Hardware Reference
In-Depth Information
Make a Morse code program (medium)
If you make a sound file for “dot,” another for “dash,” and a third as a “gap,” you
should be able to play them in the right order to send Morse code.
Make a wireless network (hard)
As an extension of the Morse code idea, see if you can send any information (for
example, an image file) via noises on the radio, and make a decoder program on
your computer that can recognize the noises through a microphone and convert
it to a file again. You now have a crude wireless network link and radio-modem
that you have made entirely yourself!
—
Oliver Mattos and Oskar Weigl
Control the Pi via Touchscreen
HACK 50
While the Raspberry Pi has native hardware support for two types of vid-
eo output (HDMI and composite video), there are times where it would
be helpful to be able to use it with a touchscreen monitor, such as those
used for both display and input in tablet computers.
The Raspberry Pi Model B contains a Display Serial Interface (DSI) connector, which
is a 15-way, flat flex connector labeled S2 next to the Raspberry Pi logo on the board.
DSI is sometimes used to connect touchscreens in small-form-factor devices such as
smartphones. Sadly, adding a touchscreen to your Pi is not as simple as disassembling
an abandoned smartphone and reconnecting the screen to the DSI connector.
The GPU firmware that enables the native video output needs code to explicitly sup-
port any device connected to the DSI port. Since this firmware is not open source, it
is not currently possible to add support for any DSI-connected screens, nor are there
any known devices that the GPU firmware supports on the DSI connector. It is widely
expected that, at some point, the Raspberry Pi Foundation will release official periph-
erals that can connect to the DSI connector, which will make this a much simpler task
(assuming that one of those peripherals is a touchscreen). Until that point, however,
we'll just have to hack around it.
Choosing a Touchscreen
The first step is to figure out which touchscreen to connect to the Raspberry Pi. There
are quite a few touchscreen devices on the market, but the majority of them are ex-
tremely expensive, and the Linux support for them is haphazard at best. We chose the
Mimo 720 touchscreen because it is small (7” x 5.25” x 1”), light (less than a pound),
USB-driven, mountable with a bracket, and relatively inexpensive (MSRP $199 USD,
but it is regularly on sale around $129).
