YOU NOW HAVE the Arduino software installed and have uploaded your first sketch to make sure everything is set up correctly. (If you haven’t done that, it would be best to go to Adventure 1 and do that now!) It’s great telling the Arduino to control something like flashing lights, but the real fun with Arduino starts when your projects become interactive. There are a couple things that need to happen before a project can become interactive: first the Arduino needs to know something about what is happening in the real world; then the Arduino code needs to do something based on that information.

You’re going to travel a long way in this adventure! You start by controlling multiple LEDs and then you print some messages from the Arduino to the computer. After that, you read in information from a sensor and print that information to the computer. Finally, you put all of that knowledge together to build a terrific status message sign, which will have multiple messages and a control knob you can turn to choose what message you want to display—perfect for welcoming or sending away visitors at your whim.

What You Need

You first find out how to add more LEDs to your circuit and then how to use a sensor called a potentiometer. The following list tells you what you need, and Figure 2-1 shows the electronic components. Remember, Appendix B includes suggestions of where you can buy everything. ...

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