Attention Creative Design Engineers:
Getting Connected To The Internet Can Earn You Cash.





Grand Prize

Internet Connectivity Category Winners

First Prize • Second Prize • Third Prize

Internet Application Category Winners

First Prize • Second Prize • Third Prize

 

INTERNET PIC 2000 CONTEST WINNERS

MAKING THE CONNECTION

FIRST PRIZE WINNER
PIC X10 WEB SERVER
by Edward Cheung

Edward Cheung
Mitchellville, MD
echeung@hst.nasa.gov

The home automation industry is dominated by a standard known as X10[1]. Devices that are compatible with this product line are sold by outlets such as Radio Shack and Sears making them widely available to the general public. These units communicate over the existing power line wiring to control all sorts of loads such as lamps and appliances. A simple powerline modem is also obtainable that will allow a computer to send and receive these commands. The PIC X10 Web Server combines a web server and an X10 controller. With this project, any user can control and monitor over the web the status of their home or office environment that has been equipped with X10 units.

Photo 1—The green board is the Ethernet card that plugs into the ISA connector on the custom PIC processor card and the powerline modem is in the background.

 

A significant difference from previous PIC based Web Servers [2] is the Ethernet interface, making this the first direct Internet connected PIC known to the author. This project is similar to the PicoWeb Server [3] except for several differences:

• A PIC16F877 instead of an ATMEL microcontroller is used.

• The maximum file size is not limited to one Ethernet packet (1400 bytes). This complicates software considerably as more of the TCP/IP stack needs to be implemented.

• The need for the 16 KB of external RAM is eliminated as all code fits in the PIC’s onboard resources.

One of the personal goals achieved in this project was to see if a web server could be written from scratch using only electronic documents from the web. The completed project is not only a fully functional Ethernet web server, but also handles the timing critical tasks of the X10 interface making it useful for home automation and control.

The PIC obtains its Ethernet interface via a standard NE2000-compatible Ethernet card. It is plugged into an ISA connector on the printed circuit board that holds the PIC. The PIC emulates a PC ISA interface to communicate with the Ethernet card.

After the X10 Web Server is connected to the local LAN, any user can communicate with the server by using the URL http://IP_ADDRESS, where "IP_ADDRESS" is the preselected IP Address of the web server. Photo 2 shows an example of the resultant display on the browser.

Photo 2—This page automatically reloads itself every 5 s to provide an up-to-date view of the status of the units. The user can click on commands to change the status of the units. The first column is the name of the unit, the second the address, the third the current state, and subsequent columns hold hyperlinks that cause that command to be sent.

 

The user can check the status of the units and can also click on the hyperlinks to send commands to control the loads (which will update their status). If any other controller sends a command to the load, its status is also automatically updated in the home control panel.

The control panel can be reconfigured if the user clicks on the "Config" button at the bottom of the main control panel. The resultant display is shown in Photo 3.

Photo 3—The configuration panel allows the user to add or delete units with these two forms. Up to 16 load controllers can be accommodated on the home control panel.

 

To add a unit, the user simply enters the X10 address (in this example "A1") and its name ("Room") and then clicks "Add." The user is then returned to the main auto-loading home control panel with the new unit added (its status will be displayed as "?"). Similarly, clicking on "Delete" after entering a unit number causes that unit to be deleted from the control panel. The names and the status of up to 16 units are preserved in the PIC’s nonvolatile EEPROM.

This powerful and compact web server should be a useful addition to any environment requiring the capability to send and receive X10 commands without needing the installation of any unusual hardware or software.

REFERENCES

[1] The X10 company, http://www.x10.com

[2] Serial-line PIC web server, http://www-ccs.cs.umass.edu/~shri/iPic.html

[3] PicoWeb Server, http://www.picoweb.net