Digital Code Locking System

INDEX

1. ABSTRACT

2. BLOCK DIAGRAM

3. MICROCONTROLLER

3.1 A Brief History of 8051

3.2 Description of 89C52 Microcontroller

3.3 Block Diagram of Microcontroller

3.4 Pin Configurations

3.5 Timers

3.6 Interrupts

3.7 Special function registers:

3.8 Memory Organization

4. POWER SUPPLY

4.1 Description

4.2 Block Diagram

4.3 Circuit Diagram

4.4 IC Voltage Regulators

5. ULN 2003

6. STEPPER MOTOR

7. KEYPAD

8. LCD

9. KEIL SOFTWARE

9.1 Software Description

10. CIRCUIT DIAGRAM

11. WORKING PRINCIPLE

12. SOURCE CODING

13. CONCLUSION

14. FUTURE SCOPE

15. BIBLIOGRAPHY

DIGITAL CODE LOCKING SYSTEMABSTRACT

The aim of this project is to provide the security. Now a days security system

is must for every organization. Access control system is one system that is used for security

purpose in many organizations. The main aim of this project is to provide access only if the

password of particular user is matched. So, every user is given a unique password. So, that

access is denied to unauthorized persons.

This system can be used in military areas, bank security and security for important

documents.

Our system has intelligent of allowing only valid passwords. This is 89C52

microcontroller based project which is interfaced to keypad, LCD- display and Stepper motor.

We used a 4x3 matrix keypad to have an access to system. An LCD (16x2) and a stepper motor

to open or close the door. We have used KEIL for microcontroller programming. The software

prompts user to enter a password and checks its validity .If it’s valid the door is opened using

Stepper motor.

HARDWARE COMPONENTS:

1. 89C52 MICROCONTROLLER

2. ULN 2003 DRIVER IC

3. STEPPER MOTOR.

4. LCD DISPLAY.

5. KEY PAD.

SIMULATION:

TOOL: KEIL MICROVISION

PLATFORM: WINDOWS

LANGUAGE: EMBEDDED ‘C’

Block diagram

ULNDRIVER LCD

DISPLAY

4x3 MATRIX KEYPAD

AT 89C52

MICROCONTROLLER

STEPPER MOTOR

MICROCONTROLLER

3.1 A Brief History of 8051

In 1981, Intel Corporation introduced an 8 bit microcontroller called 8051. This

microcontroller had 128 bytes of RAM, 4K bytes of chip ROM, two timers, one serial

port, and four ports all on a single chip. At the time it was also referred as “A SYSTEM

ON A CHIP”

The 8051 is an 8-bit processor meaning that the CPU can work only on 8 bits data

at a time. Data larger than 8 bits has to be broken into 8 bits pieces to be processed by the

CPU. The 8051 has a total of four I\O ports each 8 bit wide.

There are many versions of 8051 with different speeds and amount of on-chip

ROM and they are all compatible with the original 8051. This means that if you write a

program for one it will run on any of them.

The 8052 is an original member of the 8051 family. There are two other members

in the 8051 family of microcontrollers. They are 8052 and 8031. All the three

microcontrollers will have the same internal architecture, but they differ in the following

aspects.

8031 has 128 bytes of RAM, two timers and 6 interrupts.

89S51 has 4KB ROM, 128 bytes of RAM, two timers and 6

interrupts.

89S52 has 8KB ROM, 128 bytes of RAM, three timers and 8

interrupts.

Of the three microcontrollers, 89S51 is the most preferable. Microcontroller

supports both serial and parallel communication.

In the concerned project 89S52 microcontroller is used. Here microcontroller used

is AT89S52, which is manufactured by ATMEL laboratories.

3.2 Description of 89C52 Microcontroller

The AT89S52 provides the following standard features: 8Kbytes of Flash, 256

bytes of RAM, 32 I/O lines, three 16-bit timer/counters, six-vector two-level interrupt

architecture, a full duplex serial port, on-chip oscillator, and clock circuitry. In addition,

the AT89S52 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.

By combining a versatile 8-bit CPU with Flash on a monolithic chip, the

AT89S52 is a powerful microcomputer which provides a highly flexible and cost

effective solution to many embedded control applications.

Features of Microcontroller (89S52)

Compatible with MCS-51 Products

8 Kbytes of In-System Reprogrammable Flash Memory

Endurance: 1,000 Write/Erase Cycles

Fully Static Operation: 0 Hz to 24 MHz

Three-Level Program Memory Lock

256 x 8-Bit Internal RAM

32 Programmable I/O Lines

Three 16-Bit Timer/Counters

Eight vector two level Interrupt Sources

Programmable Serial Channel

Low Power Idle and Power Down Modes

In addition, the AT89S52 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.

3.3 Block Diagram of Microcontroller

Figure 3.1 Block Diagram Of 89S52

3.4 Pin Configurations

Figure 3.2 Pin Diagram of 89S52

Pin Description

VCC

Pin 40 provides Supply voltage to the chip. The voltage source is +5v

GND.

Pin 20 is the grounded

Port 0

Port 0 is an 8-bit open drain bidirectional I/O port from pin 32 to 39. As an output

port each pin can sink eight TTL inputs. When 1s are written to port 0 pins, the pins can

be used as high-impedance inputs. Port 0 may also be configured to be the multiplexed

low-order address/data bus during accesses to external program and data memory. In this

mode P0 has internal pull-ups.

Port 0 also receives the code bytes during Flash programming, and outputs the

code bytes during program verification. External pull-ups are required during program

verification.

Port 1

Port 1 is an 8-bit bidirectional I/O port with internal pull-ups from pin 1 to 8. The

Port 1 output buffers can sink/source four TTL inputs. When 1s are written to Port 1 pins

they are pulled high by the internal pull-ups and can be used as inputs. As inputs, Port 1

pins that are externally being pulled low will source current (IIL) because of the internal

pull-ups.

In addition, P1.0 and P1.1 can be configured to be the timer/counter 2 external

count input (P1.0/T2) and the timer/counter 2 trigger input (P1.1/T2EX), respectively, as

shown in following table.

Port 1 also receives the low-order address bytes during Flash programming and

program verification.

Port 2

Port 2 is an 8-bit bidirectional I/O port with internal pull-ups from pin 21 to 28.

The Port 2 output buffers can sink / source four TTL inputs. When 1s are written to Port

2 pins they are pulled high by the internal pull-ups and can be used as inputs. As inputs,

Port 2 pins that are externally being pulled low will source current (IIL) because of the

internal pull-ups.

Port 2 emits the high-order address byte during fetches from external program

memory and during accesses to external data memory that uses 16-bit addresses (MOVX

@ DPTR). In this application it uses strong internal pull-ups when emitting 1s. During

accesses to external data memory that uses 8-bit addresses (MOVX @ RI), Port 2 emits

the contents of the P2 Special Function Register. Port 2 also receives the high-order

address bits and some control signals during Flash programming and verification.

Port 3

Port 3 is an 8-bit bidirectional I/O port with internal pull-ups from pin 10 to 17.

The Port 3 output buffers can sink / source four TTL inputs. When 1s are written to

Port 3 pins they are pulled high by the internal pull-ups and can be used as inputs. As

inputs, Port 3 pins that are externally being pulled low will source current (IIL)

because of the pull-ups.

Port 3 also serves the functions of various special features of the AT89C52 as

listed below:

Table 3.1 Special Features of port3

Port 3 also receives some control signals for Flash programming and

programming verification.

RST

Pin 9 is the Reset input. It is active high. Upon applying a high pulse to this pin,

the microcontroller will reset and terminate all activities. A high on this pin for two

machine cycles while the oscillator is running resets the device.

ALE/PROG

Address Latch is an output pin and is active high. Address Latch Enable output

pulse for latching the low byte of the address during accesses to external memory.

This pin is also the program pulse input (PROG) during Flash programming. In

normal operation ALE is emitted at a constant rate of 1/6 the oscillator frequency, and

may be used for external timing or clocking purposes.

Note, however, that one ALE pulse is skipped during each access to external Data

Memory. If desired, ALE operation can be disabled by setting bit 0 of SFR location

8EH. With the bit set, ALE is active only during a MOVX or MOVC instruction.

Otherwise, the pin is weakly pulled high. Setting the ALE-disable bit has no effect if

the microcontroller is in external execution mode.

PSEN

Program Store Enable is the read strobe to external program memory. When the

AT89S52 is executing code from external program memory, PSEN is activated twice

each machine cycle, except that two PSEN activations are skipped during each access to

external data memory.

EA/VPP

External Access Enable EA must be strapped to GND in order to enable the

device to fetch code from external program memory locations starting at 0000H up to

FFFFH. Note, however, that if lock bit 1 is programmed, EA will be internally latched on

reset. EA should be strapped to VCC for internal program executions. This pin also

receives the 12-volt programming enable voltage (VPP) during Flash programming when

12-volt programming is selected.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating

circuit.

XTAL2

Output from the inverting oscillator amplifier.

Oscillator Characteristics

XTAL1 and XTAL2 are the input and output, respectively, of an inverting

amplifier which can be configured for use as an on chip oscillator, as shown in Figure

5.3. Either a quartz crystal or ceramic resonator may be used. To drive the device from an

external clock source, XTAL2 should be left unconnected while XTAL1 is driven as

shown in Figure 5.4.

Figure 3.3 crystal connections

Figure 3.4 External Clock Drive Configuration

There are no requirements on the duty cycle of the external clock signal, since the

input to the internal clocking circuitry is through a divide-by two flip-flop, but minimum

and maximum voltage high and low time specifications must be observed.

Idle Mode

In idle mode, the CPU puts itself to sleep while all the on-chip peripherals remain

active. The mode is invoked by software. The content of the on-chip RAM and all the

special functions registers remain unchanged during this mode. The idle mode can be

terminated by any enabled interrupt or by a hardware reset. It should be noted that when

idle is terminated by a hardware reset, the device normally resumes program execution,

from where it left off, up to two machine cycles before the internal reset algorithm takes

control.

On-chip hardware inhibits access to internal RAM in this event, but access to the

port pins is not inhibited. To eliminate the possibility of an unexpected write to a port pin

when Idle is terminated by reset, the instruction following the one that invokes Idle

should not be one that writes to a port pin or to external memory.

Power down Mode

In the power down mode the oscillator is stopped, and the instruction that invokes

power down is the last instruction executed. The on-chip RAM and Special Function

Registers retain their values until the power down mode is terminated. The only exit from

power down is a hardware reset. Reset redefines the SFRs but does not change the on-

chip RAM. The reset should not be activated before VCC is restored to its normal

operating level and must be held active long enough to allow the oscillator to restart and

stabilize.

Table 3.2 Status Of External Pins During Idle and Power Down Mode

Program Memory Lock Bits

On the chip are three lock bits which can be left unprogrammed (U) or can be

programmed (P) to obtain the additional features listed in the table 5.4. When lock bit 1 is

programmed, the logic level at the EA pin is sampled and latched during reset. If the

device is powered up without a reset, the latch initializes to a random value, and holds

that value until reset is activated. It is necessary that the latched value of EA be in

agreement with the current logic level at that pin in order for the device to function

properly.

Table 3.3 Lock Bit Protection Modes

TIMERS

Timer 0 and 1

Timer 0 and Timer 1 in the AT89S52 operate the same way as Timer 0 and Timer

1 in the AT89S52.

Register pairs (TH0, TL1), (TH1, TL1) are the 16-bit counter registers for timer/c;

ounters 0 and 1.

Timer 2

Timer 2 is a 16-bit Timer/Counter that can operate as either a timer or an event

counter. The type of operation is selected by bit C/T2 in the SFR T2CON. Timer 2 has

three operating modes: capture, auto-reload (up or down counting), and baud rate

generator. The modes are selected by bits in T2CON, as shown in Table 5.2. Timer 2

consists of two 8-bit registers, TH2 and TL2. In the Timer function, the TL2 register is

incremented every machine cycle. Since a machine cycle consists of 12 oscillator periods,

the count rate is 1/12 of the oscillator frequency.

Table 3.4 Timer 2 Operating Modes

In the Counter function, the register is incremented in response to a 1-to-0

transition at its corresponding external input pin, T2. In this function, the external input is

sampled during S5P2 of every machine cycle. When the samples show a high in one

cycle and a low in the next cycle, the count is incremented. The new count value appears

in the register during S3P1 of the cycle following the one in which the transition was

detected. Since two machine cycles (24 oscillator periods) are required to recognize a 1-

to-0 transition, the maximum count rate is 1/24 of the oscillator frequency. To ensure that

a given level is sampled at least once before it changes, the level should be held for at

least one full machine cycle.

There are no restrictions on the duty cycle of external input signal, but it should

for at least one full machine to ensure that a given level is sampled at least once before it

changes.

Capture Mode

In the capture mode, two options are selected by bit EXEN2 in T2CON. If

EXEN2 = 0, Timer 2 is a 16-bit timer or counter which upon overflow sets bit TF2 in

T2CON.This bit can then be used to generate an interrupt. IfEXEN2 = 1, Timer 2

performs the same operation, but a 1-to-0 transition at external input T2EX also causes

the current value in TH2 and TL2 to be captured into RCAP2H andRCAP2L,

respectively. In addition, the transition at T2EXcauses bit EXF2 in T2CON to be set. The

EXF2 bit, likeTF2, can generate an interrupt.

Auto-reload (Up or Down Counter)

Timer 2 can be programmed to count up or down when configured in its 16-bit

auto-reload mode. This feature is invoked by the DCEN (Down Counter Enable) bit

located in the SFR T2MOD (see Table 4). Upon reset, the DCEN bit is set to 0 so that

timer 2 will default to count up. When DCEN is set, Timer 2 can count up or down,

depending on the value of the T2EX pin.

Table3.5: T2MOD-Timer 2 Mode Control Register

Table3.6: T2CON-Timer/Counter2 Control Register

3.5 Interrupts

The AT89C52 has a total of six interrupt vectors: two external interrupts (INT0

and INT1), three timer interrupts (Timers 0, 1, and 2), and the serial port interrupt. These

interrupts are all shown in Figure 2.5

Figure 3.5 Interrupts source

Each of these interrupt sources can be individually enabled or disabled by setting

or clearing a bit in Special Function Register IE. IE also contains a global disable bit, EA,

which disables all interrupts at once.

Note that Table 5.3 shows that bit position IE.6 is unimplemented. In the

AT89C51, bit position IE.5 is also unimplemented. User software should not write 1s to

these bit positions, since they may be used in future AT89 products.

Table 3.7 Interrupts Enable Register

Timer 2 interrupt is generated by the logical OR of bits TF2 and EXF2 in register

T2CON. Neither of these flags is cleared by hardware when the service routine is

vectored to. In fact, the service routine may have to determine whether it was TF2 or

EXF2 that generated the interrupt, and that bit will have to be cleared in software.

The Timer 0 and Timer 1 flags, TF0 and TF1, are set at S5P2 of the cycle in

which the timers overflow. The values are then polled by the circuitry in the next cycle.

However, the Timer 2 flag, TF2, is set at S2P2 and is polled in the same cycle in which

the timer overflows.

3.6 Special function registers:

Special function registers are the areas of memory that control specific

functionality of the 89c52 microcontroller.

a) Accumulator (0E0h)

As its name suggests, it is used to accumulate the results of large no. of

instructions. It can hold 8 bit values.

b) B register (oFoh)

The B register is very similar to accumulator. It may hold 8-bit value. The B

register is only used by MUL AB and DIV AB instructions. In MUL AB the higher byte

of the products gets stored in B register. In DIV AB the quotient gets stored in B with the

remainder in A.

c) Stack pointer (081h)

The stack pointer holds 8-bit value. This is used to indicate where the next value

to be removed from the stack should be taken from. When a value is to be pushed on to

the stack, the 8052 first store the value of SP and then store the value at the resulting

memory location. When a value is to be popped from the stack, the 8052 returns the value

from the memory location indicated by SP and then decrements the value of SP.

d) Data pointer (Data pointer low/high, address 82/83h)

The SFRs DPL and DPH work together to represent a 16-bit value called the data

pointer. The data pointer is used in operations regarding external RAM and some

instructions code memory. It is a 16-bit SFR and also an addressable SFR.

e) Program counter

The program counter is a 16 bit register, which contains the 2 byte address, which

tells the next instruction to execute to be found in memory. When the 8052 is initialized

PC starts at 0000h and is incremented each time an instruction is executes. It is not

addressable SFR.

f) PCON (power control, 87h)

The power control SFR is used to control the 8052’s power control modes.

Certain operation modes of the 8052 allow the 8052 to go into a type of “sleep mode”

which consumes low power.

g)TCON(Timer control, 88h)

The timer mode control SFR is used to configure and modify the way in which

the 8052’s two timers operate. This SFR controls whether each of the two timers is

running or stopped and contains a flag to indicate that each timer has overflowed.

Additionally, some non-timer related bits are located in TCON SER. These bits are used

to configure the way in which the external interrupt flags are activated, which are set

when an external interrupt occur.

h)TMOD(Timer Mode,89h)

SMOD ---- --- ---- GF1 GF0 PD IDL

TF1 TR1 TF0 TR0 IE1 IT1 IE0 IT0

The timer mode SFR is used to configure the mode of operation of each of the

two timers. Using this SR your program may configure each timer to be a 16-bit timer, or

13 bit timer, 8-bit auto reload timer, or two separate timers. Additionally you may

configure the timers to only count when an external pin is activated or to count “events”

that are indicated on an external pin.

TIMER1 TIMER0

i) T0 (Timer 0 low/ high, address 8A/ 8C h)

These two SFRs together represent timer 0. Their exact behavior depends on how

the timer is configured in the TMOD SFR; however, these timers always count up. What

is configurable is how and when they increment value.

j) T1 (Timer 1 low/ high, address 8B/ 8D h)

These two SFRs together represent timer 1. Their exact behavior depends on how

the timer is configured in the TMOD SFR; however, these timers always count up. What

is configurable is how and when they increment in value.

k) P0 (Port 0, address 80h, bit addressable)

This is port 0 latch. Each bit of this SFR corresponds to one of the pins on a micro

controller. Any data to be outputted to port 0 is first written on P0 register. For e.g., bit 0

of port 0 is pin P0.0, bit 7 is pin P0.7. Writing a value of 1 to a bit of this SFR will send a

high level on the corresponding I/O pin whereas a value of 0 will bring it to low level.

Gate

C/ T M1 M0 Gate

C/ T M1 M0

l) P1(Port 1, address 90h, bit addressable)





m) P2 (Port 2, address 0A0h, bit addressable)





n) P3 (Port 3, address 0B0h, bit addressable)





o) IE (Interrupt Enable, 0A8h)

The interrupt enable SFR is used to enable and disable specific interrupts. The

low 7 bits of the SFR are used to enable/disable the specific interrupts, where the MSB

bit is used to enable or disable all the interrupts. Thus, if the high bit of IE 0 all interrupts

are disabled regardless of whether an individual interrupt is enabled by setting a lower

bit.

EA

_ _ _

ET2 ES ET1 EX1 ET0 EX0

p) IP (Interrupt Priority, 0B8h)

The interrupt priority SFR is used to specify the relative priority of each interrupt.

On 8052, an interrupt may be either low or high priority. An interrupt may interrupt

interrupts. For e.g., if we configure all interrupts as low priority other than serial

interrupt. The serial interrupt always interrupts the system; even if another interrupt is

currently executing no other interrupt will be able to interrupt the serial interrupt routine

since the serial interrupt routine has the highest priority.

_ _ _ _ _ _

PT2 PS PT1 PX1 PT0 PX0

q)PSW (Program Status Word, 0D0h)

The Program Status Word is used to store a number of important bits that are set

and cleared by 8052 instructions. The PSW SFR contains the carry flag, the auxiliary

carry flag, the parity flag and the overflow flag. Additionally, it also contains the register

bank select flags, which are used to select, which of the “R” register banks currently in

use.

r) SBUF (Serial Buffer, 99h)

CY AC F0 RS1 RS0 OV - - - - P

SBUF is used to hold data in serial communication. It is physically two registers.

One is writing only and is used to hold data to be transmitted out of 8052 via TXD. The

other is read only and holds received data from external sources via RXD. Both mutually

exclusive registers use address 99h.

3.7 Memory Organization

The total memory of 89C52 system is logically divided in Program memory and

Data memory. Program memory stores the programs to be executed, while data memory

stores the data like intermediate results, variables and constants required for the execution

of the program. Program memory is invariably implemented using EPROM, because it

stores only program code which is to be executed and thus it need not be written into.

However, the data memory may be read from or written to and thus it is implemented

using RAM.

Further, the program memory and data memory both may be categorized as on-

chip (internal) and external memory, depending upon whether the memory physically

exists on the chip or it is externally interfaced. The 89C52 can address 8Kbytes on-chip

memory whose map starts from 0000H and ends at 1FFFH. It can address 64Kbytes of

external program memory under the control of PSEN (low) signal.

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

128bytes 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. For

example, the following direct addressing instruction accesses the SFR at location 0A0H

(which is P2).

MOV 0A0H, #data

Instructions that use indirect addressing access the upper128 bytes of RAM. For

example, the following indirect addressing instruction, where R0 contains 0A0H,

accesses the data byte at address 0A0H, rather than P2 (whose address is 0A0H)

.MOV @R0, #data

Note that stack operations are examples of indirect addressing, so the upper 128 bytes of

data RAM are available as stack space.

4. REGULATED POWER SUPPLY

4.1 Description:

A variable regulated power supply, also called a variable bench power

supply, is one where you can continuously adjust the output voltage to your requirements.

Varying the output of the power supply is the recommended way to test a project after

having double checked parts placement against circuit drawings and the parts placement

guide. This type of regulation is ideal for having a simple variable bench power supply.

Actually this is quite important because one of the first projects a hobbyist should

undertake is the construction of a variable regulated power supply. While a dedicated

supply is quite handy e.g. 5V or 12V, it's much handier to have a variable supply on

hand, especially for testing. Most digital logic circuits and processors need a 5 volt power

supply. To use these parts we need to build a regulated 5 volt source. Usually you start

with an unregulated power supply ranging from 9 volts to 24 volts DC (A 12 volt power

supply is included with the Beginner Kit and the Microcontroller Beginner Kit.). To

make a 5 volt power supply, we use a LM7805 voltage regulator IC .

http://www.iguanalabs.com/mbkit.htm

http://www.iguanalabs.com/1stled.htm

The LM7805 is simple to use. You simply connect the positive lead of your

unregulated DC power supply (anything from 9VDC to 24VDC) to the Input pin, connect

the negative lead to the Common pin and then when you turn on the power, you get a 5

volt supply from the Output pin.

Circuit Features:

Brief description of operation: Gives out well regulated +5V output, output

current capability of 100 mA

Circuit protection: Built-in overheating protection shuts down output when

regulator IC gets too hot

Circuit complexity: Very simple and easy to build

Circuit performance: Very stable +5V output voltage, reliable operation

Availability of components: Easy to get, uses only very common basic

components

Design testing: Based on datasheet example circuit, I have used this circuit

successfully as part of many electronics projects

Applications: Part of electronics devices, small laboratory power supply

Power supply voltage: Unregulated DC 8-18V power supply

Power supply current: Needed output current + 5 mA

Component costs: Few dollars for the electronics components + the input

transformer cost

4.2 Block Diagram:

3.3 Circuit Diagram:

Basic Power Supply Circuit:

Above is the circuit of a basic unregulated dc power supply. A bridge rectifier

D1 to D4 rectifies the ac from the transformer secondary, which may also be a block

rectifier such as WO4 or even four individual diodes such as 1N4004 types. (See later re

rectifier ratings).

The principal advantage of a bridge rectifier is you do not need a centre tap on the

secondary of the transformer. A further but significant advantage is that the ripple

frequency at the output is twice the line frequency (i.e. 50 Hz or 60 Hz) and makes

filtering somewhat easier.

As a design example consider we wanted a small unregulated bench supply for

our projects. Here we will go for a voltage of about 12 - 13V at a maximum output

current (IL) of 500ma (0.5A). Maximum ripple will be 2.5% and load regulation is 5%.

Now the RMS secondary voltage (primary is whatever is consistent with your

area) for our power transformer T1 must be our desired output Vo PLUS the voltage

drops across D2 and D4 (2 * 0.7V) divided by 1.414.

This means that Vsec = [13V + 1.4V] / 1.414 which equals about 10.2V. Depending on

the VA rating of your transformer, the secondary voltage will vary considerably in

accordance with the applied load. The secondary voltage on a transformer advertised as

say 20VA will be much greater if the secondary is only lightly loaded.

If we accept the 2.5% ripple as adequate for our purposes then at 13V this

becomes 13 * 0.025 = 0.325 Vrms. The peak to peak value is 2.828 times this value. Vrip

= 0.325V X 2.828 = 0.92 V and this value is required to calculate the value of C1. Also

required for this calculation is the time interval for charging pulses. If you are on a 60Hz

system it it 1/ (2 * 60) = 0.008333 which is 8.33 milliseconds. For a 50Hz system it is

0.01 sec or 10 milliseconds.

Remember the tolerance of the type of capacitor used here is very loose. The

important thing to be aware of is the voltage rating should be at least 13V X 1.414 or

18.33. Here you would use at least the standard 25V or higher (absolutely not 16V).With

our rectifier diodes or bridge they should have a PIV rating of 2.828 times the Vsec or at

least 29V. Don't search for this rating because it doesn't exist. Use the next highest

standard or even higher. The current rating should be at least twice the load current

maximum i.e. 2 X 0.5A or 1A. A good type to use would be 1N4004, 1N4006 or 1N4008

types.

These are rated 1 Amp at 400PIV, 600PIV and 1000PIV respectively. Always be

on the lookout for the higher voltage ones when they are on special.

4.4 IC Voltage Regulators:

Voltage regulators comprise a class of widely used ICs. Regulator IC units

contain the circuitry for reference source, comparator amplifier, control device, and

overload protection all in a single IC. Although the internal construction of the IC is

somewhat different from that described for discrete voltage regulator circuits, the external

operation is much the same. IC units provide regulation of either a fixed positive voltage,

a fixed negative voltage, or an adjustably set voltage.

A power supply can be built using a transformer connected to the ac supply line to

step the ac voltage to desired amplitude, then rectifying that ac voltage, filtering with a

capacitor and RC filter, if desired, and finally regulating the dc voltage using an IC

regulator. The regulators can be selected for operation with load currents from hundreds

of mill amperes to tens of amperes, corresponding to power ratings from mill watts to

tens of watts.

Three-Terminal Voltage Regulators:

Fixed Positive Voltage Regulators:

Vin

Vout

C1 C2

IN OUT78XX

GND

Fig shows the basic connection of a three-terminal voltage regulator IC to a load.

The fixed voltage regulator has an unregulated dc input voltage, Vi, applied to one input

terminal, a regulated output dc voltage, Vo, from a second terminal, with the third

terminal connected to ground. While the input voltage may vary over some permissible

voltage range, and the output load may vary over some acceptable range, the output

voltage remains constant within specified voltage variation limits. A table of positive

voltage regulated ICs is provided in table. For a selected regulator, IC device

specifications list a voltage range over which the input voltage can vary to maintain a

regulated output voltage over a range of load current. The specifications also list the

amount of output voltage change resulting from a change in load current (load regulation)

or in input voltage (line regulation).

TABLE: Positive Voltage Regulators in 7800 series

IC No. Output voltage(v) Maximum input voltage(v)

7805

7806

7808

7810

7812

7815

7818

7824

+5

+6

+8

+10

+12

+15

+18

+24

35V

40V

ULN2003

5.ULN DRIVER

ULN is mainly suited for interfacing between low-level circuits and

multiple peripheral power loads,. The series ULN20XX high voltage, high current

Darlington arrays feature continuous load current ratings. The driving circuitry in- turn

decodes the coding and conveys the necessary data to the stepper motor, this module aids

in the movement of the arm through steppers.

The driver makes use of the ULN2003 driver IC, which contains an array of 7

power Darlington arrays, each capable of driving 500mA of current. At an approximate

duty cycle, depending on ambient temperature and number of drivers turned on,

simultaneously typical power loads totaling over 230w can be controlled.

The main features of ULN2003 are as follows:

Seven Darlington per package

Output current 500ma per driver (600ma peak)

Output voltage 50v

Integrated suppression diodes for inductive loads

Outputs can be paralleled for high current TTL/CMOS/DTL compatible inputs

Inputs pinned opposite outputs to simplify layout.

Transient protected outputs

Dual In-Line plastic package or small-Outline IC package.

Relay Driver ULN 2803:

The ULN2803A is a high-voltage, high-current Darlington transistor

array. The device consists of eight npn Darlington pairs that feature high-voltage

outputs with common-cathode clamp diodes for switching inductive loads. The

collector-current rating of each Darlington pair is 500 mA. The Darlington pairs

may be connected in parallel for higher current capability.

Features:

500-mA Rated Collector Current (Single Output)

High-Voltage Outputs . . . 50 V

Output Clamp Diodes

Inputs Compatible With Various Types of Logic

Relay Driver Applications

Compatible with ULN2800A Series

IC Description:

Figure Pin Diagram

Figure Logic Diagram

Figure 2 Schematic Diagram

Applications:

The applications include relay drivers, hammer drivers, lamp drivers,

display drivers (LED and gas discharge), line drivers, and logic buffers. The

ULN2803A has a 2.7-kΩ series base resistor for each Darlington pair for

operation directly with TTL or 5-V CMOS devices

6. Stepper motor

Description:

A stepper motor is an electromechanical device which converts electrical

pulses into discrete mechanical movements. The stepper motor is used for position

control in applications like disk drives and robotics.

The name stepper is used because this motor rotates through a fixed angular step in

response to each input curent pulse received by it’s controller. In recent years, there has

been wide-spread demand of stepping motors because of th eexplosive growth of

computer industry. Their popularity is due to th efact that they can be controlled directly

by computers, microprocessors and programmable controllers. Stepper motors are

ideally suited for situations where precise positon and precise speed control are required

without the use of closed-loop feedback. When a definite number of pulses are supplied ,

th eshaft turns through a definite known angle. This fact mekes th emotor well suited for

open-loop position control because no feedback need be taken from the output shaft.

Every stepper motor has a permanent magnet rotor also kown as shaft surrounded by a

stator poles. The most common stepper motor s have four stator windings that are paired

with a center-tapped. This type of stepper motor is commonly referred to as a four-phase

stepper motor. The center tap allows a change of current direction in each of two coils

when a winding is grounded,there by resulting in a polarity change of the stator.

The shaft or spindle of a stepper motor rotates in discrete step increments when electrical

command pulses are applied to it in the proper sequence. The direction of the rotation is

determined by the stator poles.the stator poles are determined by the current sent through

the wire coils. As the pol;arity of the current is changed, the polarity is also changed

causing th reverse motion of the motor The sequence of the applied pulses is directly

related to the direction of motor shafts rotation.. The speed of the motor shafts rotation is

directly related to the frequency of the input pulses and the length of rotation is directly

related to the number of input pulses applied. While a conventional motor shaft moves

freely,stepper motor shaft moves ina fixed repeatable increment which allows one to

move it to a precise position.this repeatable fixed movement is possible as a result of

basic magnetic theory where poles of he same polarity repel and opposite poles attract.

The stepper motor converts digital signals into fixed mechanical increment of motion. It

thereby provides a natural interface with the digital computer. It is a synchronous motor

such that the rotor rotates a specific incremental number of degrees for each pulse input

given to the motor system. These motors can provide accurate positioning without the

need of position feedback sensors when compared to other motors. The position is known

simply by keeping track of the input step pulses. Usually, position information can be

obtained simply by keeping count of the pulses sent to the motor thereby eliminating the

need of expensive position sensors and feedback controls

Stepper motors are rated by the torque they produce,step angle,steps per second and the

number of teeth on rotor.

The minimum degree of rotation with which the stepper motor turns for a single pulse if

supply to one wire or a pair is called step angle. The minimum step angle is always a

function of the number of teeth on rotor .i.e.,the smaller the step angle the more teeth the

rotor possess.

Steps per complete revolution = Number of phases (coils) x

Number of teeth on rotor

http://en.wikipedia.org/wiki/Torque

Smaller the step angle ,greater the number of steps per revolution and higher the

resolution or the accuracy of positioning obtained. The step angles can be as small as

0.72˚ or as large as 90˚. The motor speed is measured in steps per second.

Steps per second = (Revolution per minute x steps per Revolution)/ 60

Stepping motors has the extraordinary ability to operate at very high speeds(upto 20,000

steps per second ) and yet to remain fully in synchronism with the command pulses, when

the pulse rate is high ,the shaft rotation seems continuous. If the stepping rate is

increased too quickly, the motor loses synchronism and stops. Stepper motors are

designed to operate for long periods with the rotor held in a fixed position and with rated

current flowing in the stator windings whereas for most of the other motors, this results in

collapse of back emf and a very high current which can lead to a quick burn out.

A stepper motor is a special kind of motor that moves in individual steps which are

usually .9 degrees each. Each step is controlled by energizing coils inside the motor

causing the shaft to move to the next position. Turning these coils on and off in sequence

will cause the motor to rotate forward or reverse. The time delay between each step

determines the motor's speed. Steppers can be moved to any desired position reliably

by sending them the proper number of step pulses.

@@@@@@@@@@@

Stepper motors:

A stepper motor's shaft has permanet magnets attached to it. Around the body of the

motor is a series of coils that create a magnetic field that interacts with the permanet

magnets. When these coils are turned on and off the magnetic field causes the rotor to

move. As the coils are turned on and off in sequence the motor will rotate forward or

reverse.

BACK EMF:

A motor is a machine which converts electric energy into mechanical energy. Its action is

based on the principle that when a current carrying conductor is placed in a mgnetic field,

it expieriences a mechanicalm force whose direction is given by Fleming’s left hand rule.

Fleming's left hand rule (for electric motors) shows the direction of the resultant motion

of the motor on a conductor carrying a current in a magnetic field.

The left hand is held with the thumb, index finger and middle finger mutually at right

angles.

The First finger represents the direction of the magnetic Field.

The Second finger represents the direction of the Current (in the classical direction, from

positive to negative). The Thumb represents the direction of the Thrust or resultant

Motion.

Energy conversion is not possible unless there is some opposition whose overcoming

provides the necceessary means for such conversion. In case of generator it was the

magnetic drag which provided the necessary opposition. The equivalent in the case of a

motor is called as the back emf.

As soon as the armature or the rotor starts rotating , dynamically(or motionally ) induced

emf is produced in the armature conductors. The direction of this induced emf as found

by the fleming’s right hand rule , is in direct oppposition to the applied voltage. That is

why this is known as BACK EMF or counter emf. The electrical work done in

overcoming this opposition is converted into mechanical energy developed in the

armature. Therefore, it is obvious that but for the production of this opposing emf energy

eould not have been possible.

When the armature rotates the conductors also rotate and hence cut the flux. In

accordance with the laws of electromagnetic induction, emf is induced in them whose

direction, is in oppoaition to the applied voltage. This induced emf is called back emf.

Obviously supply voltage has to drive armature current against the opposition of back

emf.

These motors also suffer from EMF, which means that once the coil is turned off it starts

to generate current because the motor is still rotating. There needs to be an explicit way

to handle this extra current in a circuit otherwise it can cause damage and affect

performance of the motor.

The ULN2003 / MC1413 is a 7-bit 50V 500mA TTL-input NPN darlington driver. This

is more than adequate to control a four phase unipolar stepper motor such as the KP4M4-

001.

It is recommended to connect a 12v zener diode between the power supply and VDD (Pin

9) on the chip, to absorb reverse (or "back") EMF from the magnetic field collapsing

when motor coils are switched off. (See Douglas W. Jones' rather more sophisticated

example)

5.3 Driving a stepper motor:

1. The four leads of the stator winding are controlled by the four bits of the 8051

port (p1.0-p1.3). However, since the 8051 lacks sufficient current to drive the

stepper motor windings, we must use a driver such as uln2003a to energize the

stator. Instead of the uln2003a, we could have used transistors as drivers.

2. However, notice that if transistors are used as drivers, we must also use diodes to

take care of inductive current generated when the coil is turned off. One reason

that the uln2003a is preferable to the use of transistors as drivers is that the

uln2003 has as internal diode to take care of back emf.

Most stepper motor circuits that are available onlne have a bunch of transistors,

Sometimes power trnsistors too quite a complicted circuit that drives you away far frm

using it. Well i felt for most robotic use the stepper motor can be driven by a simple

ULN2003 IC that costs just 12 bucks in my backyard.

While controlling the stepper motor with a embededd or distributed microoller for a

specific application, the controlling signals from the controller to the stepper motor must

be boosted up using a driven circuitry inorder to have the compatibility between them. In

the following figure, we show that the stepper motor is driven with ULN 2003 driven

circuitry.

Identify the wire : Common and windings

The following steps show the 8051 connection to the stepper motor

3. Use an ohmmeter to measure the resistance of the leads. This should identify

which COM leads are connected to which winding leads.

4. The common wire(s) are connected to positive side of the motor’s power supply.

5. To distinguish common wire from a coil-end wire is by measuring the resistance.

Resistance between common wire and coil-end wire is always half of what it is

between coil-end and coil-end wires. Just take your multimeter and check the

resistance between the wires. one wire is a common and it must bear a resistance

of 75 ohms with all the other wires then that is the common wire.This is due to the

fact that there is actually twice the length of coil between the ends and only half

from center (common wire) to the end.

@@@@@@@@@@@@@@@@@@@@@

A pulse is an electrical signal that repeats ON and OFF voltages as shown in the

illustration below. Each cycle of ON and OFF (1 cycle) is called a “pulse.”

Normally, a 5 volts is used. ON is high and OFF is low.

Figure 2.1 Pulse Train

working principle of Stepper motor:

To make a stepper motor rotate, you must constantly turn on and off the coils. If you

simply energize one coil the motor will just jump to that position and stay there resisting

change. This energized coil pulls full current even though the motor is not turning. The

stepper motor will generate a lot of heat at standstill. The ability to stay put at one

position rigidly is often an advantage of stepper motors. The torque at standstill is called

the holding torque.

Because steppers can be controlled by turning coils on and off, they are easy to control

using digital circuitry and microcontroller chips. The controller simply energizes the coils

in a certain pattern and the motor will move accordingly. At any given time the computer

will know the position of the motor since the number of steps given can be tracked. This

is true only if some outside force of greater strength than the motor has not interfered

with the motion.

When a phase winding of a stepper motor is energised with current ,a magnetic flux is

developed in the sator.the direction of this flux is determined by the “right hand rule”

which states:”if the coil is grasped in the right hand with fingers pointing in the direction

of th ecurrent in the winding (the thumb is extended at right angle to the fingers ),then the

thumb will point in the direction of the magnetic field .”

The number of times the stepper motor turns on and off depends on the number of teeth

present on the rotor and this is shown with an example in which four-step sequence is

considerd. Four-step sequence means, after completing every four steps,the rotor moves

only one tooth pitch. In this example,the rotor has only 25 teeth and so it makes 100 steps

for one complete rotation.

Figure 1 illustrates one complete rotation of a stepper motor. At position 1, we can see

that the rotor is beginning at the upper electromagnet, which is currently active (has

voltage applied to it). To move the rotor clockwise (CW), the upper electromagnet is

deactivated and the right electromagnet is activated, causing the rotor to move 90 degrees

CW, aligning itself with the active magnet. This process is repeated in the same manner

at the south and west electromagnets until we once again reach the starting position.

http://www.imagesco.com/articles/picstepper/02.html#fig1%23fig1

You may double the resolution of some motors by a process known as "half-stepping".

Instead of switching the next electromagnet in the rotation on one at a time, with half

stepping you turn on both electromagnets, causing an equal attraction between, thereby

doubling the resolution.

There are basically two types of stepper motors depending on the arrangements of the

electromagnetic coils. They are unipolar and bipolar

Unipolar:

In a unipolar stepper motor, there are four separate electromagnets. To turn the motor,

first coil "1" is given current, then it's turned off and coil 2 is given current, then coil 3,

then 4, and then 1 again in a repeating pattern. Current is only sent through the coils in

one direction; thus the name unipolar.

A unipolar stepper motor will have 5 (or 6) wires coming out of it. Four of those wires

are each connected to one end of one coil. The extra wire (or 2) is called "common" and

is connected to the other ends of all four coils. To operate the motor, the "common" wire

is connected to the supply voltage, and the other four wires are connected to ground

through transistors, so the transistors control whether current flows or not. A

microcontroller or stepper motor controller is used to activate the transistors in the right

order. these are the cheapest way to get precise angular movements.

Bipolar motor:

In a bipolar motor, there are only two coils, and current must be sent through a coil first

in one direction and then in the other direction; thus the name bipolar. Bipolar motors

need more than 4 transistors to operate them, but they are also more powerful than a

unipolar motor of the same weight. To be able to send current in both directions,

engineers can use an H-bridge to control each coil or a step motor driver chip.this type of

motor is not regularly used for robotics.

Bipolar controllers can switch between supply voltage, ground, and unconnected.

Unipolar controllers can only connect or disconnect a cable, because the voltage is

already hard wired. Unipolar controllers need center-tapped windings.

It is possible to drive unipolar stepper motors with bipolar drivers. The idea is to connect

the output pins of the driver to 4 transistors. The transistor must be grounded at the

emitter and the driver pin must be connected to the base. Collector is connected to the

coil wire of the motor.

Stepper motor advantages and disadvantages

Advantages:

1. the rotation angle of the motor is proportional to the input pulse.

2. the motor has full torque at standstill(if the windings are energised)

http://en.wikipedia.org/wiki/H-bridge

http://en.wikipedia.org/wiki/Microcontroller

3. precisen positioning and repeatability of movement since good stepper motors

have an accuracy of 3-5% of a step and this error is non cumulative from one step

to the next.

4. excellent response to starting/stopping/reversing.

5. very reliable since they are no contact brushes in the motor. Therefore the life of

the motor is simply dependent on the life of the bearing.

6. the motos response to the digital input pulses provides open-loop control,making

the motor simpler and less costly to control.

7. it is possilble to achieve very slow speed synchronous ratation with a load that is

directly coupled to the shaft .

8. a wide range of rotational speeds can be realized as the speed is proportional to

the frequency of the input pulses.

Disadvantages:

1.resonances can occur if not properly controlled

2.not easy to operate at extremely high speeds.

3. This motor can also be heated at standing because of the torque required to hold it in

position.

When to use stepper motors:

Computer-controlled stepper motors are one of the most versatile forms of positioning

systems, particularly when digitally controlled as part of a servo system. Stepper motors

can be used to advantage where you need to control rotation angle,position and

synchronism. Stepper motors are used in floppy disk drives, flatbed scanners, and

typewriters, printers-y plotters, milling machines, valve actuators, medical equipment, fax

machines, automotives and many more devices.

5.4 APPLICATIONS:

Stepper motors are used for operation control in computer peripherals, textile industry, IC

fabrication and robotics etc. applications requiring incremental motion are typewriters,

line printers, tape drives, numerically-controlled machine tools, process control systems

and X-Y plotters.. Stepper motors also perform countless tasks outside the computer

industry. It includes commercial, military and medical applications where these motors

perform such functions as mixing, cutting, striking, metering, blending and purging. They

also take part in the manufacture of packed food stuffs, commercial end-products and

even the production of science fiction movies

KEYPAD :-

At the lowest level, keyboards are organized in a matrix of row and columns. The

CPU access both rows and columns through ports therefore

,with two bit ports, an 4x4 matrix of keys can be connected to the microprocessor. When

a key is pressed, a row and column make contact; otherwise there is no connection

between rows and columns.

Figure shows 4x4 matrixes connected to two ports. The rows are connected

to out port and columns are connected to an input port. If no key has been

pressed, reading the port will yield 1s for all column since all they are connected to high

(vcc).if all the rows are grounded and key is pressed provides the path to the ground. It is

the function of the microcontroller to scan the keyboard continuously to detect and

identify the key is pressed.

LCD

8.LCD:-

To send any of the commands from given table to the lcd, make pin RS =0.For

data, make RS=1.then send a high to low pulse to the E pin to enable the internal latch of

the LCD. As shown in figure for LCD connections.

Pin number

Symbol Level I/O Function

1 Vss - - Power supply (GND)

2 Vcc - - Power supply (+5V)

3 Vee - - Contrast adjust

4 RS 0/1 I0 = Instruction input1 = Data input

5 R/W 0/1 I0 = Write to LCD module1 = Read from LCD module

6 E 1, 1->0 I Enable signal

7 DB0 0/1 I/O Data bus line 0 (LSB)

8 DB1 0/1 I/O Data bus line 1






14 DB7 0/1 I/O Data bus line 7 (MSB)

Table 2.2., Pin assignment for > 80 character displays

Pin number


1 DB7 0/1 I/O Data bus line 7 (MSB)







8 DB0 0/1 I/O Data bus line 0 (LSB)

9 E1 1, 1->0 IEnable signal row 0 & 1 (1stcontroller)

10 R/W 0/1 I0 = Write to LCD module1 = Read from LCD module

11 RS 0/1 I0 = Instruction input1 = Data input

12 Vee - - Contrast adjust

13 Vss - - Power supply (GND)

14 Vcc - - Power supply (+5V)

15 E2 1, 1->0 IEnable signal row 2 & 3 (2ndcontroller)

16 n.c.

Table 2.4. Bit names

Bit name

Setting / Status

I/D 0 = Decrement cursor position1 = Increment cursor position

S 0 = No display shift 1 = Display shift

D 0 = Display off 1 = Display on

C 0 = Cursor off 1 = Cursor on

B 0 = Cursor blink off1 = Cursor blink on

S/C 0 = Move cursor 1 = Shift display

R/L 0 = Shift left 1 = Shift right

DL 0 = 4-bit interface 1 = 8-bit interface

N 0 = 1/8 or 1/11 Duty (1 line) 1 = 1/16 Duty (2

Table 2.2., Pin assignment for > 80 character displays

Pin number


lines)

F 0 = 5x7 dots 1 = 5x10 dots

BF 0 = Can accept instruction1 = Internal operation in progress

KEIL SOFTWARE

9.KEIL SOFTWARE

1. SOFTWARE DESCRIPTION:

1. Click on the Keil uVision Icon on Desktop

2. The following fig will appear

3. Click on the Project menu from the title bar

4. Then Click on New Project

5. Save the Project by typing suitable project name with no extension in u r own

folder sited in either C:\ or D:\

6. Then Click on Save button above.

7. Select the component for u r project. i.e. Atmel……

8. Click on the + Symbol beside of Atmel

9. Select AT89C51 as shown below

10. Then Click on “OK”

11. The Following fig will appear

12. Then Click either YES or NO………mostly “NO”

13. Now your project is ready to USE

14. Now double click on the Target1, you would get another option “Source

group 1” as shown in next page.

15. Click on the file option from menu bar and select “new”

16. The next screen will be as shown in next page, and just maximize it by double

clicking on its blue boarder.

17. Now start writing program in either in “C” or “ASM”

18. For a program written in Assembly, then save it with extension “. asm” and

for “C” based program save it with extension “ .C”

19. Now right click on Source group 1 and click on “Add files to Group Source”

20. Now you will get another window, on which by default “C” files will appear.

21. Now select as per your file extension given while saving the file

22. Click only one time on option “ADD”

23. Now Press function key F7 to compile. Any error will appear if so happen.

24. If the file contains no error, then press Control+F5 simultaneously.

25. The new window is as follows

26. Then Click “OK”

27. Now Click on the Peripherals from menu bar, and check your required port as

shown in fig below

28. Drag the port a side and click in the program file.

29. Now keep Pressing function key “F11” slowly and observe.

You are running your program successfully

10.CIRCUIT DIAGRAM

11.WORKING PRINCIPLE

12. SOURCE CODE:

#include<reg51.h>

#include<string.h>

#define COL P2 //LOWER PINS OF PORT 2 :0,1,2

#define ROW P3 //LOWER PINS OF PORT 3 :0,1,2,3

sfr LCDDATA=0X90;//PORT 1;

sbit RS=P2^5;

sbit RW=P2^6;

sbit EN=P2^7;

sbit BUZZER=P2^3;

KEYPAD1();

lcdcmd(unsigned char);

lcddata();

serail();

lcddata1();

lcddata2();

lcddata3();

lcddata4();

lcddata5();

lcddata6(unsigned char);

lcdready();

strngcmp();

stepmotor();

delay(unsigned int);

int i,j,r ;

char passwd[4]="1234";

unsigned char keypad[4][3]=

{'1', '2', '3',

'4', '5', '6',

'7', '8', '9',

'*', '0', '#'};

char a[5];

main()

{

BUZZER=0;

lcdcmd(0x38);

lcdcmd(0x0E);

lcdcmd(0x01);

lcdcmd(0x06);

lcdcmd(0x81);

lcddata();

while(1)

{

serail();

strngcmp();

}//while(1)

}// MAIN CLOSE...........

///////////////////////////////////////////////////////////////////

strngcmp()

{

if((strcmp(passwd,a) ==0))

{

lcddata2();

lcdcmd(0xc3);

lcddata4();

stepmotor();

}

else

{

lcddata3();

lcdcmd(0xc3);

lcddata5();

BUZZER=1;

}

}// closing strcmp

serail()

{

for(i=0;i<4;i++)

{

a[i]=KEYPAD1();

lcddata6('*');

}

}

////////////////////////////////////////////////

lcddata()

{

unsigned char s;

unsigned char temp[14]="ENTER PASSWORD";

lcdready();

for(s=0;s<14;s++)

{

LCDDATA=temp[s];

RS=1;

RW=0;

EN=1;

delay(1);

11EN=0;

}

}

//////////////////////////////////////////////////////////////////

//////////////////////////////////////////////////////////////////

lcddata2()

{

unsigned char s;

unsigned char temp[12]=" VALID ";

lcdready();

for(s=0;s<12;s++) //DATA2

{

LCDDATA=temp[s];

RS=1;

RW=0;

EN=1;

delay(1);

EN=0;

}

}

///////////////////////////////////////////////////////////////////

lcddata3()

{

unsigned char s;

unsigned char temp[12]=" IN VALID ";

lcdready();

//DATA3

for(s=0;s<12;s++)

{

LCDDATA=temp[s];

RS=1;

RW=0;

EN=1;

delay(1);

EN=0;

}

}

/////////////////////////////////////////////////////////////////

lcddata4()

{

unsigned char s;

unsigned char temp[12]=" WELCOME ";

lcdready();

//DATA4

for(s=0;s<12;s++)

{

LCDDATA=temp[s];

RS=1;

RW=0;

EN=1;

delay(1);

EN=0;

}}

////////////////////////////////////////////////////////////////////////////

lcddata5()

{

unsigned char s;

unsigned char temp[12]=" SORRY ";

lcdready();

for(s=0;s<12;s++)

{ //DATA5

LCDDATA=temp[s];

RS=1;

RW=0;

EN=1;

delay(1);

EN=0;

}}

//////////////////////////////////////////////////////////////

lcdcmd(unsigned char value)

{

lcdready();

LCDDATA=value;

RS=0;

RW=0;

EN=1;

delay(1);

EN=0;

return;

}

//////////////////////////////////////////////////

lcdready()

{

BUSY=1;

RS=0;

RW=1;

while(BUSY==1)

{

EN=0;

delay(1);

EN=1;

}

return;

}

/////////////////////////////////////////////////////////////

lcddata6(unsigned char value)

{

LCDDATA=value;

RS=1;

RW=0;

EN=1;

delay(1);

EN=0;

delay(1);

return;

}

/////////////////////////////////////////////////////////////

delay(unsigned int time)

{

unsigned int i,j;

for(i=0;i<time;i++)

for(j=0;j<1275;j++);

}

KEYPAD1()

{

char colloc, rowloc;

COL=0xFF;

while(1)

{

do

{

ROW=0x00;

colloc=COL;

colloc&=0x07;

} while(colloc!=0x07);

do

{

do

` {

delay(1);

colloc=COL;

colloc &= 0x07;

} while(colloc==0x07);

delay(1);

colloc=COL;

colloc&=0x07;

} while(colloc==0x07);

while(1)

{

ROW=0xFE;

colloc=COL;

colloc&=0x07;

if (colloc != 0x07)

{

rowloc=0;

break;

}

ROW=0xFD;

colloc=COL;

colloc&=0x07;

if (colloc != 0x07)

{

rowloc=1;

break;

}

ROW=0xFB;

colloc=COL;

colloc&=0x07;

if (colloc != 0x07)

{

rowloc=2;

break;

}

ROW=0xF7;

colloc=COL;

colloc&=0x07;

if (colloc != 0x07)

{

rowloc=3;

break;

}

}

if (colloc== 0x06)

return(keypad[rowloc][0]);

else if(colloc==0x05)

return(keypad [rowloc][1]);

else

return(keypad [rowloc][2]);

}

}

stepmotor()

{

P0=0X11;

delay(20);

P0=0X22;

delay(20);

P0=0X44;

delay(20);

P0=0X88;

delay(20);

P0=0X11;

delay(20);

P0=0X22;

delay(20);

P0=0X44;

delay(20);

P0=0X88;

delay(20);

P0=0X11;

delay(20);

P0=0X22;

delay(20);

P0=0X44;

delay(20);

P0=0X88;

delay(20);

P0=0X44;

delay(20);

P0=0X22;

delay(20);

P0=0X11;

delay(20);

P0=0X88;

delay(20);

P0=0X44;

delay(20);

P0=0X22;

delay(20);

P0=0X11;

delay(20);

P0=0X88;

delay(20);

P0=0X44;

delay(20);

P0=0X22;

delay(20);

P0=0X11;

delay(20);

}

13. CONCLUSION

Embedded systems are emerging as a technology with high potential. In the past

decades micro processor based embedded system ruled the market. The last decade

witnessed the revolution of Microcontroller based embedded systems. This project

basically deals with how many number of persons are in the room very accurately with

the help of Microcontroller. With regards to the requirements gathered the manual work

and the complexity in counting can be achieved with the help of electronic devices.

14.FUTURE SCOPE

This system is a rapidly growing field and there are new and improved

strategies popping up all the time. For the most part these systems are all built around the

same basic structure, a central box that monitors several detectors and perimeter guards

and sounds an alarm when any of them are triggered.

This system is best for guiding the perimeter of a house or a business center

the points where an intruder would enter the building. In this system IR sensor is used to

detect the intrusion. Similarly the vibration and temperature sensors recognize vibration

disturbances and accidental fires respectively.

This project provides an efficient and economical security system. This

system finds applications in industries, banks and homes.

Incorporating the features discussed below can further enhance the system

This system can detect intrusion only at discrete points. This system

detection feature can be extended to scanning a complete area. Thus the

intrusion into the building can be detected with much more efficiently.

The redialing feature can also be incorporated such that if the call is not put

forward the first time, the auto dialer will dial the same number until the call

is successfully completed.

A pre-recorded voice message can delivered to the owner notifying him about

the intrusion into the premises.

The addition of the above discussed advancements certainly builds this project

into a much flexible and reliable security system.

15.BIBLOGRAPHY

1. The 8051 Microcontroller and Embedded Systems By Muhammad Ali Mazidi

2. Fundamentals Of Embedded Software By Daniel W Lewis

3..www.howsstuffworks.com

4. www.alldatasheets.com

5. www.electronicsforu.com

6. www.knowledgebase.com

7.www.8051 projectsinfo.com 8.Datasheets of Microcontroller AT89C52

9. Datasheets of 555 timer

10. Datasheets of TSAL 6200

11. Datasheets of TSOP 1356

12. Datasheets of BC 547

13. Datasheets of DTMF Generator UM 95089

http://www.knowledgebase.com/

http://www.electronicsforu.com/

http://WWW.howsstuffworks.com/

Documents

Digital Code Locking System