By Priyanka Botny SrinathBy Priyanka Botny Srinath

Need and Goal

Need•Electronically controlled lock and key systems are quite expensive•Security has been a concern for main doors and carsGoal•To provide a secure, low cost door lock system•To provide a foolproof, easy to use, electronically controlled security system

Lock Side Block Diagram

Key Side Block Diagram

Arduino Uno• ATmega328P

microcontroller• 16MHz Crystal Oscillator• USB connection• ATmega8U2 for USB-to-

TTL conversion• 14 Digital I/O Pins• Input Voltage: 7-12V• Power Supply: USB or

External

Arduino Uno Front

Arduino Uno Rear

ATmega328P

• 8-bit Microcontroller• 28-pin PDIP• Up to 20MHz @ 1.8 - 5.5V• Advanced RISC Architecture• 32KB Flash Memory• 2KB SRAM• 1KB EEPROM

Xbee (ZigBee) Module

• Range up to 30m• DSSS (Direct Sequence

Spread Spectrum)• Frequency of operation – ISM

2.4GHz• Uses serial UART interface to

communicate

XBee Module

IR Based Obstacle Detection• Sensitivity up to 30 cm

(Adjustable)• Operating Voltage – 5V• Adjustable Range with

Potentiometer• Logic Output – Binary

1/0 (5/0V)

Lock Mechanism• Solenoid coil• 7.5V, 2.5A• Uses magnetic fields to

operate on the steel rod

Lock Side Schematic Diagram

Key Side Schematic Diagram

Advantages

• Better security compared to conventional electronic locking systems

• Easy to use. Shut it and forget it!• Low maintenance cost• Cannot be easily duplicated• Alarm system inbuilt• NRE cost of the product is Rs. 500 ($10)

Limitation

• Continuous power consumption• Easy to lock oneself out (if the key is left

inside)

Applications

• Homes security locking systems• Banks, Police Stations and high security

buildings where single entry is permitted• Automobile Lock System at low cost

Further Enhancements

• RFID (Radio Frequency Identification) usage on the key side

• WiTricity – Wireless Electricity Transfer to reduce power consumption

• Integration with portable devices like mobile phones

• GPS for key tracking• Biometrics and Touch Screen Interfaces