2. Abstract
The Magnetic Door lock is a simple locking device that consists of a magnetic lock and armature plate
with no moving parts and it purely works due to the magnetic field. Therefore the magnetic lock is truly
fail-safe (Power to lock). Thus, the magnetic lock is met with both security and fire safety requirements
and is available for emergency exit doors. While the magnetic door lock might be quite a simplistic
locking device, but the efficiency of the locking gadget can certainly not be denied. The purpose of this
paper is to design Magnetic Door Lock employing Arduino Technology. Magnetic lock or mag lock uses
an electrical current to produce a magnetic force. When a current is passed through the coil, the magnet
lock becomes magnetized. The door will be securely bonded when the electromagnet is energized
holding against the armature plate. Access control systems are operated by peripheral device (ie.
keypad reader here ) to identify the user whether access is permitted or not. The power will be
automatically turned off by the user and gains access through a reader. The objective of the work
undertaken in this paper is to sense the correctness of a secret code using the Arduino technology.
3. I.INTRODUCTION II.DESCRIPTION ABOUT THE
THIS section gives a brief introduction about the work,
MICROCONTROLLER
which describes all the components namely Magnetic
This section gives a brief idea about the
Door Lock, Arudino platform, Atmeg168. Followed by
design of Magnetic Door Lock by Arudino ATMEGA168 microcontroller its core features,
Technology. block diagram, pin diagram and its description.
Door locks are certainly considered to be the basic A. INTRODUCTION
modes of the everyday household door and Circumstances that we find ourselves today in the
keeping this fact in mind, door locks hold an field of microcontrollers had their beginnings in
immense importance for the protection of doors. the development of technology of integrated
While the magnetic door lock might be quite a circuits. This development had made it possible to
simplistic locking device, but the efficiency of the store hundreds of thousands of transistors into one
locking gadget can certainly not be denied. chip. That was a prerequisite for production of
Magnetic Door Lock employing Arduino microcontrollers, and adding external peripherals
Technology. The main aim of the work such as memory, input-output lines, timers and
undertaken in this paper is to sense the correctness other made the first computers. Further increasing
of a secret code using the Arduino technology. of the volume of the package resulted in creation
When the correct code is entered through keypad, of integrated circuits. These integrated circuits
it lights a green LED in addition to operating a contained both processor and peripherals. That is
small solenoid which when powered, will strongly how the first chip containing a microcomputer, or
attract the metal slug in its center, pulling it into what would later be known as a microcontroller
place, when the power is removed, it is free to came out .
move.
B. MICROCONTROLLER VERSUS
Arduino is an open-source electronics prototyping MICROPROCESSORS
platform based on flexible, easy-to-use hardware Microcontroller differs from a microprocessor in many
and software. Arduino can sense the environment ways. First and the most important is its
by receiving input from a variety of sensors and functionality. In order for a microprocessor to be
can affect its surroundings by controlling lights, used, other components such as memory, or
motors, and other actuators. The microcontroller components for receiving and sending data must
on the board is programmed using the Arduino be added to it. In sort that means that
programming language (based on Wiring) and the microprocessor is the very heart of the computer.
Arduino development environment (based On the other and , microcontroller is designed to
on Processing). Arduino projects can be stand- be all of that in one. No other external
alone or they can communicate with software components are needed for its application because
running on a computer (e.g. Flash, all necessary peripherals are already built in to it.
Processing, MaxMSP). Thus, we save the time and space needed to
Arduino is a small microcontroller board with a construct devices.
USB plug to connect to your computer and a
number of connection sockets that can be wired C. ATMEL ATMEGA168
up to external electronics, such as motors, relays,
MICROCONTROLLER
light sensors, laser diodes, loudspeakers,
Overview:ATmega168 is widely used because it
microphones, etc. They can either be powered
supports wide range of system development tools
through the USB connection from the computer or
such as C Compliers, Macro assemblers, Program
from a 9V battery. They can be controlled from
Debugger/Simulators, In-circuit Emulators and
the computer or programmed by the computer and
Evaluation Kits . Its features includes: 23 general
then disconnected and allowed to work
purpose I/O lines, 32 general purpose working
independently. Since the Arduino is an open-
registers, three flexible timer/counters with
source hardware design,anyone is free to take the
compare/capture/PWM mode, a SPI serial port,
designs and create their own clones of the
16K bytes of in-system programmable Flash with
Arduino and sell them, so the market for the
Read-while-Write capabilities. 512 bytes of
boards is competitive.
EEPROM and 1K bytes SRAM. In Idle mode
4. CPU stops working while allowing the SRAM, channel 10-bit ADC, a programmable watchdog
timers/counters, USART, SPI port and interrupt timer with internal oscillator .
system to continue functioning. It also has 6
Description: The device is manufactured using through an SPI serial interface, by a conventional
Atmel’s high-density non-volatile memory non-volatile memory programmer, or by an on
technology.“The on-chip ISP flash allows the chip boot program running the AVR core”.
program memory to be reprogrammed in-system
Depending on the clock selection fuse settings,
PB6 can be used as input to the inverting
oscillator amplifier and input to the internal clock
operating circuit Depending on the clock selection
fuse settings, PB7 can be used as output from
inverting oscillating amplifier
PORT C (PC5:0)
Port C is a 7-bit bi-directional I/O port
with internal pull-up resistors. As inputs, Port C
pins that are externally pulled low will source
current if the pull-up resistors are activated
PC6/RESET If the RSTDISBL register is
programmed, PC6 is used as I/O pin. Behavior of
PC6 is different from other Port C pins. If
RSTDISBL is not programmed, PC6 can be used
as a Reset input. A low level on this pin for longer
than the minimum pulse length will generate a
reset even without the clock signal. Shorter pulses
are not guaranteed to generate a Reset
PORT D (PD7:0)
Port D is an 8-bit bi-directional I/O port
with internal pull-up resistors. As inputs, Port C
pins that are externally pulled low will source
current if the pull-up resistors are activated. The
Port D pins become tri-stated if the reset condition
become active, even if the clock is running .
PIN Description: AVCC
AVCC is the supply pin for the A/D
VCC Convertor, PC[5:0]. It should be externally
Digital supply voltage. connected to VCC, even if the ADC is not used. If
GND the ADC is used it should be connected to VCC
Ground voltage for the microcontroller through low pass filter
chip. AREF
PORT B (PB7:0) AREF is an analog reference pin for the
Port B is an 8-bit bi-directional I/O Port A/D convertor. XTAL1It is an input to the
with internal pull-up resistors. As Inputs, Port B inverting oscillator amplifier and the internal
pins that are externally pulled low will source clock circuit [2]. XTAL2It is an output pin from
current if the pull-up resistors are activated . the inverting oscillator amplifier.
5. Oscillator Characteristics:
As shown in Figure , XTAL1 is input and
XTAL2 is output of an inverting amplifier that
can be configured for use as an on-chip oscillator.
To use external oscillator as clock source, XTAL2
should be left unconnected while XTAL1 is
driven.
Quartz crystal or ceramic resonator can be used as
oscillator.
Block Diagram ATmega168 CCP Modules
Figure below shows the block diagram of the Each CCP (Capture/Compare/PWM) module
ATMEL ATmega168 microcontroller. The AVR contains a 16-bit register which can be operate as
core has 32 general-purpose registers. All these 16-bit capture register, as a 16-bit compare
registers are directly connected to the Arithmetic register or as a 16-bit PWM master/slave duty
Logic Unit (ALU), allowing two independent cycle register. The CCP modules are identical in
registers to be accessed in 20 one single operation, with the exception of the operation of
instruction executed in one clock cycle. The the special event trigger .Most registers and bit
resulting architecture is code efficient. The device references for this IC are written in general form.
is manufactured using Atmel’s high-density non- For example, a lower case “n” replaces the
volatile memory technology. Timer/Counter number, and a lower case “x”
replaces the output compare unit channel. When
these registers or bits are defined in a program,
they are declared as TCNT2 for accessing
Timer/Counter2 counter value and so on. Figure
below shows a block diagram for the 16-bit
Timer/Counter
6. • Arduino can be used to develop interactive
objects, taking inputs from a variety of
Registers
switches or sensors, and controlling a
• TCCR1A – Timer/Counter1 Control Register variety of lights, motors, and other
A physical outputs.
• Arduino projects can be stand-alone, or
they can be communicate with software
running on your computer (e.g. Flash,
Processing, MaxMSP.)
• The Arduino programming language is an
implementation of Wiring, a similar
Bit [7:6] – COM1A1:0 Compare Output Mode for physical computing platform, which is
Channel A based on the Processing multimedia
Bit [5:4] - COM1B1:0 Compare Output Mode for programming environment.
Channel B
Advantages
• TCCR1B – Timer/Counter1 Control Register A
• There are many other microcontrollers and
microcontroller platforms available for
physical computing. Parallax Basic Stamp,
Netmedia's BX-24, Phidgets, MIT's
Handyboard, and many others offer similar
functionality.
• Inexpensive - Arduino boards are
relatively inexpensive compared to other
Bit [0:2] – CS[10:12] Clock Select Bits microcontroller platforms.
Bit [4:3] – WGM[13:12] Waveform Generation • Cross-platform - The Arduino software
Mode
These bits are used in conjunction with TCCR1A runs on Windows, Macintosh OSX, and
Control Register bits Linux operating systems.
WGM[11:10] to set the timer/counter mode as 8- • Simple, clear programming environment -
bit Fast PWM. The Arduino programming environment is
easy-to-use for beginners, yet flexible
Arduino enough for advanced users to take
advantage of as well.
Introduction • Open source and extensible software- The
• Arduino is a tool for making computers Arduino software is published as open
that can sense and control more of the source tools, available for extension by
physical world than your desktop experienced programmers.
computer. • The language can be expanded through
• It's an open-source physical computing C++ libraries, and people wanting to
platform based on a simple microcontroller understand the technical details can make
board, and a development environment for the leap from Arduino to the AVR C
writing software for the board. programming language on which it's
based.
7. Introduction to Arduino
Duemilanove
Power
The Arduino Duemilanove can be powered via the
USB connection or with an external power supply.
The power source is selected automatically.
External (non-USB) power can come either from
an AC-to-DC adapter (wall-wart) or battery. The
adapter can be connected by plugging a 2.1mm
center-positive plug into the board's power jack.
Leads from a battery can be inserted in the Gnd
and Vin pin headers of the POWER connector.
The board can operate on an external supply of 6
to 20 volts. If supplied with less than 7V,
however, the 5V pin may supply less than five
volts and the board may be unstable. If using more
than 12V, the voltage regulator may overheat and
damage the board. The recommended range is 7 to
Overview 12 volts.
The Arduino Duemilanove ("2009") is a
microcontroller board based on the ATmega168 The power pins are as follows:
or ATmega328. It has 14 digital input/output pins (of VIN. The input voltage to the Arduino board
which 6 can be used as PWM outputs), 6 analog when it's using an external power source (as
inputs, a 16 MHz crystal oscillator, a USB connection, opposed to 5 volts from the USB connection or
a power jack, an ICSP header, and a reset button. It other regulated power source). You can supply
contains everything needed to support the voltage through this pin, or, if supplying voltage
microcontroller; simply connect it to a computer with a via the power jack, access it through this pin.
USB cable or power it with a AC-to-DC adapter or
5V. The regulated power supply used to power the
battery to get started.
microcontroller and other components on the
board. This can come either from VIN via an on-
Summary board regulator, or be supplied by USB or another
Microcontroller ATmega168 regulated 5V supply.
Operating Voltage 5V 3V3. A 3.3 volt supply generated by the on-board
Input Voltage FTDI chip. Maximum current draw is 50 mA.
7-12V GND. Ground pins.
(recommended)
Input Voltage (limits) 6-20V
14 (of which 6 provide Memory
Digital I/O Pins
PWM output)
The ATmega168 has 16 KB of flash memory for
Analog Input Pins 6 storing code (of which 2 KB is used for the
DC Current per I/O bootloader); the ATmega328has 32 KB, (also with
40 mA
Pin 2 KB used for the bootloader).
DC Current for 3.3V The ATmega168 has 1 KB of SRAM and 512
50 mA bytes of EEPROM (which can be read and written
Pin
16 KB (ATmega168) or with the EEPROM library. the ATmega328 has 2
32 KB (ATmega328) of KB of SRAM and 1 KB of EEPROM.
Flash Memory
which 2 KB used by
bootloader
1 KB (ATmega168) or 2
SRAM
KB (ATmega328)
512 bytes (ATmega168)
EEPROM
or 1 KB (ATmega328)
Clock Speed 16 MHz
8. Input and Output
Each of the 14 digital pins on the Duemilanove can be The mapping between Arduino pins and
used as an input or output, ATmega168 ports
using pinMode(), digitalWrite(),
anddigitalRead() functions. They operate at 5
volts. Each pin can provide or receive a maximum
of 40 mA and has an internal pull-up resistor
(disconnected by default) of 20-50 kOhms. In
addition, some pins have specialized functions:
Serial: 0 (RX) and 1 (TX). Used to receive (RX)
and transmit (TX) TTL serial data. These pins are
connected to the corresponding pins of the FTDI
USB-to-TTL Serial chip.
External Interrupts: 2 and 3. These pins can be
configured to trigger an interrupt on a low value, a
rising or falling edge, or a change in value. See
the attachInterrupt() function for details.
PWM: 3, 5, 6, 9, 10, and 11. Provide 8-bit PWM
output with the analogWrite() function.
SPI: 10 (SS), 11 (MOSI), 12 (MISO), 13
(SCK). These pins support SPI communication
using the SPI library. Communication
LED: 13. There is a built-in LED connected to
digital pin 13. When the pin is HIGH value, the The Arduino Duemilanove has a number of
LED is on, when the pin is LOW, it's off. facilities for communicating with a computer,
The Duemilanove has 6 analog inputs, each of another Arduino, or other microcontrollers.
which provide 10 bits of resolution (i.e. 1024 The ATmega168 and ATmega328 provide UART
different values). By default they measure from TTL (5V) serial communication, which is
ground to 5 volts, though is it possible to change available on digital pins 0 (RX) and 1 (TX). An
the upper end of their range using the AREF pin FTDI FT232RL on the board channels this serial
and the analogReference() function. communication over USB and the FTDI
Additionally, some pins have specialized drivers (included with Windows version of the
functionality: Arduino software) provide a virtual com port to
I2C: analog input pins A4 (SDA) and A5 software on the computer.
(SCL). Support I2C (TWI) communication using The Arduino software includes a serial monitor
the Wire library. which allows simple textual data to be sent to and
from the Arduino board. The RX and
There are a couple of other pins on the board: TX LEDs on the board will flash when data is
being transmitted via the FTDI chip and USB
AREF. Reference voltage for the analog inputs. connection to the computer (but not for serial
communication on pins 0 and 1).A SoftwareSerial
Reset. Bring this line LOW to reset the library allows for serial communication on any of
microcontroller. Typically used to add a reset the Duemilanove's digital pins.
button to shields which block the one on the The ATmega168 and ATmega328 also
board. support I2C (TWI) and SPI communication. The
Arduino software includes a Wire library to
simplify use of the I2C bus.
9. Programming USB Overcurrent Protection
The Arduino Duemilanove can be programmed The Arduino Duemilanove has a resettable
with the Arduino software. polyfuse that protects your computer's USB ports
The ATmega168 or ATmega328 on the Arduino from shorts and overcurrent. Although most
Duemilanove comes preburned with computers provide their own internal protection,
a bootloader that allows you to upload new code the fuse provides an extra layer of protection. If
to it without the use of an external hardware more than 500 mA is applied to the USB port, the
programmer. It communicates using the fuse will automatically break the connection until
original STK500protocol (reference, C header the short or overload is removed.
files).You can also bypass the bootloader and
program the microcontroller through the ICSP (In- Physical Characteristics
Circuit Serial Programming) header.
The maximum length and width of the
Automatic (Software) Reset Duemilanove PCB are 2.7 and 2.1 inches
respectively, with the USB connector and power
Rather then requiring a physical press of the reset jack extending beyond the former dimension.
button before an upload, the Arduino Three screw holes allow the board to be attached
Duemilanove is designed in a way that allows it to to a surface or case. Note that the distance
be reset by software running on a connected between digital pins 7 and 8 is 160 mil (0.16"),
computer. One of the hardware flow control lines not an even multiple of the 100 mil spacing of the
(DTR) of the FT232RL is connected to the reset other pins.
line of the ATmega168 or ATmega328 via a 100
nanofarad capacitor. When this line is asserted
(taken low), the reset line drops long enough to
reset the chip. The Arduino software uses this
capability to allow you to upload code by simply
pressing the upload button in the Arduino
environment. This means that the bootloader can
have a shorter timeout, as the lowering of DTR
can be well-coordinated with the start of the
upload. This setup has other implications. When
the Duemilanove is connected to either a
computer running Mac OS X or Linux, it resets
each time a connection is made to it from software
(via USB). For the following half-second or so,
the bootloader is running on the Duemilanove.
While it is programmed to ignore malformed data
(i.e. anything besides an upload of new code), it
will intercept the first few bytes of data sent to the
board after a connection is opened. If a sketch
running on the board receives one-time
configuration or other data when it first starts,
make sure that the software with which it
communicates waits a second after opening the
connection and before sending this data.
The Duemilanove contains a trace that can be cut
to disable the auto-reset. The pads on either side
of the trace can be soldered together to re-enable
it. It's labeled "RESET-EN". You may also be
able to disable the auto-reset by connecting a 110
ohm resistor from 5V to the reset line; see this
forum thread for details.
11. Arduino Varieties:
Applications
Arduino shields:
Add-on module to extend arduino’s capabilities.
Also called Daughterboard or Cape
Communication Shields
Sensors
12. Design and Development of
Magnetic Door Lock
The main aim of the work undertaken in this paper
is to sense the correctness of a secret code using COMPONENTS AND EQUIPMENT
the Arduino technology. When the correct code is
entered through keypad, it lights a green LED in Arduino Diecimila or Duemilanove board or clone
addition to operating a small solenoid which D1 Red 5-mm LED
when powered, will strongly attract the metal slug D2 Green 5-mm LED
in its center, pulling it into place, when the power R1-3 270 _ 0.5W metal film resistor
is removed, it is free to move. The secret code is K1 4 x 3 keypad
stored in EEPROM, so if the power is 0.1-inch header strip
disconnected, the code will not be lost. When T1 BC548
powered, the solenoid will strongly attract the 5V solenoid (< 100 mA)
metal slug in its center, pulling it into place. When D3 1N4004
the power is removed, it is free to move.
Keypads are normally arranged in a grid so that
when one of the keys is pressed, it connects a row
to a column. Figure beside shows a typical
arrangement for a 12-key keyboard with numbers
from 0 to 9 and * and # keys.
The key switches are arranged at the intersection
of row-and-column wires. When a key is pressed,
it connects a particular row to a particular column.
By arranging the keys in a grid like this, it
means that we only need to use 7 (4 rows +
3columns) of our digital pins rather than 12 (one
for each key).
13. Figure beside shows how you can solder seven
pins from a pin header strip onto the keypad so
that you can then connect it to the breadboard. Pin
headers are bought in strips and can be easily
snapped to provide the number of pins required.
The solenoid is an inductive load and therefore
liable to generate a back EMF, which diode D3
protects against. The solenoid is controlled by T1,
so be careful to select a solenoid that will not
draw more than 100 mA, which is the maximum
collector current of the transistor. We are using a
very low power solenoid, and this would not keep
intruders out. If you are using a more substantial
solenoid, a BD139 transistor would be better. If
the solenoid can be mounted on the breadboard,
this is all well and good. If not, you will need to
attach leads to it that connect it to the breadboard.
Hardware
The schematic diagram
15. void saveCode() EEPROM.write(3, secretCode[2]);
{ EEPROM.write(4, secretCode[3]);
EEPROM.write(1, secretCode[0]); EEPROM.write(0, 1);
EEPROM.write(2, secretCode[1]); }
void flash() delay(500);
{ digitalWrite(redPin, LOW);
digitalWrite(redPin, HIGH);
digitalWrite(greenPin, HIGH);
digitalWrite(greenPin, LOW);
}
Since each character is exactly one byte in length, and off will not reset it to 1234. Instead, you will
the code can be stored directly in the EEPROM have to comment out the line:
memory. We use the first byte of EEPROM to loadCode(); in the setup function, so that it
indicate if the code has been set. If it has not been appears as shown here:
set, the code will default to 1234. Once the code // loadCode();
has been set, the first EEPROM byte will be given
a value of 1.
Conclusion and future scope:
Putting It All Together
A Magnetic Door Lock employing Arduino
Load the completed sketch and download it to the technology is presented. We have implemented a
board . We can make sure everything is working failsafe maglock, fail secure maglock also can be
by powering up our project and entering the code implemented. Instead of keypad Reader using the
1234, at which point, the green LED should light variety of sensors and shields various
and the solenoid release. We can then change the combinations of Magnetic Door Lock can be
code to something a little less guessable by produced and installed according to the
pressing the * key and then entering four digits for requirements of any Industry.
the new code. The lock will stay unlocked until
we press the # key. If you forget your secret code, References:
unfortunately, turning the power to the project on • http://arduino.cc/
• ITP Physical Computing
• http://www.ladyada.net
• http://www.sparkfun.com
• http://seeedstudio.com
• http://coopermaa2nd.blogspot.com
By,
Sravanthi Rani Sinha S
09BD1A04A0
