Prints data to the serial port as human-readable ASCII text followed by a carriage return character (ASCII 13, or '\r') and a newline character (ASCII 10, or '\n'). This command takes the same forms as Serial.print().

Serial.println(val, format);


  • val: the value to print - any data type
  • format: specifies the number base (for integral data types) or number of decimal places (for floating point types)

println() returns the number of bytes written, though reading that number is optional - size_t (long)

//reads an analog input on analog in A0, prints the value out.

int analogValue = 0;    // variable to hold the analog value

void setup()
  // Make sure your Serial Terminal app is closed before powering your device
  // Wait for a USB serial connection for up to 30 seconds
  waitFor(Serial.isConnected, 30000);

void loop() {
  // read the analog input on pin A0:
  analogValue = analogRead(A0);

  // print it out in many formats:
  Serial.println(analogValue);       // print as an ASCII-encoded decimal
  Serial.println(analogValue, DEC);  // print as an ASCII-encoded decimal
  Serial.println(analogValue, HEX);  // print as an ASCII-encoded hexadecimal
  Serial.println(analogValue, OCT);  // print as an ASCII-encoded octal
  Serial.println(analogValue, BIN);  // print as an ASCII-encoded binary

  // delay 10 milliseconds before the next reading: