The Raspberry Pi has an impressive ability to drive a display device given its very modest power requirements and hardware specifications. While the default options for connecting a monitor to your RPi involve either an HDMI or RCA composite connection, the energetic community has experimented with a number of other options. Here are some other ways that you can connect a display to your Raspberry Pi, and many of them make for some great entry-level projects.
For many people in the hardware hacker community, the addition of an LCD to a project equals instant style points. The Raspberry Pi is no exception, and as such there are lots of places online that detail how to add an LCD to your Pi. The Adafruit LCD Pi plate is a particularly easy solution, allowing you to add a 16x2 character LCD directly onto the I2C pins on the Raspberry Pi. The display can then be used to show short messages, or act the primary interface, as it includes a keypad, allowing the Pi to function as a standalone LCD device.
Touchscreens have obviously become the interface of choice for mobile applications, and so it's little surprise that a number of kits have emerged for the highly portable Raspberry Pi. The Chalkboard Electronics touchscreen kit is a 10 inch LCD with touchscreen that a board for interfacing with the Raspberry Pi, allowing for a plug and play solution. The addition of a touchscreen to the Pi opens up a number of opportunities for learning about UI development in building increased touch functionality into the Raspberry Pi operating system.
The Raspberry Pi is a great candidate for powering an LED ticker device, and a number of projects have developed an interface between the Pi and the popular Betabrite LED ticker. Once the devices are connected the Raspberry Pi can pull information from a variety of sources including the internet to drive the display. A real time customizable stock ticker or twitter client are just a few of the possibilities for this project. While a traditional computer can provide this information, having this info available on a clear indoor/outdoor ticker can have a number of useful possibilities.
In a similar vein to the LED ticker, one Raspberry Pi enthusiast has created an LED cube that is powered by this undersized computer. Since the interface has been designed from scratch, along with the matrix of LEDs, this is a far more advanced project than the Betabrite solution, which relies on a comparatively standard interface. The finished product is an attractive programmed light show on the cube. However, with further work, one can see this project might have interesting possibilities as a way to easily visualize information using shapes or colors, or even play games.
Finally, an important display option for the Raspberry Pi is also the one typically used by default: the HDMI connection. That the Raspberry Pi can be displayed through an HDMI connection on a TV is impressive, it is even able to render at 1080p resolution, despite its underpowered hardware. This is important because it opens up the possibility of driving video application through the Raspberry Pi, and even using the Raspberry Pi as a media streaming device. In fact there are a number of projects that do exactly that. One of the bigger projects uses the popular XBMC software modified for the Pi to turn it into a very cheap, yet quite capable full-featured media center.