26-05-2012, 02:58 PM
Anti Theft System for Electronic Equipments using Inertial MEMS
Sensor and ZigBee
Abstract
As modern electronic goods such as computers, mobile phones, portable players,
laptops and palmtops are becoming smaller and more sophisticated, they can be more
easily targeted for theft in the home and business environment. Many present protection
systems are done with mechanical (mercury) switches which initiate an alarm when a
certain preset level of motion is detected. These units are bulkier and it cannot be easily
integrated with the existing compact electronic systems.
This project overcomes the drawbacks of present systems. It takes advantage of
the dramatic advances in micro machined semiconductor product technology and
employs a tri axis micro machined accelerometer integrated on a chip which is mounted
into the system to be protected. MEMS accelerometer can sense motion on all the 3 axes.
To lock the system, the user must keep the device in rest state (independent of
position and direction) and press the lock button. Firmware being executed on the
microcontroller captures the rest position of the system on all 3 axes (x, y and z) and
stores it in a non-volatile memory and enters into the lock state. It continuously translates
the acceleration detected and determines whether the movement/displacement conditions
have been exceeded on all 3 axes. Any movement in an unauthorized way initiates a
sequence of events
· Alert a control unit at a remote location through a zigbee wireless modem
· Disable further operation of the system
· Audible alert through a buzzer or siren.
The system remains in this state until the remote control unit transmits an
emergency password which must match the 10 digit device identification number stored
in the nonvolatile memory space.
Anti theft system is implemented for an innovative device that acts as city road
guiding equipment. The device aims at informing people about the city bus numbers for
the places they wish to go. A unique code number has been assigned to all the places in a
city. The user simply enters the two digit number, using the keypad, that represents the
destination place and our system, in response, provides the information of all the bus
numbers available for that particular destination. The database is stored in the external
memory chip. The entire system is based on the Master-Slave architecture of I2C
network. The I2C network consists of PIC microcontroller which acts as the bus master
and all other nodes viz. MEMS accelerometer, serial EEPROM memory, serial LCD
display acting as slave devices.