TABLE OF CONTENTS In the late 1970's, a small Scottish company, Pico Electronics, joined with BSR, famed for its high fidelity turntables, to produce inexpensive home automation equipment. Pico Electronics' deceptively simple idea was to use a home's power wiring to communicate from a controller to small remote control modules. The result was the BSR System X10, originally sold at Radio Shack and Sears. BSR is no longer in business, but its X-10 business is carried on by X10 USA. (The Company's name is "X10" but the technology is identified as "X-10.") Many manufacturers have licensed X-10 technology, and a wide variety of remote switches, dimmers and other devices are available.
MBasic's xin and Xout functions provide built-in support for both transmitting and receiving X-10 signals. This chapter also covers nontraditional use of X-10 technology, such as telemetering temperature readings.
The technology behind X-10 is to send brief bursts of 120 KHz signals over the power lines, timing the bursts to coincide with the 60 Hz power line zero-voltage crossings. At the zero voltage point the power line noise level is at a minimum and the 120 KHz signal has the best chance to be received by a remote control module. We'll go through X-10's protocol by starting at the top and working down to the bit level.
At the highest level, X-10 messages are comprised of three elements:
| House Code | Unit Code | Function Code |
Let's look at each element in more detail.
House...
