Activity 2: Write a Simple "Hello!" Sketch

To get started using Codebender instead of the Arduino IDE, click here.

Here is a screen capture of the Arduino Development Environment edit pane on the left, containing a simple sketch that sends a “Hello!” message to the Serial Monitor window on the right. 

  • Open your Arduino software and carefully type in the code:
void setup()


void loop()
  //Add code that repeats automatically here.
  • Be sure you have capitalized “Serial” both times, or the sketch won’t work.
  • Also, notice in the figure that the sketch uses parentheses() and curly braces {}. Be sure to use the right ones in the right places!

Simple Arduino Sketch prints "Hello!" to the Serial Monitor

  • Click the Verify button to make sure your code doesn’t have any typing errors. 
  • Look for the “Binary sketch size” text in the message pane.
  • If it’s there, your code compiled and is ready to upload to the Arduino.
  • If there’s a list of errors instead, it’s trying to tell you it can’t compile your code. So, find the typing mistake and fix it!
  • Click the Upload button. The status line under your code will display “Compiling sketch…,”  “Uploading…,” and then “Done uploading.”
  • After the sketch is done uploading, click the Serial Monitor button. 
  • If the Hello message doesn’t display as soon as the Serial Monitor window opens, check for the “9600 baud” setting in the lower right corner of the monitor.
  • Use File → Save to save your sketch.  Give it the name HelloMessage.

Now you are ready to see How the Hello Sketch Code Works.