When I used Serial.println() in the code I naively believed I would see the characters that I sent displayed on that little black area just under the interface (just like a terminal).

#include <Servo.h>

int moveServo;

Servo myservo;

void setup()
  Serial.println("      Hello Earth");

void loop() {

Can someone tell me just where Hello Earth would be displayed?

2 Answers 2


The IDE on your computer has a menu item under the tools menu called "Serial Monitor." On my Mac, at least, it is indeed a black area under the source editor for the current sketch.

It won't work unless you call the Serial.begin() function in your setup method before the first Serial.print()/println()/write() function call.

Something like this:

//Set up the serial port @ 9600 baud for display back to the computer
Serial.println("Hello world!":);

You can open the serial console in the Arduino IDE by pressing ctrl-shift-M (as in Monitor) or selecting it in the menu.

Also, to use the serial interface, you have to initialize it using Serial.begin(9600); in setup() before calling any other function which writes to it. You can use any other baud rate - but this is the default in the Arduino IDE, if you change it, you should change it in the IDE too.

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