Wire library for I2C in Arduino - Mini Project: Build & Apply

Using the Wire Library for I2C Communication

📖 Scenario: You want to communicate between two Arduino boards using the I2C protocol. The Wire library helps you send and receive data easily over I2C.In this project, you will set up a simple I2C master device that sends a number to a slave device.

🎯 Goal: Build a simple Arduino program that uses the Wire library to send a byte of data from a master device to a slave device over I2C.

📋 What You'll Learn

Include the Wire library

Initialize the Wire library as a master

Send a byte of data to a slave device with address 8

Print a message when data is sent

💡 Why This Matters

🌍 Real World

I2C is used to connect sensors, displays, and other devices to microcontrollers in many electronics projects.

💼 Career

Understanding I2C and the Wire library is important for embedded systems developers and hardware engineers working with microcontrollers.

1

Include the Wire library and start I2C as master

Write #include <Wire.h> at the top and in setup(), start the Wire library as a master using Wire.begin().

Arduino

#include 

void setup() {
  // Start I2C as master
  // Your code here
}

void loop() {
  // Your code here
}

Hint

Use #include <Wire.h> to include the library. Then call Wire.begin() inside setup() to start as master.

2

Create a variable for the slave address

Create a variable called slaveAddress and set it to 8 above setup().

Arduino

#include 

// Define slave address
// Your code here

void setup() {
  Wire.begin();
}

void loop() {
  
}

Hint

Use const int slaveAddress = 8; to store the slave device address.

3

Send a byte of data to the slave device

In loop(), use Wire.beginTransmission(slaveAddress), then send the byte 42 with Wire.write(42), and finally call Wire.endTransmission().

Arduino

#include 

const int slaveAddress = 8;

void setup() {
  Wire.begin();
}

void loop() {
  // Send data to slave
  // Your code here
}

Hint

Use Wire.beginTransmission() with the slave address, then Wire.write() to send data, and Wire.endTransmission() to finish.

4

Print a message after sending data

Add Serial.begin(9600) in setup(). After sending data in loop(), add Serial.println("Data sent") to print a confirmation message.

Arduino

#include 

const int slaveAddress = 8;

void setup() {
  Wire.begin();
  // Start serial communication
  // Your code here
}

void loop() {
  Wire.beginTransmission(slaveAddress);
  Wire.write(42);
  Wire.endTransmission();
  // Print confirmation
  // Your code here
}

Hint

Use Serial.begin(9600) in setup() and Serial.println("Data sent") after sending data to show the message.