Arduino Interfacing with Gyro Sensor: Guide and Code

This document explains how to interface an Arduino board with a gyro sensor, including the necessary diagram, working principles, and Arduino code.

Introduction

Gyro sensors are commonly used in wearable devices to determine rotational motion and changes in orientation. Modern gyro sensors often come with an I2C interface, allowing for easy integration with Arduino boards, microcontrollers, or microprocessors. Typical applications include angular velocity sensing, angle sensing, and control mechanisms.

About the Gyro Sensor

The gyro sensor used in this example is the MPU-6050. It provides data for the x-axis, y-axis, and z-axis simultaneously. The code will parse this data to extract individual values.

The I2C bus protocol uses two lines for communication between master and slave devices: SDA (Serial Data) and SCL (Serial Clock).

About the Arduino Board

• The Arduino Uno features an ATmega328 microcontroller from ATMEL, containing 32 KB of flash memory, 2 KB of RAM, an 8-bit wide CPU, and 1 KB of EEPROM.
• It includes 6 analog pins for reading voltage, converting analog measurements to digital.
• Digital pins (0 to 13) can function as either input or output.
• It supports various interfaces such as I2C, digital pins, analog pins, serial communication, and USB.
• It also has a reset pin, power port, crystal oscillator, and Tx/Rx LEDs.
• This open-source prototype board can be easily programmed using the Arduino IDE via USB.
• The IDE uses a simplified C++ program.
• The board requires 5V DC, powered by an AC/DC adapter or battery.

Arduino Interfacing with Gyro Sensor: Diagram and Working

Figure 1 shows the interfacing of the gyro sensor with the Arduino board.

Arduino Gyro Sensor Interface Code

The following Arduino code is compiled and uploaded to the Arduino board using the Arduino IDE. It reads data from the MPU-6050 gyro sensor connected to the Arduino.

#include <Wire.h>

const int MPU = 0x68; // MPU6050 I2C address
float AccX, AccY, AccZ;
float GyroX, GyroY, GyroZ;
float accAngleX, accAngleY, gyroAngleX, gyroAngleY, gyroAngleZ;
float roll, pitch, yaw;
float AccErrorX, AccErrorY, GyroErrorX, GyroErrorY, GyroErrorZ;
float elapsedTime, currentTime, previousTime;
int c = 0;

void setup() {
  Serial.begin(19200);
  Wire.begin();                      // Initialize comunication
  Wire.beginTransmission(MPU);       // Start communication with MPU6050
  // MPU=0x68
  Wire.write(0x6B);                  // Talk to the register 6B
  Wire.write(0x00);                  // Make reset - place a 0 into the 6B register
  Wire.endTransmission(true);        //end the transmission
}

void loop() {
  // === Read acceleromter data === //
  // Wire.beginTransmission(MPU);
  Wire.write(0x3B); // Start with register 0x3B (ACCEL_XOUT_H)
  Wire.endTransmission(false);
  Wire.requestFrom(MPU, 6, true); // Read 6 registers total, each axis value is stored in 2 registers
  //For a range of +-2g, we need to divide the raw values by 16384, according to the datasheet
  AccX = (Wire.read() << 8 | Wire.read()) / 16384.0; // X-axis-value
  AccY = (Wire.read() << 8 | Wire.read()) / 16384.0; // Y-axis-value
  AccZ = (Wire.read() << 8 | Wire.read()) / 16384.0; // Z-axis-value

  // Calculating Roll and Pitch from the accelerometer data
  accAngleX = (atan(AccY / sqrt(pow(AccX, 2) + pow(AccZ, 2))) * 180 / PI) - 0.58; // AccErrorX ~(0.58) See the calculate_IMU_error()custom function for more details
  accAngleY = (atan(-1 * AccX / sqrt(pow(AccY, 2) + pow(AccZ, 2))) * 180 / PI) + 1.58; // AccErrorY ~(-1.58)

  // === Read gyroscope data === //
  previousTime = currentTime;        // Previous time is stored before the actual time read
  currentTime = millis();            // Current time actual time read
  elapsedTime = (currentTime - previousTime) / 1000; // Divide by 1000 to get seconds
  Wire.beginTransmission(MPU);
  Wire.write(0x43); // Gyro data first register address 0x43
  Wire.endTransmission(false);
  Wire.requestFrom(MPU, 6, true); // Read 4 registers total, each axis value is stored in 2 registers
  GyroX = (Wire.read() << 8 | Wire.read()) / 131.0; // In 250deg/s range we have to divide first the raw value by 131.0, according to the datasheet
  GyroY = (Wire.read() << 8 | Wire.read()) / 131.0;
  GyroZ = (Wire.read() << 8 | Wire.read()) / 131.0;

  // Correct the outputs with the calculated error values
  GyroX = GyroX + 0.56; // GyroErrorX ~(-0.56)
  GyroY = GyroY - 2; // GyroErrorY ~(2)
  GyroZ = GyroZ + 0.79; // GyroErrorZ ~ (-0.8)

  // Currently the raw values are in degrees per seconds, deg/s, so we need to multiply
  //by sendonds (s) to get the angle in degrees
  gyroAngleX = gyroAngleX + GyroX * elapsedTime; // deg/s * s = deg
  gyroAngleY = gyroAngleY + GyroY * elapsedTime;
  yaw =  yaw + GyroZ * elapsedTime;

  // Complementary filter - combine acceleromter and gyro angle values
  roll = 0.96 * gyroAngleX + 0.04 * accAngleX;
  pitch = 0.96 * gyroAngleY + 0.04 * accAngleY;

  // Print the values on the serial monitor
  Serial.print(roll);
  Serial.print("/");
  Serial.print(pitch);
  Serial.print("/");
  Serial.println(yaw);
}

Conclusion

This document has covered the interfacing of a gyro sensor with an Arduino Uno board. Arduino boards are also used for interfacing various other types of sensors for different applications. Typical sensors interfaced with Arduino include sound sensors, heartbeat sensors, LDR sensors, GPS sensors, color sensors, pH sensors, etc.