Extensions for the Raspberry Pi

Let There Be Light

The Raspberry Pi is supposed to be getting an official touchscreen before too long. The user will simply plug the touchscreen into the Rasp Pi board, thereby transforming the nanocomputer into a type of tablet PC [5]. Because of the increased height of the tandem setup the Raspberry Pi Foundation foresees application of the touchscreen primarily in embedded systems. The screen is supposed to have a resolution of 640x480 pixels.

The C-Berry screen from Admatec is a TFT display screen (Figure 2) that has been available for purchase for some time [6]. It costs around $45 and is connected via the SPI port. However, the display has limited resolution of about 320x240 and does not understand touch gestures. It does have the advantage of not needing an additional power supply.

Figure 2: The C-Berry display does not consume much power, but it delivers only limited resolution. ©Admatec

The Unicorn Hat [7] mini light display has 64 RGB LEDs set up in an 8x8 matrix. Each of the RGB LEDs can be controlled individually, allowing the Rasp Pi to display simple images, generate special lighting effects, or project a particular mood in a room. The manufacturer has issued a warning regarding the brightness of the LEDs. It is recommended that users avoid looking directly at the Unicorn Hat when the lights are turned on because of their extreme brightness. Users are also advised to use a diffuser to scatter or dim the light whenever possible.

The Unicorn Hat uses Pulse Width Modulation (PWM) hardware and GPIO pin 18. The Raspberry Pi should also be connected to a power supply that delivers 2A. The Unicorn Hat costs £24/$36.

Measure, Control, Regulate

Gertboard [8] is an extension that any user wanting to use the Raspberry Pi for measurements, control, or regulation should take a look at. Among other things, the board can be used as a control for motors, analog-to-digital (AD) and DA transformers, a freely programmable ATmega microcontroller, a pressure switch, and open collector outputs. The Gertboard can be connected directly to the GPIO pins with a flat ribbon cable. You can purchase one of these boards for about EUR50/$56.

The RasPiComm can be used to retrofit a series RS232 interface [9]. This adapter board gets plugged into the GPIO pins, and it offers I2C connections for things like sensors. It also offers a five-way joystick connection and an RS485 interface for attaching the control for stepper motors. The RasPiComm contains a real-time clock that runs on battery, even when the Rasp Pi is shut down; it costs $56. For the user who only needs an RS232 interface, the RS232 GPIO shield from LinkSprite is a good alternative with its $22 price tag [10]. See the "Everything at Once" box for more information.

Everything at Once

LinkSprite is an American company that offers the modular Linker Kit [15]. The starting point for a user of this kit is to attach a board called the Baseboard to the Raspberry Pi. The board contains several connections for plugging in modules for taking measurements and for display that are also produced by LinkSprite. A significant advantage to this system is that the user can purchase just the modules that are needed instead of a universal board stuffed full of functions.

Conrad Electronic sells the Baseboard and the modules for the Linker Kit [16]. Together with eight connections, the Baseboard costs around $22. Each module costs between $6 and $16.

The PiFace Clock is a battery-buffered real-time clock that costs about $10 [11]. The PiFace company also offers an extension that has two relays, four buttons, eight LEDs, eight digital inputs, and eight open collector outputs. This board costs around $25  [12].

Buy this article as PDF

Express-Checkout as PDF

Pages: 8

Price $2.95
(incl. VAT)

Buy Raspberry Pi Geek

Get it on Google Play

US / Canada

Get it on Google Play

UK / Australia

Related content

  • Exploring the new Raspberry Pi Model B+

    The new Raspberry Pi Model B+ is the biggest change to Raspberry Pi since the Model B Rev 2 upgrade two years ago. Find out what's new with the B+ and how it will affect your Rasp Pi adventures.

  • Using the Raspberry Pi as an AirPlay server

    AirPlay lets you send music from iTunes to AirPlay-capable receivers. Now you can use Shairport to retrofit a Rasp Pi and avoid the expense of purchasing an AirPlay receiver.

  • Math, Music, and Cat Toys

    Welcome to Raspberry Pi Geek – the first and only print magazine dedicated to the amazing Raspberry Pi mini-PC and the open hardware revolution. We ring in the new and old in this issue. (Actually, nothing is really very old with the Raspberry Pi, but we follow up on some previous themes, including a report on how it went for the wind-turbine-powered Raspberry Pi we described last time.)

  • Up close with the Banana Pi

    The Raspberry Pi has spawned a new generation of imitators. One of the top contenders is the Banana Pi.

  • Smells Like Maker Spirit

    The maker movement just keeps getting stronger, and open hardware and software are right in the middle, combining electronics, code, construction kits, and bits and pieces of whatever's in the spare parts bin to create something new or remake something old.