Door Security Monitoring System Computer Science Essay

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This FYP contains three main parts. Firstly, its about Peripheral interface controller in known device that can control the other devices using a program that been written into that PIC. Selected PIC for this project is PIC16F877A. This PIC has pin out which can be obtained in a different package, for example 40-dip dual in line package. This PIC has 5 ports which are port A, B, C, D and E.

Definition of door security monitoring system.

A lock is a mechanical fastening device which may be used on a door, vehicle, or container, restricting access to the area or enclosed property. Commonly, it can be released by using a key, keycard, RFID signal, but for this FYP it comes out with user need to key in the code or password. Besides, it also combines with transmitter, receiver, PIC, magnetic lock, electronic components and programming.

PIC Microcontroller 16F877A

Making PIC based instrument and controlled has to do with learning how to combine the various capabilities that single chip microcontroller units provide the utilizing a coherent set of interactive function that serve the purpose we have in mind [1].

Microcontrollers must contain at least two primary components - random access memory (RAM), and an instruction set. RAM is a type of internal logic unit that stores information temporarily. RAM contents disappear when the power is turned off. While RAM is used to hold any kind of data, some RAM is specialized, referred to as registers. The instruction set is a list of all commands and their corresponding functions. During operation, the microcontroller will step through a program (the firmware). Each valid instruction set and the matching internal hardware that differentiates one microcontroller from another.

Most microcontrollers also contain read-only memory (ROM), programmable read-only memory (PROM), or erasable programmable read-only memory (EPROM). Al1 of these memories are permanent, they retain what is programmed into them even during loss of power. They are used to store the firmware that tells the microcontroller how to operate. They are also used to store permanent lookup tables. Often these memories do not reside in the microcontroller; instead, they are contained in external ICs, and the instructions are fetched as the microcontroller runs. This enables quick and low-cost updates to the firmware by replacing the ROM.

Where would a microcontroller be without some way of communicating with the outside world. This job is left to input/output (I/O) port pins. The number of I/O pins per controllers varies greatly, plus each I/O pin can be programmed as an input or output (or even switch during the running of a program). The load (current draw) that each pin can drive is usually low. If the output is expected to be a heavy load, then it is essential to use a driver chip or transistor buffer.

Most microcontrollers contain circuitry to generate the system clock. This square wave is the heartbeat of the microcontroller and all operations are synchronized to it. Obviously, it controls the speed at which the microcontroller functions. All that needed to complete the clock circuit would be the crystal or RC components.

To summarize, a microcontroller contains (in one chip) two or more of the following elements in order of importance:

RAM

I/O ports

Clock generator

Reset function

Serial port

Interrupts

Timers

Analog-to-digital converters

Digital-to-analog converters

Transmitter and Receiver 315 MHz

Transmitter and receiver required power to transmit the conversion between two parties on the line to a receiver immediately a conversion begins. Frequency operation is 315 MHz crystal controlled fm narrow. This devices work as a communication between two devices such as device at locker and others at computer. The receiver has a sensitivity of 3μV. It operates from 4.5 to 5.5 volts - DC, and has both linear and digital outputs. For maximum range, it be recommended antenna length to be 1/4 wave of the frequency. That means, for 315 MHz, the antenna length is approximately 17cm long.  To convert from centimeters to inches multiply by 0.3937.   Indoors, the range is approximately 200 foot [6]. The TLP transmitter accepts both linear and digital inputs can operate from 1.5 to 12 Volts-DC, and makes building a miniature hand-held RF transmitter very easy. Normally, RF module can transmit signal connect to decoder HT12D and encoder HT12E but there some calculation to calculate frequency transmit and receive [9]. Refer appendix C.

Table 1: Receiver 315 MHz specification

No.

Specifications

RF Receiver

1.

Operating Voltage

5.0V ± 0.5V

2.

Operating Current

≤5.5mA @5.0V

3.

Operating Principle

Monolithic super heterodyne receiving

4.

Modulation

OOK/ASK

5.

Frequency

315MHz, 433.92MHz

6.

Bandwidth

2MHz

7.

Sensitivity

-100dBm

8.

Rate

<9.6Kbps (315MHz @-95dBm)

9.

Data Output

TTL

10.

Antenna Length

24cm (315MHz), 18cm (433.92MHz)

Table 2: Transmitter 315 MHz specification

No.

Specifications

RF Transmitter Module

1.

Operating Voltage

3V to 12 V

2.

Operating Current

Max ≤ 40mA (12V), Min ≤ 9mA (3V)

3.

Oscillator

SAW (Surface Acoustic Wave) oscillator

4.

Frequency

315MHz~433.92MHz

5.

Frequency error

±150kHz(max)

6.

Modulation

ASK/OOK

7.

Transfer Rate

≤10Kbps

8.

Transmitting power

25mW (315MHz@12V)

9.

Antenna Length

24cm (315MHz), 18cm (433.92MHz)

Figure 1: Calculation resistor oscillator

Keypad

For keypad wiring, keypads pins need to pull up or pull down to avoid floating case happen. Pull up normally connect to 5V and pull down is connect to ground. 4x4 Keypad pin can directly connect to microcontroller or keypad decoder IC for decodes purpose. However, DIY scanning of keypad consumes a lot of understanding in programming and more program space. The better way to interface a keypad to the PIC is to use a keypad encoder in between the keypad and the microcontroller [11]. One of the Keypad Encoder is the MMC74C922. Refer appendix C.

Figure 2: Internal keypad connections

Table 3: Truth table Keypad Encoder MMC74C922

Switch Position

0 1 2 3 4 5 Y1,X1 Y1,X2 Y1,X3 Y1,X4 Y2,X1 Y2,X2

6 7 8 9 10 Y2,X3 Y2,X4 Y3,X1 Y3,X2 Y3,X3

11Y3,X4

D

A

A

0

1

0

1

0

1

0

1

0

1

0

1

T

B

0

0

1

1

0

0

1

1

0

0

1

1

A

C

0

0

0

0

1

1

1

1

0

0

0

0

O

D

0

0

0

0

0

0

0

0

1

1

1

1

U

E (Note 1)

0

0

0

0

0

0

0

0

0

0

0

0

Switch Position

12 Y4,X1

13 Y4,X2

14 Y4,X3

15 Y4,X4

16 Y5(Note 1), X1

17 Y5 (Note 1), X2

18 Y5 (Note 1), X3

19 Y5 (Note 1), X4

D

A

A

0

1

0

1

0

1

0

1

T

B

0

0

1

1

0

0

1

1

A

C

1

1

1

1

0

0

0

0

O

D

1

1

1

1

0

0

0

0

U

E (Note 1)

0

0

0

0

1

1

1

1

RS 232 serial communication

RS232 is a popular communications protocol for connecting modems and data acquisition devices to computers. RS232 devices can be plugged straight into the computer's serial port (also known as the COM or Comms port). Examples of data acquisition devices include GPS receivers, electronic balances, data loggers, temperature interfaces and other measurement instruments.

A nine pin D plug has become the standard fitting for the serial ports of PCs. The pin connections used are as shown in Table 4. The connector on the PC has male pins, therefore the mating cable needs to terminate in a DB9/F (Female pin) connector [12].

Table 4: RS232 pin assignments (DB9 PC signal set)

Pin 1

Input

DCD

Data Carrier Detect

Pin 2

Input

RXD

Received Data

Pin 3

Output

TXD

Transmitted Data

Pin 4

Output

DTR

Data Terminal Ready

Pin 5

Signal Ground

Pin 6

Input

DSR

Data Set Ready

Pin 7

Output

RTS

Request To Send

Pin 8

Input

CTS

Clear To Send

Pin 9

Input

RI

Ring Indicator

Normal PC hardware might well run with just Tx, Rx and Ground connected, most driver software will wait forever for one of the handshaking lines to go to the correct level. Depending on the signal state it might sometimes work, other times it might not. The reliable solution is to loop back the handshake lines if they are not used.

Figure 3: PC serial connector

Assembly language

Assembly programming language as it applies to embedded microcontroller applications. This programming needed programmer for declaring variables and constant do loops, testing the logic analyzer. In c programming there are several types of loops. Next, the important part is software to interface with PIC. The software used is assembly programming. Assembly compiler is software to write, simulate and burn the program into PIC. To ensure written programming worked or not, it can combine with software Proteus. From this software, the program can be simulated with circuit [2].

Visual Basic Language

Visual Basic is designed to allow the program run under the windows without the complexity generally associated with windows programming [3]. The designed screen can hold standard windows button such as command buttons, check boxes, option buttons, text boxes, and so on. Each of these windows object, operates as expected, producing a "standard" windows user interface.

Visual Basic that has recently appeared as one of the most popular programming language is chosen. It provided standard window object and graphic user interface that will make the program become user friendly.

Magnetic Lock

A magnetic lock is a simple locking device that consists of an electromagnet and armature plate. By attaching the electromagnet to the door frame and the armature plate to the door, a current passing through the electromagnet attracts the armature plate holding the door shut. Unlike an electric strike a magnetic lock has no interconnecting parts and is therefore not suitable for high security applications because it is possible to bypass the lock by disrupting the power supply [4].

Figure 4: Electronically- controlled magnetic lock assembly.

Liquid Crystal Display (LCD)

LCD have a specific pin in order to display the exact from programming. It must receive data sent from microcontroller; therefore pin enables should 'high' in order to receive the data. LCD 16 x 2 is used in the project [10].

Figure 5: Connections LCD to Microcontroller

Table 5: LCD pin description

Pin Functions

Signal

No. of Lines

I/O

Device Interfaced with

Function

RS

1

I

MPU

Selects registers. 0: Instruction register (for write) Busy flag: address counter (for read) 1: Data register (for write and read)

R/W

1

I

MPU

Selects read or write. 0: Write 1: Read

E

1

I

MPU

Starts data read/write.

DB4 to DB7

4

I/O

MPU

Four high order bidirectional tristate data bus pins. Used for data transfer and receive between the MPU and the HD44780U. DB7 can be used as a busy flag.

DB0 to DB3

4

I/O

MPU

Four low order bidirectional tristate data bus pins. Used for data transfer and receive between the MPU and the HD44780U. These pins are not used during 4-bit operation.

. Conclusion

Door monitoring systems are combination of mechanical and electronic parts. By using electronics components and technology, this security system gives more benefic, easy to lock with high security and make life more comfortable to the user.

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