Making Things Talk

316 MAKING THINGS TALK

Between my officemate and me, we have

dozens of devices drawing power in our

office: two laptops, two monitors, four or

five lamps, a few hard drives, a soldering

iron, Ethernet hubs, speakers, and so

forth. Even when we’re not here, the room

is drawing a lot of power. What devices

are turned on at any given time depends

largely on which of us is here, and what

we’re doing. This project is a system to

reduce our power consumption, particu-

larly when we’re not there.

When either of us comes into the room,

all we have to do is throw our keys on a

side table by the door, and the room turns

on or off what we normally use. Each of us

has a key ring with an RFID-tag key fob.

The key table has an RFID reader in it, and

reads the presence or absence of the tags.

MATERIALS

» 1 solderless breadboard such as Digi-Key

(www.digikey.com) part number 438-1045-ND, or

Jameco (www.jameco.com) part number 20601.

For the photos in this example, I used an Arduino-

compatible Protoshield module from SparkFun,

part number DEV-07914.

» 1 Arduino module or other microcontroller

» RFID reader Either the RFID Reader Module from

Parallax, part number 28140; the ID Innovations ID-

12 from CoreRFID or SparkFun part number SEN-

08419; or the APSX RW-210 from Trossen Robotics.

» Two 2mm female header rows if you’re using the

ID12 reader, Samtec part number MMS-110-01-L-SV.

Samtec, like man ...