Hardware Reference
In-Depth Information
4
Hacking the Outdoors
Electronics outside, you say? Isn't that a bad idea? We do have a couple of water-
resistant suggestions (
Hack #39
and
Hack #40
). But we also have ideas for how to put
your Pi to use on your outdoor projects, from monitoring your garden (
Hack #38
) to
controlling your holiday lights (
Hack #45
).
Tell the Temperature Outside (Without
Going Out There)
HACK 37
The outside temperature is not a constant value; it fluctuates, and we
know you like to know what it is. Whether you're helping plants stay
healthy or just want to know how many layers of clothes to wear, this hack
can help!
Hack #05
shows that the Raspberry Pi measures the temperature of its BCM2835
system-on-chip, but this is different. In order to read the temperature near the Rasp-
berry Pi (or even nowhere near it), you'll need to connect a temperature sensor. While
Linux supports some USB thermometers, it is just as simple (and arguably more fun),
to wire up a simple temperature sensor to the GPIO on the Raspberry Pi.
This hack uses the Texas Instruments TMP102 I2C temperature sensor for the fol-
lowing reasons:
• It is very small. Smaller than a quarter. See
Figure 4-1
for proof.
• It is a digital sensor (this makes the wiring much easier and the results much more
accurate).
• Sparkfun sells it already
connected to a breakout board
.
• It is cheap (less than $6 USD at the time of this writing).
• It is accurate over a range of temperatures from -25°C and +85°C. (That's -13° to
185°F.)
