X10 Home Automation Project

X-10 is a communication protocol designed for sending signals over 120 VAC wiring. X-10 uses 120 kHz bursts timed with the power line zero-crossings to represent digital information. X10 components send signals through your home electrical wiring. There are 16 house codes and 16 unit numbers per house code available on your network for a total of 256 addresses. You can control multiple devices by setting them the same house code.

X10 plug in modules are now commonly used in the area of security, lighting, control of TV, motion detectors and other applications. It should be noted if there is no filter at the house breaker box, signals can pass from one house to anotherand cause odd behavior. If you have problems with a device on a given house and unit code, experiment with other codes and see if the problem goes away.

X-10 transmissions are synchronized with the zero-crossings on the AC power line. By monitoring for the zero-crossings, X-10 devices know when to transmit or receive X-10 information. A binary ‘1’ is represented by a 1 ms long burst of 120 kHz,near the zero-crossing point of the AC. A binary zero is represented by the lack of the 120 kHz burst. The timing diagramis as shown below.

This application note discusses the implementation of X-10 on a PICmicro MCU to create a home controller that can both send and receive X-10 signals. The reader may implement the home controller as is, or adapt the circuits and firmware to other applications. A library of X-10 functions is provided to facilitate development of other X-10 applicationsusing PICmicro microcontrollers.

It allows the user to program on and off times for up to sixteen devices, using a 2 x 16 liquid crystal display and five push buttons. A built-in light sensor can be used to turn on lights at dusk, and turn them off at The home controller isdesigned to facilitate experimentation with home automation using the PIC16F877A.

It will be a good project for final year students to embark on and hence gain a considerable experience in X10 wirelesstechnology.

The application note of X10 Home Automation Project and its source codes can be downloaded from Microchip website.

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