You’ve bought an Arduino starter kit, you’ve followed all the basic Arduino guides, but now you’ve hit a stumbling block – you need more bits and bobs to realise your electronics dream. Luckily, if you have an Arduino board, you can simply stack functionality on top in the form of Shields. Shields are specifically designed for the Uno board to be the same shape and pin alignment; you simply plug them on, and you have instant upgrade of functionality.
Ethernet Shield ($45)
An official shield from the Arduino creators, the Ethernet shield is a great way to make your Arduino project work independently of a computer whilst still maintaining network contact to talk to the world. Another interesting addition this board gives you is a MicroSD card slot; so if your project requires large data files such as video or mp3s, or simply patterns for your LED cube, you can store them on there.
You can even host a website, which you can use to present your project’s sensor information to the world.
Before you buy, be warned: the Ethernet shields are version specific. I purchased a v3 one only to find it wouldn’t fit on my v2 Uno board – two additional pins were added in v3 of the Uno. Since the Ethernet Shield is actually more expensive than the Uno, if you find yourelf in this situation then the simplest solution is just to buy a new Uno to use with the Ethernet, then keep your old board for other projects.
Or you could just check the version number on the back of your board before buying, but where’s the fun in that?
4 Relay Shield ($20)
Now you really can turn your kettle on over the Internet!
Relays are a key component in a lot of home automation Arduino projects simply because they allow you to switch on and off higher voltage circuits, such as mains powered devices – electronically isolating one circuit from the other. You’ve probably already played with a single relay in your starter kit, and you’ll know that you need a few other components like a transistor or opto-coupler, and a diode. If you want more than one relay, your prototyping board gets very busy very quickly.
This 4 Relay Shield solves that by neatly packing 4 sets of relays and the necessary bits onto a single board. Using 4 IO pins, you then simply pull a pin HIGH to switch the corresponding relay. Each relay will handle up to 3 amps, though you can of course use relays with low power circuits too, as a replacement for an on-off switch. This particular shield can also be hooked up to an RFBee instead of an Arduino for radio control.
It goes without saying – if you’re using this to switch mains powers devices directly, be extremely careful when handling the project, as it’s basically like leaving the cover off a wall socket.
Warning: In the picture above, I’ve used stackable pin risers to avoid contact with the USB port. The legs from the relay protrude slightly underneath, and if carrying a high voltage, are likely to fry your Arduino, or even worse, your computer. Some people use insultating tape to cover the legs instead.
The Protoshield doesn’t really do anything, which is why it looks so plain. However, if you’ve been using a breadboard to lay out and prototype your project and now wish to make it into something more permanent, you can solder everything to one of these, then continue stacking other shields on top. Essential!
The advantages of having an LCD screen for your project are obvious – your Arduino can output messages. However, these typically require 7 or more IO pins, drastically cutting the number available to you. This shield is built using the I2C communications bus (a serial protocol used by many devices), meaning it only uses 2 pins, and can even be linked to other components on the same bus (the signal is passed through, down the chain).
In addition to the screen, 4 directional and a “select” button are provided, giving you an interactive interface without needing to be hooked up to a PC. If monotone isn’t your thing, upgrade to this 1.8 inch TFT 18-bit color screen.
Bear in mind that not all shields are fully stackable; some will need to go on the top of the stack as they don’t provide pins on top (or don’t make sense going in the middle of the stack, like an LCD screen).
Are you just getting started with an Arduino? No problem, we have quite a fewhere for you to try. Have you used an Arduino shield? If so, let us know in the comments which one and what you built with it!
Image Credit: John@TronixStuff
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