t getRotationY();
int16_t getRotationZ();
16位，配置时四个量程可选：±250，±500，±1000，±2000 度/s。
在dmp的例程中初始化：setFullScaleGyroRange(MPU6050_GYRO_FS_2000);
说明是选用最高量程±2000º/s，则换算系数=2^16/4000=16.4 LSB/(度/s)

加速度库函数：
void getAcceleration(int16_t* x, int16_t* y, int16_t* z);
int16_t getAccelerationX();
int16_t getAccelerationY();
int16_t getAccelerationZ();
16位，配置时四个量程可选：±2，±4，±8，±16 g。
在dmp的例程中没有找到初始化部分，估计是采用了缺省配置。
通过观察输出值，采用的是最小量程±2g，则换算系数=2^16/4=16384 LSB/g

下面是程序，中断方式，需要把MPU的中断接到arduino数字2脚上。

// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation // is used in I2Cdev.h #include "Wire.h" // I2Cdev and MPU6050 must be installed as libraries, or else the .cpp/.h files // for both classes must be in the include path of your project #include "I2Cdev.h" #include "MPU6050_6Axis_MotionApps20.h" MPU6050 mpu(0x68); // MPU control/status vars bool dmpReady = false; // set true if DMP init was successful uint8_t mpuIntStatus; // holds actual interrupt status byte from MPU uint8_t devStatus; // return status after each device operation (0 = success, !0 = error) uint16_t packetSize; // expected DMP packet size (default is 42 bytes) uint16_t fifoCount; // count of all bytes currently in FIFO uint8_t fifoBuffer[64]; // FIFO storage buffer // orientation/motion vars Quaternion q; // [w, x, y, z] quaternion container VectorFloat gravity; // [x, y, z] gravity vector float ypr[3]; // [yaw, pitch, roll] yaw/pitch/roll container and gravity vector // ================================================================ // === INTERRUPT DETECTION ROUTINE === // ================================================================ volatile bool mpuInterrupt = false; // indicates whether MPU interrupt pin has gone high void dmpDataReady() { mpuInterrupt = true; } // ================================================================ // === INITIAL SETUP === // ================================================================ void setup() { Serial.begin(115200); // opens serial port, sets data rate to 9600 bps // join I2C bus (I2Cdev library doesn't do this automatically) Wire.begin(); // initialize device Serial.println("Initializing I2C devices..."); mpu.initialize(); // verify connection Serial.println("Testing device connections..."); Serial.println(mpu.testConnection() ? "MPU6050 connection successful" : "MPU6050 connection failed"); delay(2); // load and configure the DMP Serial.println("Initializing DMP..."); devStatus = mpu.dmpInitialize(); // make sure it worked (returns 0 if so) if (devStatus == 0) { // turn on the DMP, now that it's ready Serial.println("Enabling DMP..."); mpu.setDMPEnabled(true); // enable Arduino interrupt detection Serial.println("Enabling interrupt detection (Arduino external interrupt 0)..."); attachInterrupt(0, dmpDataReady, RISING); mpuIntStatus = mpu.getIntStatus(); // set our DMP Ready flag so the main loop() function knows it's okay to use it Serial.println("DMP ready! Waiting for first interrupt..."); dmpReady = true; // get expected DMP packet size for later comparison packetSize = mpu.dmpGetFIFOPacketSize(); } else { // ERROR! // 1 = initial memory load failed // 2 = DMP configuration updates failed // (if it's going to break, usually the code will be 1) Serial.print("DMP Initialization failed (code "); Serial.print(devStatus); Serial.println(")"); } } void loop() { float alpha,omiga; // if programming failed, don't try to do anything if (!dmpReady) return; // wait for MPU interrupt or extra packet(s) available if (!mpuInterrupt && fifoCount < packetSize) return; // reset interrupt flag and get INT_STATUS byte mpuInterrupt = false; mpuIntStatus = mpu.getIntStatus(); // get current FIFO count fifoCount = mpu.getFIFOCount(); // check for overflow (this should never happen unless our code is too inefficient) if ((mpuIntStatus & 0x10) || fifoCount == 1024) { // reset so we can continue cleanly mpu.resetFIFO(); Serial.println("FIFO overflow!"); // otherwise, check for DMP data ready interrupt (this should happen frequently) } else if (mpuIntStatus & 0x02) { // wait for correct available data length, should be a VERY short wait while (fifoCount < packetSize) fifoCount = mpu.getFIFOCount(); // read a packet from FIFO mpu.getFIFOBytes(fifoBuffer, packetSize); // track FIFO count here in case there is > 1 packet available // (this lets us immediately read more without waiting for an interrupt) fifoCount -= packetSize; mpu.dmpGetQuaternion(&q, fifoBuffer); mpu.dmpGetGravity(&gravity, &q); mpu.dmpGetYawPitchRoll(ypr, &q, &gravity); //从DMP中取出Yaw、Pitch、Roll三个轴的角度，放入数组ypr。单位：弧度 alpha=-ypr[2] * 180/M_PI; omiga=mpu.getRotationX()/16.4; //配置是16位表示正负2000°/s, 65536/4000 Serial.print("Alpha "); Serial.print(alpha); Serial.print("\tOmiga "); Serial.println(omiga); } }

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// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation   // is used in I2Cdev.h   #include "Wire.h"     // I2Cdev and MPU6050 must be installed as libraries, or else the .cpp/.h files   // for both classes must be in the include path of your project   #include "I2Cdev.h"     #include "MPU6050_6Axis_MotionApps20.h"   MPU6050 mpu(0x68);     // MPU control/status vars   bool dmpReady = false;  // set true if DMP init was successful   uint8_t mpuIntStatus;   // holds actual interrupt status byte from MPU   uint8_t devStatus;      // return status after each device operation (0 = success, !0 = error)   uint16_t packetSize;    // expected DMP packet size (default is 42 bytes)   uint16_t fifoCount;     // count of all bytes currently in FIFO   uint8_t fifoBuffer[64]; // FIFO storage buffer     // orientation/motion vars   Quaternion q;           // [w, x, y, z]         quaternion container   VectorFloat gravity;    // [x, y, z]            gravity vector   float ypr[3];           // [yaw, pitch, roll]   yaw/pitch/roll container and gravity vector       // ================================================================   // ===               INTERRUPT DETECTION ROUTINE                ===   // ================================================================     volatile bool mpuInterrupt = false;     // indicates whether MPU interrupt pin has gone high   void dmpDataReady() {     mpuInterrupt = true;   }         // ================================================================   // ===                      INITIAL SETUP                       ===   // ================================================================     void setup() {     Serial.begin(115200);        // opens serial port, sets data rate to 9600 bps       // join I2C bus (I2Cdev library doesn't do this automatically)     Wire.begin();       // initialize device     Serial.println("Initializing I2C devices...");     mpu.initialize();       // verify connection     Serial.println("Testing device connections...");     Serial.println(mpu.testConnection() ? "MPU6050 connection successful" : "MPU6050 connection failed");       delay(2);       // load and configure the DMP     Serial.println("Initializing DMP...");     devStatus = mpu.dmpInitialize();       // make sure it worked (returns 0 if so)     if (devStatus == 0) {       // turn on the DMP, now that it's ready       Serial.println("Enabling DMP...");       mpu.setDMPEnabled(true);         // enable Arduino interrupt detection       Serial.println("Enabling interrupt detection (Arduino external interrupt 0)...");       attachInterrupt(0, dmpDataReady, RISING);       mpuIntStatus = mpu.getIntStatus();         // set our DMP Ready flag so the main loop() function knows it's okay to use it       Serial.println("DMP ready! Waiting for first interrupt...");       dmpReady = true;         // get expected DMP packet size for later comparison       packetSize = mpu.dmpGetFIFOPacketSize();     }     else {       // ERROR!       // 1 = initial memory load failed       // 2 = DMP configuration updates failed       // (if it's going to break, usually the code will be 1)       Serial.print("DMP Initialization failed (code ");       Serial.print(devStatus);       Serial.println(")");     }   }     void loop()   {     float alpha,omiga;       // if programming failed, don't try to do anything     if (!dmpReady)       return;       // wait for MPU interrupt or extra packet(s) available     if (!mpuInterrupt && fifoCount < packetSize)       return;       // reset interrupt flag and get INT_STATUS byte     mpuInterrupt = false;     mpuIntStatus = mpu.getIntStatus();       // get current FIFO count     fifoCount = mpu.getFIFOCount();       // check for overflow (this should never happen unless our code is too inefficient)     if ((mpuIntStatus & 0x10) || fifoCount == 1024) {       // reset so we can continue cleanly       mpu.resetFIFO();       Serial.println("FIFO overflow!");         // otherwise, check for DMP data ready interrupt (this should happen frequently)     }     else if (mpuIntStatus & 0x02) {       // wait for correct available data length, should be a VERY short wait       while (fifoCount < packetSize) fifoCount = mpu.getFIFOCount();         // read a packet from FIFO       mpu.getFIFOBytes(fifoBuffer, packetSize);         // track FIFO count here in case there is > 1 packet available       // (this lets us immediately read more without waiting for an interrupt)       fifoCount -= packetSize;         mpu.dmpGetQuaternion(&q, fifoBuffer);       mpu.dmpGetGravity(&gravity, &q);       mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);  //从DMP中取出Yaw、Pitch、Roll三个轴的角度，放入数组ypr。单位：弧度       alpha=-ypr[2] * 180/M_PI;         omiga=mpu.getRotationX()/16.4;        //配置是16位表示正负2000°/s, 65536/4000         Serial.print("Alpha ");       Serial.print(alpha);       Serial.print("\tOmiga ");       Serial.println(omiga);       }   }

****MPU6050库的安装方法*************************
1. 下载arduino编译器，目前版本为1.0.5。
2. 下载MPU6050库。进入“https://github.com/jrowberg/i2cdevlib”，点击“zip”即可。
3. 安装。将上一步下载的“I2Cdev”、“MPU6050”两个文件夹拷贝到“arduino-1.0.5\libraries”目录下。
运行arduino可以在例子中看到MPU6050。OK！