Arduino All-in-One Getting Started Guide

Step 2 Wiring the Blinky Lights

I've broken the circuit down in such a way that we will be wiring up our output (the blinky lights) completely separately from our input (the pushbutton switch). Makes it easier to understand if you're just starting out.

First, a note and word of caution. Newer Arduino boards have an LED right on the board itself or at least a resistor connected to pin 13 so that you can stick an LED right between pin 13 and ground (GND).

This is NOT true for the other pins! If you connect LED's or other circuits on other pins you must be certain to protect your board from excessive currents or full-out short circuits. You can fry your Arduino!

Personally, I recommend that you always use a resistor when experimenting. You don't want to accidentally short to ground, so at least connect a low value resistor to the ground pin. Better safe than sorry.

In this circuit we are using pins 11,12 and 13 as digital outputs (5V) to power the LED's. The negative post of each LED connects across a single shared resistor and then to ground. In my circuit I'm using a 150 ohm resistor (it was just a convenient grab from my parts bin). You can use other values here -- just don't go too extreme so that you don't either (a) keep the LED from lighting or (b) push too much current through your Arduino.

If you run the Arduino "blink" sketch from step one you should now notice that one of your LED's is blinking. If not, you should check back over your wiring and components. A diagram for this very simple circuit is below.

Comments

[ekhurley]

I just bought The getting started book and a kit, and they keep mentioning using a resistor on some pins but not others, thank you for finally explaining why.