Get the number of bytes (characters) available for reading over the serial port.
None
how many bytes are available to read in the serial buffer, or 0 if there arent any. If any data has come in, Serial.available() will be greater than 0. The serial buffer can hold up to 64 bytes.
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 = Serial.read(); // say what you got: Serial.print("I received: "); Serial.println(incomingByte, DEC); } }