Hardware Reference
In-Depth Information
This “house state” information could be extended to switch on security lights or redirect personal e-mails to
a work account, for example. To connect the Arduino output to the rest of the system, you will either need to use a
networking shield (either wired or wireless, depending your connection points) or need a local PC with one. The
advantage of a PC (such as a Fit-PC2, notebook, or similarly small machine) is that it can be reused as a display and
control panel. In this example, having a panel by the door displaying the tasks for the day and printing reminders
about the weather can provide a suitable excuse for the extra expense.
The code can be further expanded by using personal knowledge of the habits of yourself, and your family.
Consider, for example, the act of leaving your house and returning 10 seconds later to collect your gloves. On the one
hand (no pun intended), you could add a warning for lower temperatures to the speech synthesize module. On the
other, you could determine that anyone activating the pressure mat within 20 seconds is returning home (and not
someone else leaving it) and so ignore the usual messages.
Furthermore, you could extend this period of grace allowing you to get to the car, only to realize you've forgotten
your keys. At this point, you could automatically trigger an AlertMe device, which, when attached to the key, makes a
beeping noise so you can easily find it when the pressure mat detects that you have returned.
N
With minor modifications, you could employ two pressure mats (one inside and one outside) to more correctly
determine the direction of travel.
Note
Depending on the type of pressure mat used, you could also place one under a rug by the cat flap, as your pet's
weight is normally enough to trigger it. This would allow you to interface it with a LEGO robot that could then feed the
cat when they returned from their customary wander.
N
Caution
Most pressure mats cannot be cut to size because of their internal electronics.
Example: The Arduino Dictaphone
Most people make notes on the back of train tickets and shopping lists because the effort to switch on a computer or
find the phone's notepad application is too much. By combining the interface-less environment of an Arduino and the
audio functionality of a monitor-less PC, you can create a very simple voice recorder.
You start with the basic switch circuit, but you then replicate it three times—once for each of the record, play,
and erase buttons, as shown in Figure
2-7
.
+ve
R1
R2
R3
Pin 2
Pin 3
Pin 4
Figure 2-7.
Using three switches and inputs to control a voice recorder
Search WWH ::
Custom Search