Synopsis on Android-Powered Access Control via Bluetooth

Bachelors of TechnologyElectronics and CommunicationDepartment of Electronics and CommunicationTeam Members:

Faculty Involved:

1. Eshant Singh

Mr. Danish Quamar2. Sangeeta Singh chauhan3. Ashish Singh Bisht 4. Varun Panjratan Introduction:Lately, there has been much talk of Android operating system, which is a touch-o based interface for mobile devices like smart phones and tablets interfacing Android powered devices using Bluetooth to control household appliances like fans lights and AC is becoming popular amongst students and hobbyists. Learning and playing with Android based devices is not only interesting but useful as well.

Presented here is a password based access control system using your android device you can open a gate or door only when you send a valid password from your Android phone.

System requirements are Android based Smartphone, Bluetooth module, Frredunio board, Electric Strike lock YS 130, Arduino 1.0.2 and Bluetooth SPP.

Access Control:

In the fields ofphysical securityandinformation security,access controlis the selective restriction of access to a place or otherresource.Locksandlogin credentialsare two analogous mechanisms of access control.Physical Security:Geographical access control may be enforced by personnel (e.g.,border guard,bouncer,ticketchecker), or with a device such as aturnstile. There may befencesto avoid circumventing this access control. An alternative of access control in the strict sense (physically controlling access itself) is a system of checking authorized presence, see e.g.Ticket controller (transportation). A variant is exit control, e.g. of a shop (checkout) or a country.

The term access control refers to the practice of restricting entrance to a property, a building, or a room toauthorizedpersons. Physical access control can be achieved by a human (a guard, bouncer, or receptionist), through mechanical means such as locks and keys, or through technological means such as access control systems like themantrap. Within these environments, physical key management may also be employed as a means of further managing and monitoring access to mechanically keyed areas or access to certain small assets.

Physical access control is a matter of who, where, and when. An access control system determines who is allowed to enter or exit, where they are allowed to exit or enter, and when they are allowed to enter or exit. Historically, this was partially accomplished through keys and locks. When a door is locked, only someone with a key can enter through the door, depending on how the lock is configured. Mechanical locks and keys do not allow restriction of the key holder to specific times or dates. Mechanical locks and keys do not provide records of the key used on any specific door, and the keys can be easily copied or transferred to an unauthorized person. When a mechanical key is lost or the key holder is no longer authorized to use the protected area, the locks must be re-keyed.

Electronic access control uses computers to solve the limitations of mechanical locks and keys. A wide range ofcredentialscan be used to replace mechanical keys. The electronic access control system grants access based on the credential presented. When access is granted, the door is unlocked for a predetermined time and the transaction is recorded. When access is refused, the door remains locked and the attempted access is recorded. The system will also monitor the door and alarm if the door is forced open or held open too long after being unlocked.

Access Control System Operation:

When a credential is presented to a reader, the reader sends the credentials information, usually a number, to a control panel, a highly reliable processor. The control panel compares the credential's number to an access control list, grants or denies the presented request, and sends a transaction log to a database. When access is denied based on the access control list, the door remains locked. If there is a match between the credential and the access control list, the control panel operates a relay that in turn unlocks the door. The control panel also ignores a door open signal to prevent an alarm. Often the reader provides feedback, such as a flashing red LED for an access denied and a flashing green LED for an access granted.

The above description illustrates a single factor transaction. Credentials can be passed around, thus subverting the access control list. For example, Alice has access rights to theserver room, but Bob does not. Alice either gives Bob her credential, or Bob takes it; he now has access to the server room. To prevent this,two-factor authenticationcan be used. In a two factor transaction, the presented credential and a second factor are needed for access to be granted; another factor can be a PIN, a second credential, operator intervention, or a biometric input.

There are three types (factors) of authenticating information: something the user has, such as smart card or akey fob something the user knows, e.g. a password, pass-phrase or PIN

something the user is, such as fingerprint, verified by biometric measurement

Passwords are a common means of verifying a user's identity before access is given to information systems. In addition, a fourth factor of authentication is now recognized: someone you know, whereby another person who knows you can provide a human element of authentication in situations where systems have been set up to allow for such scenarios. For example, a user may have their password, but have forgotten their smart card. In such a scenario, if the user is known to designated cohorts, the cohorts may provide their smart card and password, in combination with the extant factor of the user in question, and thus provide two factors for the user with the missing credential, giving three factors overall to allow access.

Block Diagram:

Circuit and Working:Block diagram for android-powered access via Bluetooth is shown in the fig1. The system composed of a transmitter and a receiver. The transmitter is nothing but your Android Smartphone or tablet with Bluetooth enabled .The receiver consist of power supplies AVR microcontroller, Bluetooth module, solenoid-based electric lock.

You can transmit control signal from your android device to the receiver to lock or unlock the gate fitted with an electric door locking system.

The complete receiver circuit is shown in fig 2.

Power supply:

The circuit requires 12V, 5V and 3.3V DC supplies for various sections. 12V supply is derived from a 230V AC primary to 15V, 500mA secondary transformer. The output from bridge rectifier module BR1 is filtered by capacitor C1 and then fed to 7812 regulator. 12V output from 7812 regulator IC is given to 7805 regulator IC and electric lock and its driver section. 5V from the output of 7805 IC is given to the AVR microcontroller. Zenre diode ZD1 (3.3V) is used to obtain 3.3V supply for the bluetooth module. The glowing of LED1 indicates the presence of power in the circuit.

AVR Microcontroller:AVR microcontroller is the heart of the system; the program in the microcontroller processes the received signal and then locks or unlocks the electric lock.

The Atmel ATmega 328 is a low power CMOS 8-bit microcontroller based on the AVR enhanced RISC architecture. By combining an 8-bit RISC CPU with in-system self-programmable flash on a monolithic chip the ATmega 328 is a powerful microcontroller that provides a highly flexible and cost effective solution to many embedded control applications. It has a rich instruction set with 32 general purpose working registers.

Some of its features are 32KB of in system programmable Flash with read while write capabilities, 1KB EE PROM, 2KB SRAM, 23 general purpose input/ output(I/O) lines, 3 flexible timers / counters with compare modes, internal and external interrupts, a serial programmable USART, a byte-oriented two wire serial interface, an SPI serial port, a 6/8-channel 10-bit analogue to digital converter (ADC), a programmable watchdog timer with internal oscillator, and five softwares- selectable power saving modes.

The on-chip ISP Flash allows the program memory to be reprogrammed in-system through an SPI serial interface, by a conventional non-volatile memory programmer or an on-chip boot program running on the AVR core. The boot program can use any interface to download the application program in the application Flash memory. Software in the boot Flash section continues to run while the application Flash section is updated, providing true read- while- write operation.

The AVR communicates with the bluetooth module through its TXD(transmit) and RXD(receive) pins. The signals received from the bluetooth module is processed by the software in the microcontroller. The control output signal is available at its pin 15.

Bluetooth Module:

We have used a 4-pin, HC-05 Bluetooth module in this project. It is an easy-to-use Bluetooth serial port protocol (SPP) module, designed for transparent wireless serial connection setup.

Serial port Bluetooth module is fully qualified for Bluetooth V2.0+EDR (enhanced data rate) 3Mbps modulation complete 2.4GHz radio transceiver and baseband. It is a low power module that operates of 1.8V to 3.6V. Its default values are: baud rate- 38,400, data bits- 8, stop bit- 1, parity- no,. It supports baud rates of 9600, 19,200, 38,400, 57,600, 115,200, 230,400 and 460,800. By default the auto-pairing pin code is set as 0000 and password as 1234. The HC-05 Bluetooth module is shown in fig 3.

Care should be taken while handling this module you need to extend four connections to the circuit. These connections are wires for TXD, RXD, Vcc and GND pins, TXD pins of the module should be connected to TXD pin of the microcontroller. Vcc pin is connected to 3.3V and GND pin is connected to the common ground rail of the circuit.

Electric Strike:

Electric strike fig. 4 is an access control device used to lock and release doors. Its applications can be found in all areas ranging from single door to large PC-based systems.

Electric strike is installed in or on the door frame and work in conjunction with mechanical doors locks. All strikes basically works on the principal of electronically controlling the temporary free movement of the jaw (striker) allowing door opening movement without manual retraction of the latch bolt a typical electronic door locking system is shown in fig. 5.

Electric strikes are generally available in two configurations:

1. Fail-Secure: In this configuration, applying electric current to the strike causes it to open. The strike would remain clocked in the event of power faliure, but typically provision is made for the knob to open the door or provide alternative solution.

2. Fail-safe: In this configuration, applying electric current to the strike causes it to lock. It operates the same way as a magnetic lock would. If there is a power failure, the door opens merely by being pushed or pulled.

Fail-secure configuration is used in the project. This is the most common type available in the market. It is very simple mechanically and electrically. It uses a solenoid to pull back a locking piece into the strike to allow opening of the door. If the solenoid doesnt pull back the locking piece, the strike wont open, creating a Fail-safe situation. Normal operation of the doorknob or push bar from the system will still let the people out in this situation.

There are various makes and models that use different voltages, both AC and DC. The electric strike used here operates off 12V DC. The whole system is equipped with a buzzer and a LED indicator to give the user audio and visual indication of door opening. In this project we have used a 12V battery as a backup source during power failure.

PCB Design and Final PCB:

Test points:

Test PointsDetails

TP00V,GND

TP112V

TP25V

TP33.3V

TP4Low when S1 is pressed

TP5High pulses when password entered.

Parts List:

Semiconductors

IC1ATmega 328 microcontroller

IC27812, 12V regulator

IC37805, 5V regulator

T1MPS2222 npn transistor

BR11A bridge rectifier module

LED1, LED25mm LED

D11N4007 rectifier diode

ZD13.3V zener diode

BluetoothHC-05 Bluetooth module

Resistors (all watt, +/- 5% carbon):

R1680 ohm

R2100 ohm

R310 K-ohm

R4,R51 K-ohm

Capacitors:

C11000 uF, 35V electrolytic

C2, C30.1 uF ceramic disc

C410 uF, 16V electrolytic

C5,C622 pF, ceramic disc

Miscellaneous:

X1230V AC primary to 15V DC,

500 mA secondary transformer.

PZ1Piezobuzzer

Xtal16MHz crystal oscillator

S1Push to on switch

S2On/Off switch

CON12-pin, 3.5mm connector for the electric lock

CON24-pin berg strip connector for Bluetooth

12V electric strike lock YS 130

BATT.112V, 7 Ah battery.

References:

Electronics for you July 2013 Access control - Wikipedia, the free encyclopedia.htm www.EFYmag.com Images gathered from magazine (Electronics For You) itself.