DESIGN AND CONSTRUCTION OF BURGLAR ALARM SYSTEM
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Applications of digital electronics were widely used in almost all areas of life: computers, automated machine control, robots, energy monitoring and control, inventory management, medical science and technology, transportation, entertainment and space exploration. The burglar alarm system would be designed to cover and monitor the whole perimeter of a building to ensure that any movement made within the protected area would be sensed and a burglar alarm would be activated. The burglar alarm system was built around a microcontroller programmed to accept a known security code with which the security system is either enabled or disabled. The microcontroller accepts the entered code and digital compares it with the registered code. The motion detection stages are implemented through the use of infra red transceivers. The infra red transmitter emits infra red rays which are detected by the photo diode placed within the line of sight of the transmitters. When motion is detected by any of the four transceivers employed to monitor the perimeter of the building, an alarm comes on to alert of a possible presence of an intruder.
Keywords: Burglar Alarm System, Microcontroller, Motion Detection, Infrared Transmitter
DESIGN AND CONSTRUCTION OF BURGLAR ALARM SYSTEM
Atoyebi, O. P. and Odewale, A. A.,
Department of Computer Science and Engineering,
Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria.
E-mail: atoscolarry[at]yahoo.com, odewaleakeem[at]yahoo.com
entering the correct six (6) digit code on a keypad into the system, the burglar alarm system comes alive. The system incorporates an anti-fiddle protection that ensures that only four trials of code entry are allowed. When the code has been incorrectly entered four times in a row, system would switch to alarm mode. In this state, all keys pressed are ignored for one minute and at the same time the buzzer will sound the alarm signal. This function thwarts any attempt by „hackers, to quickly try large numbers of codes in sequence.
In designing this project, a microcontroller would be programmed to activate an output that enables or disables the security system when the correct access code has been entered on a keypad. A buzzer would be added to provide input feedback, the number of beeps indicates whether the input has been correctly entered or not. The burglar alarm system would employ four infra red transceiver units to cover the whole perimeter of the building and when motion is sensed, a burglar alarm is enabled to alert the security agents around of the presence of a possible burglar.
I am majorly interested in this project solely because of the increasing crime rate in this country and a way of stopping the situation. Furthermore, there was a need to protect home so that users can take advantage of technological advancement even when the person concerned is not around.
2. Review of Previous Work
Development of a Simple Sound Activated Burglar Alarm System
According to Ahmed M. S, Mohammed A. S. & Agbo G. A. (2008) explained how the amplifier stage was built around an LM386 CMOS operational amplifier. The circuit arrangement is such that it can amplify an input signal up to 200 times its original value.
Once a sound that exceeds certain intensity is produced, it is picked by the microphone, amplified and sent to the latch, the latch keeps the alarm still ringing until the reset button is pressed.
Figure 1: Block diagram of sound activated burglar alarm
After testing the alarm system the following results were obtained for distances and sound intensities for which the alarm was triggered. When the microphone was also tapped the alarm was triggered.
3. System Overview
The main role of a microcontroller unit in an embedded system is to provide inexpensive, programmable logic control and interfacing to eternal devices.
According to Julio Sanchez and Maria P. Canton, in their book microcontroller programming (2007), explained microcontroller is a computer control system on a single chip. It has many electronic circuits built into it, which can decode written instruction instructions and convert them into electrical signals. The microcontroller will
then step through the instructions and execute
them one by one.
Programs written into the microcontroller are
stored in the EPROM (Electrically
Programmable Read Only Memory). This
memory is non volatile and is remember when
the power is switched off. The memory is
electrically programmed by a piece of hardware
called a programmer.
The instructions written into the microcontroller
work by moving and manipulating data in
memory locations known as user files and
registers. This memory is called RAM, Random
The overall stages involves in the design of
burglar alarm system can be divided into
subunits include the power supply, infrared
sensors, digital logic control, timing circuitry and
alarm. Figure 2 shows the block diagram of the
overall system. For implementation of burglar
alarm system there were some materials that was
used, this includes: Programmable IC,
PIC16F84A – this served as brain, the remain
materials are photodiode, LED, Resistor,
Capacitor, IC Socket, 5volt Regulator (7805),
Vero-board, List of tools used are: soldering iron,
cutter, nose pliers, multimeter, IC programmer.
Figure 2: Generalized block diagram for the burglar alarm
4. Hardware Design Consideration
Power Supply Unit
The whole design is powered with a 5V dc supply. Herein, a regulated dc voltage is obtained from the mains‟ 220VAC. A step down transformer is used to step down the 220VAC to 18VAC. The 18VAC is rectified to obtain a dc voltage require to power the digital circuitry. Since the microcontroller requires a 5-volt supply, a voltage regulator (78L05) is used to regulate the rectified, filtered 18VDC to 5VDC desired. Figure 8 shows the power supply stage for this design.
The microcontroller stage is implemented by using the popular and versatile PIC16F84A. PIC16F84 belongs to a class of 8-bit
microcontrollers of RISC architecture. It is an 18 pin dual in-line package chip. The PIC is a tiny but complete computer. It has a CPU (central processing unit), program memory (PROM), working memory (RAM), and two input-ports. it can store and retrieve data in working memory (RAM).
The program memory of the F84A consists of flash EPROM; it can be recorded and erased electrically, and it retains its contents when powered off. Program memory (FLASH)- for storing a written program.
Working memory holds the data when it's working on. There are also several special function registers each of which controls the operation of the PIC in some way.
Figure 3: Circuit diagram for the burglar alarm system
There are two input- output ports, port A
and port B, and each pin of each port can be set
individually as an input or an output. The bits of
each port are numbered, starting at 0. In output
mode, bit 4 of port A has an open collector (or
rather open drain); the rest of the outputs are
regular CMOS. The CPU treats each port as one
8-bit byte of data even though only five bits of
port A are actually brought out as pins of the IC.
PIC inputs are CMOS-compatible; PIC outputs
can drive TTL or CMOS logic chips: Each
output pin can source or sink 20mA as long as
only one pin is doing so at a time.