Thursday, May 20, 2010

Advanced Embedded Systems - Semester Project

Hi All,

The semester ends on a good note with a well done semester project. The project was to design a conceptual prototype of an "
RFID based personal home automation system." The system is basically designed to control electrical appliances found in homes depending on the RFID tags detected.

The Concept: The basic concept of this system was custom operations of appliances depending on the individual needs of the users using the appliance. For example, Person A living in a home likes the room temperature to be at 75 deg F, likes the room lighting to be dim and would like the home theater system to start as soon as he enters the room. The person A would have an RFID tag with him all the time in simple form such as a key-chain, a smart card or even a removable sticker attached to his apparel. The main door frame of the house is conceptualized to be a RFID tag reader. As soon as person A enters the house, the tag reader reads the unique tag and transfers it to a system (which can be a laptop computer or any custom embedded system). A program running on the laptop will read the RFID reader log-file and send the tag to a mote (Crossbow's mica2 mote) connected to the same laptop using a standard USB cable.

The mote connected to the laptop is the base station which broadcasts the tag-id to all the motes which are conceptualized to be connected to the electrical appliances. The appliances will work in a customary manner according to tag-ids being received by the motes i.e. in this scenario, the mote connected to the air conditioning system will set the thermostat at 75 deg F according to person A's needs. Likewise, every member of the house can carry a tag with the preference level set for every tag.

The setup: Texas Instruments TRF7960 EVM hardware module was used as a tag reader. The features include:
Support for ISO 15693 standard, An onboard 13.56 MHz loop antenna and interface, Communication with host software on a Windows based PC through a standard USB interface.
A laptop which runs Windows XP (to run the RFID tag-it software and TinyOS) and has cygwin installed. Cygwin is a software which runs on windows and creates a UNIX like operating system environment. TinyOS is installed on the laptop to program the motes and inject commands into the network.
Crossbow mica2 motes are used to control the appliance. To demonstrate the application, the debugging LED's on the moca2 motes were used as indicator of different tags. One of the motes was connected to the laptop to function as the base station. The base station was programmed with the TOSBase module. The remote motes were prorammed with the SimpleCmd module.


Working: A program (designed using C) runs in the cygwin environment which reads the log file created by the tag-it software. The program searches for the particular unique tag in tha log file. As soon as the tag is detected, it broadcasts it using the "BCastInject" java tool through the base station. Depending on the tag received, the red or the green LED's on each mote turns ON. If the tag is detected the second time (which would mean that the person has exited) the respective LED's toggle.

The future work would involve designing a control system for each appliances to interface the mote so that they can be controlled directly.


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