Getting Started with Arduino

Assembling the Circuit

Figure 6-2 shows how to assemble the circuit. You need to use 10K resistors for all of the resistors shown in the diagram, although you could get away with lower values for the resistors connected to the LEDs.

Remember from the PWM example in Chapter 5 that LEDs are polarized: in this circuit, the long pin (positive) should go to the right, and the short pin (negative) to the left. (Most LEDs have a flattened negative side, as shown in the figure.)

Figure 6-2. The "Arduino Networked Lamp" circuit

Build the circuit as shown, using one red, one green, and one blue LED. Next, load the sketches into Arduino and Processing, then run the sketches and try it out. If you run into any problems, check Chapter 7, "Troubleshooting".

Now let's complete the construction by placing the breadboard into a glass sphere. The simplest and cheapest way to do this is to buy an IKEA "FADO" table lamp. It's now selling for about US$14.99/ €14.99/£8.99 (ahh, the luxury of being European).

Instead of using three separate LEDs, you can use a single RGB LED, which has four leads coming off it. You'll hook it up in much the same way as the LEDs shown in Figure 6-2, with one change: instead of three separate connections to the ground pin on Arduino, you'll have a single lead (called the "common cathode") going to ground.

SparkFun sells a 4-lead RGB LED for a few dollars (www.sparkfun.com; part ...