This document describes an embedded password-based access control system using I2C protocol. The system uses a microcontroller with external EEPROM to store passwords. A matrix keypad is used for password entry and a relay driver interfaces with relays to control access. Hardware requirements include a microcontroller, keypad, LCD, relays, and other basic electronic components. The system allows only authorized users to access restricted areas by entering the correct password stored in the microcontroller's EEPROM.

1. EMBEDDED PASSWORD BASED ACCESS
CONTROL SYSTEM USING I2C PROTOCOL
Under the Guidance of
Submitted by
Project Title

2. ABSTRACT
The microcontroller based door locker is an access control
system that allows only authorized persons to access a
restricted area.
 The system is fully controlled by the 8 bit microcontroller
which has an 2K bits of externally interfaced EEPROM
The password is stored in EEPROM can be changed at any
time.
A matrix keypad is interfaced to the microcontroller to enter
the password while a relay driver IC is used to switch on loads
through relays.

3. BLOCK DIAGRAM

4. HARDWARE REQUIREMENTS
POWER SUPPLY BLOCK
MICROCONTROLLER (AT89S52/AT89C51)
PUSHBUTTON
LCD
MATRIX KEYPAD
 RELAY
 RELAY DRIVER
 LED
 1N4007
 CAPACITORS
 RESISTORS

5. 230 V AC
50 Hz
5V
DC
12V step down
transformer
Filter(470µf)
5v RegulatorBridge rectifier

6.  It is a smaller computer
 Has on-chip RAM, ROM, I/O ports...
RAM ROM
I/O
Port
Timer
Serial
COM
Port
Microcontroller
CPU
A single chip

7. CPU
On-chip
RAM
On-chip
ROM for
program
code
4 I/O Ports
Timer 0
Serial
Port
OSC
Interrup
t
Control
External interrupts
Timer 1
Timer/Counter
Bus
Control
TxD RxDP0 P1 P2 P3
Address/Data
Counter
Inputs

8.  Compatible with MCS®-51 Products
 8K Bytes of In-System Programmable (ISP) Flash Memory
 Endurance: 10,000 Write/Erase Cycles
 4.0V to 5.5V Operating Range
 Fully Static Operation: 0 Hz to 33 MHz
 256 x 8-bit Internal RAM
 32 Programmable I/O Lines
 Three 16-bit Timer/Counters
 Eight Interrupt Sources
 Full Duplex UART Serial Channel
 Interrupt Recovery from Power-down Mode
 Watchdog Timer
 Dual Data Pointer

10. IT IS A ELECTRO MAGNETIC SWITCH
USED TO CONTROL THE ELECTRICAL DEVICES
COPPER CORE MAGNETIC FLUX PLAYS MAIN ROLE HERE

11. The relay's switch connections are usually labeled COM, NC and
NO:
COM = Common, always connect to this; it is the moving part of
the itch.
NC = Normally Closed, COM is connected to this when the relay
coil is off.
NO = Normally Open, COM is connected to this when the relay
coil is on

12.  A keypad is a set of buttons arranged in a block or
"pad" which usually bear digits, symbols and usually a
complete set of alphabetical letters. If it mostly contains
numbers then it can also be called a numeric keypad.
 In order to detect which key is pressed from the matrix,
the row lines are to be made low one by one and read
the columns. Assume that if Row1 is made low, then
read the columns.
 If any of the key in row1 is pressed then
correspondingly the column 1will give low that is if
second key is pressed in Row1, then column2 will give
low.

13. RELAY DRIVER (ULN 2003)
ULN2003 is a high voltage and high current Darlington
transistor array
It consists of seven NPN Darlington pairs that feature high-
voltage outputs with common-cathode Clamp diode for
switching inductive loads.
The ULN2003 has a 2.7kW series base resistor for each
Darlington pair for operation directly with TTL or 5V
CMOS devices.
Current, Output Max:500mA
Voltage, Input Max:5V
Voltage, Output Max:50V

14. Fig: ULN 2003

15.  EEPROM is Electrically Erasable Programmable
Read-Only Memory that can be electrically erased
and reprogrammed..
 Unlike the EPROM chip, however, an EEPROM chip
need not be taken out of the computer or
electronic device of which it is part when a new
program or data needs to be written on it.
 AT24C02 is a two wire 2Kbits serial EEPROM by
Atmel.
 The memory is organized in 256 words of single
byte each arranged in 32 pages of 8 bytes each.

16.  The addressing of memory locations requires eight bit
addresses.
 AT24C02 is two-wire serially programmable i.e., for
programming, the data and control signals are
provided serially along with clock signals from the
other wire.
 The read-write operations are accomplished by
sending a set of control signals including the address
and/or data bits.
 The control signals must be accompanied with proper
clock signals.
 The AT24C02 has hard wire addressing of 3 bit length.
 This facilitates interfacing of a maximum of eight (23
)
24C02 devices to a system thereby, incorporating a
maximum 16Kbits memory.
 Multiple 24C02 devices can be connected to a
microcontroller based system using I2C interface.

17. LIQUID CRYSTAL DISPLAY (LCD)
Most common LCDs connected to the microcontrollers are
16x2 and 20x2 displays.
This means 16 characters per line by 2 lines and 20
characters per line by 2 lines, respectively.
The standard is referred to as HD44780U, which refers to
the controller chip which receives data from an external
source (and communicates directly with the LCD.

18. LCD BACKGROUND
If an 8-bit data bus is used the LCD will require 11 data lines
(3 control lines plus the 8 lines for the data bus)
The three control lines are referred to as EN, RS, and RW
EN=Enable (used to tell the LCD that you are sending it data)
RS=Register Select (When RS is low (0), data is treated as a command)
(When RS is High(1), data being sent is text data )
R/W=Read/Write (When RW is low (0), the data written to the LCD)
(When RW is low (0), the data reading to the LCD)

19. The numbers pressed in the matrix keypad load corresponding logical
state at the input i.e., port 1.
The program is so returned that when 1111 is pressed it switches ON
load 1 & while 2222 is pressed it switches ON load 2 and so on through a
relays interfaced through relay driver IC from the MC output
Working of project

20.  Keil an ARM Company makes C compilers, macro assemblers, real-
time kernels, debuggers, simulators, integrated environments,
evaluation boards, and emulators for ARM7/ARM9/Cortex-M3,
XC16x/C16x/ST10, 251, and 8051 MCU families.
 Compilers are programs used to convert a High Level Language to
object code. Desktop compilers produce an output object code for the
underlying microprocessor, but not for other microprocessors.

21.  i.e the programs written in one of the HLL like ‘C’ will compile
the code to run on the system for a particular processor like x86
(underlying microprocessor in the computer).
 For example compilers for Dos platform is different from the
Compilers for Unix platform So if one wants to define a compiler
then compiler is a program that translates source code into object
code.

22.  “The 8051 Microcontroller and Embedded systems” by
Muhammad Ali Mazidi and Janice Gillispie Mazidi , Pearson
Education.
 ATMEL 89S52 Data Sheets.
 www.atmel.com
 www.beyondlogic.org
 www.wikipedia.org
 www.howstuffworks.com
 www.alldatasheets.com