Chapter 8: Serial Communication

In many projects, your Arduino won't operate in isolation. Whether you're sending data to a computer, communicating with other microcontrollers, or controlling devices, serial communication often plays a vital role. This chapter sheds light on the ins and outs of serial communication with Arduino.

Basics of Serial Communication

Serial communication is a method where data is transferred one bit at a time, sequentially, over a communication channel or data bus. This is in contrast to parallel communication, where multiple bits are sent simultaneously. For many Arduino boards, especially those with only one processor, serial communication is a lifeline, enabling interaction with a host computer or other devices.

Arduino Serial Library: Sending and Receiving Data

The Arduino platform provides the Serial library, making it simple to communicate through the board's serial port. Here are the key functions:

1. Serial.begin(baud_rate): Initializes serial communication at a specified baud rate (speed). Common rates include 9600, 115200, etc.

void setup() {
  Serial.begin(9600);   // Start serial at 9600 bps
}

2. Serial.print(data): Send data over the serial port without a new line at the end.

3. Serial.println(data): Send data followed by a new line.

void loop() {
  Serial.println("Hello, World!");  // Send a message continuously
  delay(1000);                       // Wait a second
}

4. Serial.available(): Returns the number of bytes available to read.

5. Serial.read(): Reads incoming serial data.

char receivedChar;   // Store received character

void loop() {
  if (Serial.available() > 0) {            // Check if data is available to read
    receivedChar = Serial.read();          // Read the incoming character
    Serial.print("Received: ");
    Serial.println(receivedChar);          // Echo the character back to the Serial Monitor
  }
}

Interfacing with a Computer or Other Devices

1. Serial Monitor:
Arduino IDE includes a Serial Monitor that allows you to send and receive text data. It's particularly useful for debugging or simple interactions with your board.

To use:

• Upload your Arduino code with Serial commands.
• Click on the magnifying glass icon in the top right of the Arduino IDE.
• Ensure the baud rate in the Serial Monitor matches your code.

2. Interfacing with Other Devices:
Arduino can communicate with various devices that support serial communication, like GPS modules, GSM shields, or even other microcontrollers. The key is to ensure both devices operate at the same baud rate and share a common ground.

Example - Interfacing with another Arduino:

Master Arduino:

void setup() {
  Serial.begin(9600);   // Start serial at 9600 bps
}

void loop() {
  Serial.println("Hello from Master!");  // Send a message
  delay(1000);                           // Wait a second
}

Slave Arduino:

void setup() {
  Serial.begin(9600);   // Start serial at 9600 bps
}

void loop() {
  if (Serial.available()) {
    String message = Serial.readString();  // Read the incoming string
    // Process the received message, e.g., turn on an LED, etc.
  }
}

Conclusion

Serial communication is a linchpin in the Arduino toolkit, enabling data transfer between the board and a plethora of devices. From simple debugging to complex device interactions, mastering serial communication empowers you to take your projects to new horizons, achieving richer interactivity and broader functionality.