AUTOMATIC COLLEGE BELL
Abstract
This Project takes over the task of
Ringing of the Bell in Colleges. It replaces the Manual Switching of the Bell
in the College. It has an Inbuilt Real Time Clock (DS1307) which tracks over
the Real Time. When this time equals to the Bell Ringing time, then the Relay
for the Bell is switched on. The Bell Ringing time can be edited at any Time,
so that it can be used at Normal Class Timings as well as Exam Times. The Real
Time Clock is displayed on four 7-segment display. The Microcontroller
AT89S8252 is used to control all the Functions, it get the time through the
keypad and store it in its Memory. And when the Real time and Bell time get
equal then the Bell is switched on for a predetermined.
Introduction
This Project takes over the task of Ringing of the Bell in Colleges. It
replaces the Manual Switching of the Bell in the College. It has an Inbuilt
Real Time Clock (DS1307) which track over the Real Time. When this time Equals
to the Bell Ringing time, then the Relay for the Bell is switched On. The Bell
Ringing time can be Edited at any Time, so that it can be used at Normal Class
Timings as well as Exam Times. The Real Time Clock is displayed on four
7-segment display. The Microcontroller AT89S8252 is used to control all the
Functions, it get the time through the keypad and store it in its Memory. And
when the Real time and Bell time get equal then the Bell is switched on for a
predetermined time.
Today is
the world of atomization. Microcontrollers and embedded systems have made lot
of things automatic and easy to use.
We are
developing the system which will be used as college bell. In this system we
will use RTC for time keeping purpose .The bell will be ringing according to
time set by the keypad. LCD will be used to display current time as well as
different settings. Buzzer will turn on according to the time settings at
different intervals.
Literature survey
In early days schools and colleges had bell
which were manually operated. Therefore the lectures were stared either early
or late. Also someone must be appointed to ring the bell every time. To
overcome this drawback we are using the automatic ringing bell.
This
bell will automatically ring for the time it has been set for. We found all the
information about the microntroller in the book Mazidi. The block diagram and
the description are found from internet.
Description
The
system will consist of following components:
1) Micro
Controller: Atmel’s AT89S51 with Flash
ROM 4K and RAM 128 bytes
2) RTC DS1307
I2C protocol operated 8 pin DIP IC
3) LCD 16X2
4) Keypad
4X4 i.e. 16 keys keypad
5) Relay
6) Memory (24C04)
Criteria for choosing Microcontroller:
1. The first
& foremost criterion in choosing a Micro controller is that it must meet
the task at hand efficiently & cost effectively. In analyzing the needs of
a Micro controller based project, we must first see whether an 8-bit, or
16-bit, or 32-bit Micro controller can best handle the computing needs of the
task most effectively. Among other considerations in the category are:
·
Speed: What is the highest speed that the Micro
controller supports?
·
Packaging: Does it comes in 40-pin DIP (dual in
line package) or a QFP (quad flat package) or some other packaging format? This
is important in terms of space, assembling & prototyping the end product.
·
Power consumption: This is especially critical
for battery-powered products.
·
The amount of RAM & ROM on chip.
·
The number of I/O pins & the timer on the
chip.
·
How easy it is to upgrade to higher-performance
of lower power consumption versions.
·
Cost per unit: This is important in terms of the
final cost of the product in which a Micro controller is used. For example,
there are Micro controllers that cost 50 cents per unit when purchased 1,00,000
units at a time.
2. The second criterion in choosing a micro controller is how easy it is
to develop products around it. Key considerations include the availability of
an assembler, debugger, a code – efficient c language compiler, emulator,
technical support, and both in-house and outside expertise.
AT89c51 MICROCONTROLLER - Description
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.
Pin diagram and pin description:
|
Pin
Number
|
Description
|
|
1
- 8
|
P1.0
- P1.7 - Port 1
|
|
9
|
RST
- Reset
|
|
10
- 17
|
P3.0
- P3.7 - Port 3
|
|
18
|
XTAL2
- Crystal
|
|
19
|
XTAL1
- Crystal
|
|
20
|
GND
- Ground
|
|
21
- 28
|
P2.0
- P2.7 - Port 2
|
|
29
|
PSEN
- Program Store Enable
|
|
30
|
ALE
- Address Latch Enable
|
|
31
|
EA
- External Access Enable
|
|
32
- 39
|
P0.7
- P0.1 - Port 0
|
|
40
|
Vcc
- Positive Power Supply
|
Real time clock(RTC):
A
real-time clock (RTC) is a computer clock (most
often in the form of an integrated circuit) that keeps track of the current time.
A Real-Time-Clock (RTC) is, as the name suggests, a clock which keeps
track of time in a "real mode." While there are a number of 8051-compatible
microcontrollers that have built-in, accurate real-time clocks (especially from
Dallas Semiconductor), some simple applications may benefit from a software RTC
solution that uses the built-in capabilities of an 8051 microcontroller. RTCs
are present in almost any electronic device which needs to keep accurate time.
Purpose
- Low
power consumption (important when running from alternate power)
- Frees
the main system for time-critical tasks
- Sometimes
more accurate than other methods
Power source
RTCs often have an alternate
source of power, so they can continue to keep time while the primary source of
power is off or unavailable. This alternate source of power is normally a
lithium battery
Optocoupler
There
are many situations where signals and data need to be transferred from one
subsystem to another within a piece of electronics equipment, or from one piece
of equipment to another, without making a direct ohmic electrical connection.
Often this is because the source and destination are (or may be at times) at
very different voltage levels, like a microprocessor which is operating from 5V
DC but being used to control a triac which is switching 240V AC. In such
situations the link between the two must be an isolated one, to protect the microprocessor
from overvoltage damage. Relays can of course provide this kind of isolation,
but even small relays tend to be fairly bulky compared with ICs and many of today’s
other miniature circuit components. Because they.re electro-mechanical, relays
are also not as reliable and only capable of relatively low speed operation.
Where small size, higher speed and greater reliability are important, a much
better alternative is to use an optocoupler.
Optocoupler
are essentially digital or switching devices, so they.re best for transferring
either on-off control signals or digital data. Analog signals can be
transferred by means of frequency or pulse-width modulation.
How they are used
Basically
the simplest way to visualize an optocoupler is in terms of its two main
components: the input LED and the output transistor or diac. As the two are
electrically isolated, this gives a fair amount of flexibility when it comes to
connecting them into circuit. All we really have to do is work out a convenient
way of turning the input LED on and off, and using the resulting switching of
the phototransistor/diac to generate an output waveform or logic signal that is
compatible with our output circuitry.
Power supply
Power supply is a supply of electrical
power. A device or system that supplies electrical or other types of energy to
an output load or group of loads is called a power supply unit or PSU. There are many types of power supply. Most are designed to convert
high voltage AC mains electricity to a suitable low voltage supply for
electronics circuits and other devices. A power supply can by broken down into a series of blocks, each of which performs a particular
function.
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