3. INTRODUCTION
• 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 AT89C2051 which has a
2Kbytes of ROM for the program memory.
• The system has a Keypad by which the password can be entered through
it. When the entered password equals with the password stored in the
memory then the gate gets open. If we entered a wrong password then
the Alarm is switched on.
• The default password is set .There is an button which should be placed
inside the door so that the person inside can open/close the door.
5. 89C51 MICROCONTROLLER
•89C51
•The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K
•Bytes of Flash programmable and erasable read only memory (PEROM).
•The device is manufactured using Atmel’s high-density nonvolatile memory
technology and is Compatible with the industry-standard MCS-51 instruction set
and pin out.
•The on-chip Flash allows the program memory to be reprogrammed in-system or
by a conventional non-volatile memory programmer.
•By combining a versatile 8-bit CPU with Flash on a monolithic chip, the Atmel
AT89C51 is a powerful microcomputer which provides a highly-flexible and cost-
effective solution to many embedded control applications.
7. FEATURES
•The AT89C51 provides the following standard features: 4K bytes of Flash, 128 bytes of
RAM, 32 I/O lines, two 16-bit timer/counters, five vector two-level interrupt
architecture, a full duplex serial port, and on-chip oscillator and clock circuitry.
•In addition, the AT89C51 is designed with static logic for operation down to zero
frequency and supports two software selectable power saving modes.
• The Idle Mode stops the CPU while allowing the RAM, timer/counters, serial port and
interrupt system to continue functioning.
•The Power-down Mode saves the RAM contents but freezes the oscillator disabling all
other chip functions until the next hardware reset.
•The AT89C52 implements 256 bytes of on-chip RAM. The upper 128 bytes occupy a
parallel address space to the Special Function Registers.
• That means the upper 128 bytes have the same addresses as the SFR space but are
physically separate from SFR space.
•When an instruction accesses an internal location above address 7FH, the address
mode used in the instruction specifies whether the CPU accesses the upper 128 bytes of
RAM or the SFR space. Instructions that use direct addressing access SFR space. new
features.
•In that case, the reset or inactive values of the new bits will always be 0.
8. STEPPER MOTOR
•A stepper motor (or step motor) is a brushless, synchronous electric motor that can
divide a full rotation into a large number of steps.
• The motor's position can be controlled precisely without any feedback mechanism
(see Open-loop controller), as long as the motor is carefully sized to the application.
•Stepper motors are similar to switched reluctance motors (which are very large
stepping motors with a reduced pole count, and generally are closed-loop
commutated.)
11. CHARACTERISTICS OF STEPPER MOTOR
•Stepper motors are constant power devices.
•As motor speed increases, torque decreases.
•The torque curve may be extended by using current limiting drivers and increasing the
driving voltage.
•Steppers exhibit more vibration than other motor types, as the discrete step tends to snap
the rotor from one position to another.
•This vibration can become very bad at some speeds and can cause the motor to lose torque.
•The effect can be mitigated by accelerating quickly through the problem speeds range,
physically damping the system, or using a micro-stepping driver.
•Motors with a greater number of phases also exhibit smoother operation than those with
fewer phases.
12. DIODE
•A diode is a two-terminal electronic component that conducts electric current in only one
direction.
•The term usually refers to a semiconductor diode, the most common type today, which is
a crystal of semiconductor connected to two electrical terminals, a P-N junction.
13. RESISTANCE
•The electrical resistance of an object is a measure of its opposition to the passage of a
steady electric current.
• An object of uniform cross section will have a resistance proportional to its length and
inversely proportional to its cross-sectional area, and proportional to the resistivity of the
material.
14. CRYSTAL OSCILLATOR
•A crystal oscillator is an electronic circuit that uses the mechanical resonance of a vibrating
crystal of piezoelectric material to create an electrical signal with a very precise frequency.
• This frequency is commonly used to keep track of time (as in quartz wristwatches), to
provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for
radio transmitters and receivers.
• The most common type of piezoelectric resonator used is the quartz crystal, so oscillator
circuits designed around them were called "crystal oscillators".
15. VOLTAGE REGULATOR
•A voltage regulator is an electrical regulator designed to automatically maintain a
constant voltage level.
• It may use an electromechanical mechanism, or passive or active electronic components.
Depending on the design, it may be used to regulate one or more AC or DC voltages.
16. CAPACITOR
•A capacitor or condenser is a passive electronic component consisting of a pair of
conductors separated by a dielectric (insulator).
•When a potential difference (voltage) exists across the conductors, an electric field is
present in the dielectric.
•This field stores energy and produces a mechanical force between the conductors.
•The effect is greatest when there is a narrow separation between large areas of
conductor; hence capacitor conductors are often called plates
17. MOMENTARY SWITCH
•In electronics, a switch is an electrical component that can break an electrical circuit,
interrupting the current or diverting it from one conductor to another.
• The most familiar form of switch is a manually operated electromechanical device with
one or more sets of electrical contacts.
18. LCD
•The JHD 162A LCD is fully compatible with the HD44780 LCD.
•Hence, the same set of codes will work for both. It is a 16×2 LCD module i.e. it has 16
columns and 2 rows for display.
•It can operate in either 8 bit mode or 4 bit mode.
•In 8 bit mode, an 8 bit is data is sent to the LCD from the MCU whereas in 4 bit mode,
4 bits of data are sufficient to operate it.
19. •FEATURES
•Display construction………………..... 16 Characters * 2 Lines
•Display mode…………………………….. TN/STN
•Display type………………………………. Positive Transflective
•Backlight……………………………………. LED(B/5.0V)
•Viewing direction………………………. 6 o’clock
•Operating temperature……………… Indoor
•Driving voltage……………………….…. Single power
•Driving method………………………….. 1/16 duty,1/5 bias
•Type…………………………………………… COB (Chip On Board)
•Number of data line…………………… 8-bit parallel
•Connector………………………………….. Pin
