25. Chapter Attitude Sensor MPU6050

In this chapter, we will learn about a MPU6050 Attitude sensor, which integrates an Accelerometer and Gyroscope.

25.1. Project Read a MPU6050 Sensor Module

In this project, we will read Acceleration and Gyroscope Data of the MPU6050 Sensor.

25.1.1. Component List

Raspberry Pi (with 40 GPIO) x1
GPIO Extension Board & Ribbon Cable x1
Breadboard x1

Jumper Wires x4

MPU6050 x1

25.1.2. Component knowledge

25.1.2.1. MPU6050

MPU6050 Sensor Module is a complete 6-axis Motion Tracking Device. It combines a 3-axis Gyroscope, a 3-axis Accelerometer and a DMP (Digital Motion Processor) all in a small package. The settings of the Accelerometer and Gyroscope of MPU6050 can be changed. A precision wide range digital temperature sensor is also integrated to compensate data readings for changes in temperature, and temperature values can also be read. The MPU6050 Module follows the I2C communication protocol and the default address is 0x68.

The port description of the MPU6050 Module is as follows:

Pin name	Pin number	Description
VCC	1	Positive pole of power supply with voltage 5V
GND	2	Negative pole of power supply
SCL	3	I2C communication clock pin
SDA	4	I2C communication data pin
XDA	5	I2C host data pin which can be connected to other devices.
XCL	6	I2C host clock pin which can be connected to other devices.
AD0	7	I2C address bit control pin. Low level: the device address is 0x68 High level: the device address is 0x69
INT	8	Output interrupt pin

For more detail, please refer to the MPU6050 datasheet.

MPU6050 is widely used to assist with balancing vehicles, robots and aircraft, mobile phones and other products which require stability to control stability and attitude or which need to sense same.

25.1.3. Circuit

Note that the power supply voltage for MPU6050 module is 5V in this circuit.

Schematic diagram

MPU6050_Sc

Hardware connection. If you need any support,please feel free to contact us via:

support@freenove.com

MPU6050_Fr

25.1.4. Code

25.1.4.1. C Code MPU6050RAW

First, observe the project result, and then learn about the code in detail.

Hint

If you have any concerns, please contact us via: support@freenove.com

Use cd command to enter 25.1.1_MPU6050RAW directory of C code.

$ cd ~/Freenove_Kit/Code/C_Code/25.1.1_MPU6050

Use following command to compile MPU6050RAW.c, MPU6050.cpp and I2Cdev.cpp, and generate executable file MPU6050RAW.

$ gcc MPU6050RAW.cpp MPU6050.cpp I2Cdev.cpp -o MPU6050RAW

Then run the generated file “MPU6050RAW”.

$ sudo ./MPU6050RAW

After the program is executed, the Terminal will display active accelerometer and gyroscope data of the MPU6050, as well as the conversion to gravity acceleration and angular velocity as units of data. As shown in the following figure:

The following is the program code:

/**********************************************************************
* Filename    : MPU6050RAW.c
* Description : Read data of MPU6050
* Author      : www.freenove.com
* modification: 2019/12/27
**********************************************************************/
#include <stdio.h>
#include <stdint.h>
#include <unistd.h>
#include "I2Cdev.h"
#include "MPU6050.h"

MPU6050 accelgyro;      //creat MPU6050 class object

int16_t ax, ay, az;     //store acceleration data
int16_t gx, gy, gz;     //store gyroscope data

void setup() {
    // initialize device
    printf("Initializing I2C devices...\n");
    accelgyro.initialize();     //initialize MPU6050

    // verify connection
    printf("Testing device connections...\n");
    printf(accelgyro.testConnection() ? "MPU6050 connection successful\n" : "MPU6050 connection failed\n");
}

void loop() {
    // read accel/gyro values of MPU6050
    accelgyro.getMotion6(&ax, &ay, &az, &gx, &gy, &gz);
    // display accel/gyro x/y/z values
    printf("a/g: %6hd %6hd %6hd   %6hd %6hd %6hd\n",ax,ay,az,gx,gy,gz);
    printf("a/g: %.2f g %.2f g %.2f g   %.2f d/s %.2f d/s %.2f d/s \n",(float)ax/16384,(float)ay/16384,(float)az/16384,
        (float)gx/131,(float)gy/131,(float)gz/131);
}

int main()
{
    setup();
    while(1){
        loop();
    }
    return 0;
}

Two library files “MPU6050.h” and “I2Cdev.h” are used in the code and will be compiled with others. Class MPU6050 is used to operate the MPU6050 Sensor. When used, first it initiates an object.

MPU6050 accelgyro;

In the setup function, the MPU6050 is initialized and the result of the initialization will be tested.

void setup() {
    // initialize device
    printf("Initializing I2C devices...\n");
    accelgyro.initialize();     //initialize MPU6050

    // verify connection
    printf("Testing device connections...\n");
    printf(accelgyro.testConnection() ? "MPU6050 connection successful\n" : "MPU6050 connection failed\n");
}

In the loop function, read the original data of MPU6050, display them and then convert the original data into the corresponding acceleration and angular velocity values, then display the converted data out.

void loop() {
    // read accel/gyro values of MPU6050
    accelgyro.getMotion6(&ax, &ay, &az, &gx, &gy, &gz);
    // display accel/gyro x/y/z values
    printf("a/g: %6hd %6hd %6hd   %6hd %6hd %6hd\n",ax,ay,az,gx,gy,gz);
    printf("a/g: %.2f g %.2f g %.2f g   %.2f d/s %.2f d/s %.2f d/s \n",(float)ax/16384,(float)ay/16384,(float)az/16384,
        (float)gx/131,(float)gy/131,(float)gz/131);
}

Finally, the main functions, called setup function and loop function respectively.

int main()
{
    setup();
    while(1){
        loop();
    }
    return 0;
}

About class MPU6050:

Class MPU6050

This is a class library used to operate the MPU6050, which can directly read and set the MPU6050. Here are its functions:

MPU6050()/MPU6050(uint8_t address);

Constructor. The parameter is I2C address, and the default I2C address is 0x68.

void initialize();

Initialization function, used to wake up MPU6050. Range of accelerometer is ±2g and range of gyroscope is ±250 degrees/sec.

void getMotion6(int16_t* ax, int16_t* ay, int16_t* az, int16_t* gx, int16_t* gy, int16_t* gz);

Get the original data of accelerometer and gyroscope.

int16_t getTemperature();

Get the original temperature data of MPU6050.

For details about more relevant member functions, pleases refer to MPU6050.h or visit: https://github.com/jrowberg/i2cdevlib