One of the great things about Arduino systems is they enable us to try ideas and experiment with concepts. At a software level this is simple – write, compile and download. Hardware components, however, can be more time consuming as you either have to wire up a temporary breadboard or you have to build dedicated circuits.
There is a simple way to make the hardware more ‘plug and play’ by building small modules with a simple standard interface that can be combined to create bigger systems. The outcome is a library of standard modules that are easily connected to the Arduino to prototype ideas without fiddling with breadboard wires for the simple stuff.
There are several key components involved in creating the interchangeable hardware system.
The first part is a sensor shield. This type is generally known as “Sensor Shield V4” and is available in most of the online sellers of Arduino hardware (eg, eBay) and cost a few dollars. These shields standardise all the Arduino digital and analog pins into a 3 pin connector interface with Ground, Voltage and Signal (GVS) signals.
Standard 3-pin female to female Dupont connectors are used to connect the different hardware components (typically sensors, switches and/or LEDs) to the sensor shield. Once again, these are inexpensive and available from many online sources.
Hardware and Sensor Modules
The beauty of the GVS interface is that is works for the vast majority of simple hardware components. Many hardware and sensor kits are available using this standard interface. These are a quick way to start building a collection of standard hardware. Additinal or more specialised modules can be purchased or made, as described below.
DIY Hardware Modules
Making your own modules may not be cheaper than buying one, but it is a good way to learn how a sensor is wired and how to read data sheets, which often contain the simple circuits that are used to implement these modules. DIY is also faster than waiting for a mail delivery!
I build the simple circuits on small 1″ (25mm) square circuit boards that are sourced from online stores, usually 24 at a time, for a cost of a few cents each.
On these I mount mount a 3 pin GVS connector and the circuit of choice. Modules may have switches, LEDs, pots, lasers, IR detectors, temperature sensors, etc, mounted so that I can rapidly connect and use them. Examples of these simple DIY boards are shown below (cyan colored links are below the board; blue colored links are above the board).
UPDATE 7 April 2018
It seems that these 1″ square boards are now hard to purchase online (see the comments below). I have created similar boards that you can order from a Seeed Studio (a PCB manufacturer) through this link. The boards are made 9 per sheet, with the minimum order being 10 sheets (ie, 90 boards) for a few dollars plus delivery. The boards can be separated by just snapping them apart once you get them.
Dual Tact Switch
Combined LED/Tact Switch
A combination of the LED and Tact circuits on one board.
Light Dependent Resistor
And, finally, examples of how these can be used during project development.