X10

• "old" technology from 1976
• Proprietary, controlled by X10 at www.x10.com
• Uses existing power lines to send signals to X10 modules
• Many vendors of X10 products exist e.g
  • Eon3 Home Automation (www.eon3.com.au)
• X10 has been called the "DOS of home networking" - primitive but will form a base level of home networks

Common modules

• Socket module - plug/screw a lightbulb into it
• Appliance module - plug any other electrical device into it e.g. toaster, TV
• Wall switch - replace existing wall switch
• Dimmer switch
• Universal module to control low voltage devices such as home watering systems
• More recently, the controlling company has added in USB, infrared, etc support

Adressing

• The protocol specification is at ftp://ftp.x10.com/pub/manuals/cm11a_protocol.txt
• X10 uses a bit level addressing scheme
• There are 16 "homes": 'A' to 'P'
• Within each home there are 16 devices: 1 to 16
• Each house and device is represented by a 4-bit code

  Housecode	Device Code	Binary Value
  A	1	0110
  B	2	1110
  C	3	0001
  D	4	1010
  ...	...	...

• Function codes are

  Function	Binary Value
  All Units Off	0000
  All Lights On	0001
  On	0010
  Off	0011
  Dim	0100
  Bright	0101
  All Lights Off	0110
  Extended Code	0111
  Hail Request	1000
  Hail Acknowledge	1001

Protocol format

• The PC communicates with an X10 interface through the serial port
• The serial port parameters are
  • Baud Rate: 4,800bps
  • Parity: None
  • Data Bits: 8
  • Stop Bits: 1
• Commands from the PC are of two forms
  • instruct a device to listen. Any number of devices can be told to listen
  • send a command to all listening devices
• The PC sends a header/code 2-byte pair
• The header byte sets
  • 5 bits for a parameter such as brightness
  • 1 bit always as 1
  • 1 bit to set function or address
  • 1 bit to set standard or extended data mode
• The code byte sets house+device or house+function code

Example

The PC could send

Communication from the network

• When the interface receives data from the power line it needs to tell the PC about it
• It asserts the serial line RI and then uploads upto 10 bytes of data, representing what has happened on the network
• The 10 bytes contain the function e.g. brightness, the type of data (address or function) plus the data, which could be an address value or function value
• Many devices will not send messages if they change state
• Note that this is an unreliable way of monitoring the network. Most PC appplications have to guess at the state of the devices based on the messages they have sent

Software

• Most X10 PC interfaces come with Windows s/w to control the interface
• A simple Linux system by Daniel B. Suthers is available from http://heyu.tanj.com/heyu/index.html
• A more complex Linux version is at http://wish.sourceforge.net/

Summary

• X10 is a proprietary format giving a simple level of control
• There are a number of X10 devices from different vendors conforming to this format
• It is a low-bandwith protocol
• There appears to be no addressing of security (you could turn your neighbours lights off?)
• It requires no additional infrastructure, using existing wiring