There are a multitude of options for connecting devices to the Raspberry Pi. We will touch on a few of these in the following sections. You can purchase these devices if you wish and expand the options that are available for you on the Raspberry Pi.
Regardless of whether you purchase a shield or not, you will need the components listed under the Connecting directly to the GPIO pins section if you wish to run the programs in this chapter.
First, we will look at prototyping shields.
A number of prototyping shields are available on the market for the Raspberry Pi. A prototyping shield is an electronic component that sits on top of the Raspberry Pi and is connected to the GPIO pins.
Part of the device acts as a breadboard, which allows you to connect a variety of electronic components to it and control them via applications running on Raspbian.
Some examples of prototyping plates include:
- Pi Cobbler
- Adafruit Prototyping Pi Plate Kit
- RKPT Lucia
- Humble Pi
The Pi Cobbler is a popular choice and can be found on the Adafruit website. Unlike the other devices, it does not sit on top of the Raspberry Pi 2, but rather uses a ribbon cable to attach a breadboard to the GPIO pins.
If you would prefer not to use a plate, this is the best option. It can be found at https://www.adafruit.com/products/914.
The next shield we will look at is the Adafruit Prototyping Pi Plate Kit. This is a set of components that can be put together into a plate. This plate then sits on top of the Raspberry Pi.
Once assembled, electronic components can then be attached to the plate. This allows you to build a device directly connected to the Raspberry Pi.
The plate can be obtained from Adafruit industries available at https://www.adafruit.com/products/801.
A similar device to the Prototyping Pi Plate Kit is the RKPT Lucia available from the RK Education website at http://www.rkeducation.co.uk/RKPT-lucia.php.
This kit also requires some soldering to put together.
Finally we come to the Humble Pi. This device can be found at http://shop.ciseco.co.uk/k001-humble-pi/.
Once the kit has been built in a similar way to the previous shields, it can be attached on top of the Raspberry Pi 2 and you can then build projects directly on top of it.
Let's now look at an alternative to these types of shield.
The next device we will be looking at allows us to interface with hardware devices designed to work with Arduino.
Arduino is a popular open source microcontroller and will be discussed later in this book when we look at how we can communicate between the Raspberry Pi and other microcontrollers.
A popular feature of Arduino is the many shields that can be attached to it. These shields contain pre-soldered components such as relays, motors, and WiFi support.
You can read more about these on the official Arduino website at https://www.arduino.cc/en/Main/ArduinoShields.
Using the Cooking Hacks Arduino bridge shield, we can connect these third party Arduino shields to the Raspberry Pi.
The following image shows some of the features of the Cooking Hacks shield:
Image courtesy of Cooking Hacks
Using the C++ library provided with the shield's hardware, we can write applications that control the Arduino shields via the Raspberry Pi.
The shield can be purchased from the Cooking Hacks website at https://www.cooking-hacks.com/raspberry-pi-to-arduino-shield-connection-bridge.
Additionally, Arduino shields are available from a variety of manufacturers and stores. A list of over 127 different shields can be found at http://shieldlist.org/.
What if we don't have a shield? Let's look at our final alternative.
Another option is to connect to the GPIO pins directly using wires and a breadboard. In this chapter, we will write programs that use this methodology. You can always adapt these to use one of the other hardware options presented earlier in this chapter.
In this instance you will need a breadboard, wires, and the components you wish to control.