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

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. POWER SUPPLY Bridge rectifier 5v Regulator 230 V AC 50 Hz 5V DC
Filter(470µf)
12V step down
transformer

6. It is a smaller computer Has on-chip RAM, ROM, I/O ports...
MICROCONTROLLER
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. INTERNAL STRUCTURE OF A MICRO CONTROLLER-AT89S52/51
CPU
On-chip RAM
On-chip ROM for program code
4 I/O Ports
Timer 0
Serial Port
OSC
Interrupt Control
External interrupts
Timer 1
Timer/Counter
Bus Control
TxD RxD
P0 P1 P2 P3
Address/Data
Counter Inputs

8. Features of AT89S51/52 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

9. Pin Description

10. RELAY 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. Keypad
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
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. Contd..
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. If an 8-bit data bus is used the LCD will require 11 data lines
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. Working of project
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

20. Soft ware Requirements
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. BIBILOGRAPHY
“The Microcontroller and Embedded systems” by Muhammad Ali Mazidi and Janice Gillispie Mazidi , Pearson Education.
ATMEL 89S52 Data Sheets.