Appliance Control: Making Things Do Stuff - Smart Home Automation with Linux and Raspberry Pi - page 5

mischief. The second is that by switching away from the defaults, you can be sure that the system was successfully
reprogrammed and is not working temporarily by a happy coincidence.
Producing assignments for the unit codes is a matter for your own judgment, but you cannot go far wrong
by creating a pattern . I began by numbering my devices at 2 and worked around the rooms in my house in a
counterclockwise order, starting upstairs and ending in the kitchen. I assumed two devices per room. My reasoning
and thought processes were as follows:

u Start at 2 because 1 is used by the RF-to-X10 gateway.

u Two devices per room means each room starts at 2, 4, 6, 8, and so on, which is easy to

remember.

u The only time I need to know the numbers by heart is when fumbling with the remote in

the dark. This is when I'm in bed looking for a light switch. Because the master bedroom is
upstairs, I start counting upstairs. And when lying in bed, I'm facing the rest of the house,
with the second bedroom directly in front of me, and the third to its left, which makes a
counterclockwise motion more natural.

u If the split between upstairs and downstairs hadn't occurred on unit code 8, I would have left a

gap so that it did.

u I split the lounge/dining room into two logical rooms, even though it's one space. This means I can

have up to four devices in the one space, which is likely to happen with larger open-plan areas.

u The kitchen is more likely to gain devices over time, so I kept that last in the list.

If you browse the selection of controllers available, you will notice that most have a selector switch that reassigns
the buttons from 1-4 to 5-8, for example, or from 1-8 to 9-16. An alternate approach is to have the first bank (1-4, say)
controlling only the lamps in the house, with the second (5-8) being used to control the appliances in the equivalent
room, making it switch between “lamps and appliance” rather than “upstairs and downstairs.” This ensures that
although the first bank is selected, it's impossible to accidentally turn off an appliance when you mean to control the
lights, and vice versa.
The final consideration concerns the physical size of the controller modules you plan on using, as many support
only eight devices. If your most convenient numbering system happens to use devices 9-16, then you will either have
to rethink your pattern or buy only larger controllers.

Using Multiple House Codes
It is possible to have two or more house codes within a single property, bringing the total number of household
devices up to a maximum 256. That's enough for the largest of mansions! The only consideration with such setups is
that a control message such as “all lights off ” can be applied only to a single house code. For computer-based control,
you can easily adapt the software to send two (or more) messages of the “all units off ” variety, which affect all devices
on the specified house code. However, if you've elected to use only stand-alone remote controls, such as the desktop
controllers you will learn about later in this chapter, this can require some fiddling as you switch off each house code
in turn. In this case, you would probably want to split up the house codes into the first floor, second floor, and so on,
and have a separate controller for each floor.