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Reads incoming serial data. inherits from the Stream utility class.



Serial: serial port object. See the list of available serial ports for each board on the Serial main page.


The first byte of incoming serial data available (or -1 if no data is available) - int.

Example Code

int incomingByte = 0; // for incoming serial data

void setup() {
  Serial.begin(9600); // opens serial port, sets data rate to 9600 bps

void loop() {
  // send data only when you receive data:
  if (Serial.available() > 0) {
    // read the incoming byte:
    incomingByte =;

    // say what you got:
    Serial.print("I received: ");
    Serial.println(incomingByte, DEC);