Hardware Reference
In-Depth Information
Add a Tiny Screen
HACK 57
Sometimes it's just not convenient to carry around a full-sized monitor.
Maybe you want to build a tiny, portable computer. There are screens for
you!
When we decided to start working on portable Raspberry Pi projects, we chose
Ada-
fruit's 2.5” NTSC/PAL display
,
partly for the quality and partly because it was one of
the few options at the time. It has RCA connections, 32 levels of backlight brightness
you can adjust with buttons, and a switch that changes it from portrait to landscape
display.
The one downside for connecting this piece to your Raspberry Pi is that it has a female
RCA jack, just like your Pi. There are male-male RCA connector pieces, which is what
we've used here to connect them, but that adds about an inch and a half of inflexible
metal bulk to your project.
OK, we lied. There's a second downside. The ribbon that connects the display to
the board in this little TFT setup is pretty fragile. Be extremely careful with it when
you're getting your project together, and take this into account when you decide
how to build it a housing, especially if it's a portable project.
Perhaps you've noticed that we like to tell you to do things that are generally consid-
ered a bad idea. (To some degree, that's the nature of a
hack
, isn't it?) Here's another
one. Officially, you can't power this TFT through the GPIO. It doesn't even make a lot
of sense to try if you read the description for the board, which states:
• Power with 6-15VDC only into onboard buck converter
• 80 mA power draw at 12 V, 150 mA at 6 V
Conveniently, we're not the kind of people who read instructions (or requirements, or
even good advice sometimes). And thus we didn't notice that at all before connecting
it to the GPIO in a prototype miniature game center. (If you'd like to do so, combine
this hack with
Hack #51
.)
And it worked. We wired the red to pin 2 (5 v) and the black one to pin 4 (ground), as
shown in
Figure 6-2
.
