🔗 Master-Slave I2C Communication Between Two Arduinos – Full Guide + Code

Want to connect two Arduino boards to communicate seamlessly? Using I2C (Inter-Integrated Circuit) communication, you can send and receive data between a master Arduino and a slave Arduino with just two wires. Whether you're building a sensor network, multi-Arduino system, or an IoT prototype, I2C makes it super easy!

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🧰 Components Required

• ✅ 2x Arduino Uno or Nano

• ✅ Jumper wires (Male to Male)

• ✅ Common Ground Connection

• ✅ (Optional) OLED Display or other I2C devices

• ✅ Android phone to test/control via app

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📲 Bonus: Download the Plysmotix Android App

Make your I2C projects smarter with our Android app:

• ✅ Send/receive data via Bluetooth

• ✅ Monitor serial output remotely

• ✅ Access DIY tutorials

• ✅ Shop components anytime

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🔌 I2C Wiring Between Two Arduinos

Pin on Master	Pin on Slave
A4 (SDA)	A4 (SDA)
A5 (SCL)	A5 (SCL)
GND	GND

📌 Use pull-up resistors (4.7kΩ) on SDA and SCL for longer wire lengths.

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💻 Arduino I2C Master Code

Arduino_Basic_Code_I2C_Communication_Master-Slave

Filename: Master_Code_Arduino_1.cpp

#include <Wire.h>

void setup() {
  Wire.begin(); // Join I2C bus as master
  Serial.begin(9600);
}

void loop() {
  Wire.beginTransmission(8); // Address of slave
  Wire.write("Hello, Slave!");
  Wire.endTransmission();
  Serial.println("Message sent!");
  delay(1000);
}

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💻 Arduino I2C Slave Code

Arduino_Basic_Code_I2C_Communication_Master-Slave

Filename: Slave_Code_Arduino_2.cpp

#include <Wire.h>

void setup() {
  Wire.begin(8); // Set address as 8
  Wire.onReceive(receiveEvent);
  Serial.begin(9600);
}

void receiveEvent(int bytes) {
  while (Wire.available()) {
    char c = Wire.read();
    Serial.print(c);
  }
  Serial.println();
}

void loop() {}

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🧠 How It Works

• The Master Arduino sends a message "Hello, Slave!" every second to the slave with address 8.

• The Slave Arduino receives and prints the message using the onReceive() interrupt handler.

• You can easily scale this system to control multiple slaves or sensors.

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🔥 Real-World Applications

• 🌡️ Distributed sensor networks

• 🚪 Multi-point home automation systems

• 🧠 Modular robotics communication

• 🎛️ Remote control of actuators/devices

• 📶 I2C with Bluetooth/Wi-Fi master for IoT projects

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🛒 Why Buy I2C Components from Plysmotix.in?

• 🔌 Genuine Arduino boards (Uno, Mega, Nano)

• 📦 I2C modules like OLED, RTC, sensors

• 🔧 Jumper wires, breadboards, and resistors

• 🧪 DIY kits with preloaded I2C codes

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📲 Unlock More Features with Plysmotix Android App

Use the app to:

• View real-time I2C data

• Store communication logs

• Control master Arduino wirelessly

• Access I2C tutorials offline

• Order compatible sensors and boards

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✅ Conclusion

I2C communication between two Arduino boards is an essential skill for any electronics hobbyist or developer. It's fast, efficient, and perfect for building scalable systems.

So what are you waiting for?

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