How do you communicate between two Arduino boards?

#arduino #uart #i2c #spi

Communicating between two Arduino boards can be done in several ways, depending on your requirements like speed, distance, and data complexity. Here's a summary of the main communication methods:

🔌 1. Serial Communication (UART)

Wiring: Connect TX of one Arduino to RX of the other and vice versa. Also, connect GNDs.
Library: Serial, SoftwareSerial (for additional ports)
Pros: Simple, built-in on most boards
Cons: Only point-to-point, limited distance, uses serial port (shared with USB on some boards)

cpp

// On Sender
Serial.println("Hello Arduino");

// On Receiver
if (Serial.available()) {
  String msg = Serial.readString();
  Serial.println("Received: " + msg);
}

🧠 2. I2C (Inter-Integrated Circuit)

Wiring: SDA to SDA, SCL to SCL, and GNDs connected
Library: Wire.h
Pros: One master can talk to multiple slaves; relatively easy to implement
Cons: Limited cable length (~1 meter), slower than SPI

cpp

// Master
Wire.beginTransmission(8); // Address of the slave
Wire.write("Hi!");
Wire.endTransmission();

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

⚡ 3. SPI (Serial Peripheral Interface)