Raspberry Pi - Smart Home Automation with Linux and Raspberry Pi - page 277

Photo Frames
The low cost of the Raspberry Pi has also meant that manufacturers of other home gadgets have had to up their game,
and bring down prices. A good quality digital photo frame used to be very expensive. Now, with just a Raspberry Pi
and a cheap display, you can better the best products on the market, providing a slideshow with images, videos, and
sound clips.
From the software point of view, this couldn't be easier. You could even use a standard screen-saver, or the
slideshow functionality of OpenElec or XBMC. If you're avoiding the web-based solution (and unless you want the
additional cost of adding a wireless board, or running Ethernet cable, there's no reason to connect this to the network)
there are a multitude of other solutions out there-eog ( https://help.gnome.org/users/eog/stable ), gthumb
( http://gthumb.sourceforge.net/home.html ), a kiosk system ( https://github.com/csldevices/sweb ) or fbi.
The latter uses the frame buffer device, so you don't need a full desktop install, which can be helpful in reducing the
boot time and footprint of your system.
By running the photo frame through software, instead of firmware, means that you can upgrade the system easier
to incorporate the changes for daylight savings hours, show the weather, or render the days schedule periodically
during the morning time, or to add alarms or messages sent from Node0 (as detailed in Chapter 7) to multiple
photo frames in the house. You can also more easily adapt the images that are shown, maybe to introduce images of
Christmas past in the month of December, or to add more of the family when you know they're coming to stay, and
remove them shortly afterward!
Weather Stations
You could also consider building, or enhancing, a weather station. Most come in two varieties—the cheap versions
that might report the temperature, wind speed, and chill factor, for example, but provide no means of exporting that
data outside of the device. The expensive versions provide a wireless or USB component for data export. However,
the difference in cost usually exceeds that of a Raspberry Pi, so it makes an interesting project to hack your own.
The specifics of each hack depend on the weather station itself. You can either trap the messages made by the
device ( http://hackaday.com/2011/09/06/lacross-weather-station-wireless-data-acquisition ) and reverse
engineer the protocol, or reappropriate the sensors and feed the results directly to the GPIO.
If you intend to study the protocol, buy a weather unit that has a separate outdoor sensor. In this way, the
protocol will have a definite end point, which makes it easier to engineer. (None of the ones I've seen encrypt the
weather data!)
The idea of buying a complete unit, only to cannibalize it for parts, might seem wasteful, but it is often cheaper to
do this, than it is to buy the sensors alone! Plus it's usually easier to find product specifications for the sensors, than it
is to find a description of the protocol. To this end, I would recommend looking for a project that's already happened
in this space (such as the Hack-A-Day example) and buy an identical device.
One such is Pywws, by Jim Easterbook. This Python program reads information from a Maplin USB weather
station and his project is documented http://www.weather.dragontail.co.uk/index.php?page=station_setup .
From here, the data can be graphed, analysed, and presented on a web page. The interest factor is replaced by the
utility function when you consider adapting your thermostat to reflect the temperature, especially when returning
from holiday.
Raspberry Pi as a USB Host
Looking at USB devices that need powerful drivers to operate, you could turn an old printer into a modern networked
printer with a Raspberry Pi by simply connecting one to the network and installing a CUPS server on it. This is a
standard package and prepared thus:
sudo apt-get install cups
sudo usermod -a -G lpadmin <your_user_name>