22-12-2012, 04:35 PM
GSM Based Control System
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Introduction to Project
“GSM based Control System” implements the emerging applications of the GSM
technology. Using GSM networks, a control system has been proposed that will act as an
embedded system which can monitor and control appliances and other devices locally
using built-in input and output peripherals.
Remotely the system allows the user to effectively monitor and control the house/office
appliances and equipments via the mobile phone set by sending commands in the form of
SMS messages and receiving the appliances status. The main concept behind the project
is receiving the sent SMS and processing it further as required to perform several
operations. The type of the operation to be performed depends on the nature of the SMS
sent. The principle in which the project is based is fairly simple. First, the sent SMS is
stored and polled from the receiver mobile station and then the required control signal is
generated and sent to the intermediate hardware that we have designed according to the
command received in form of the sent message.
We have selected a particular Nokia mobile set (Nokia 3310) for our project. The
messages are sent from the mobile set that contain commands in written form which are
then processed accordingly to perform the required task. A microcontroller based system
has been proposed for our project. There are several terminologies that are used
extensively throughout this project report.
Background
The new age of technology has redefined communication. Most people nowadays have
access to mobile phones and thus the world indeed has become a global village. At any
given moment, any particular individual can be contacted with the mobile phone. But the
application of mobile phone can not just be restricted to sending SMS or starting
conversations. New innovations and ideas can be generated from it that can further
enhance its capabilities. Technologies such as Infra-red, Bluetooth, etc which has
developed in recent years goes to show the very fact that improvements are in fact
possible and these improvements have eased our life and the way we live. Remote
management of several home and office appliances is a subject of growing interest and in
recent years we have seen many systems providing such controls.
These days, apart from supporting voice calls a mobile phone can be used to send text
messages as well as multimedia messages (that may contain pictures, graphics,
animations, etc). Sending written text messages is very popular among mobile phone
users. Instant messaging, as it is also known, allows quick transmission of short messages
that allow an individual to share ideas, opinions and other relevant information. We have
used the very concept to design a system that acts a platform to receive messages which
in fact are commands sent to control different appliances and devices connected to the
platform. We have designed a control system which is based on the GSM technology that
effectively allows control from a remote area to the desired location. The application of
our suggested system is immense in the ever changing technological world. It allows a
greater degree of freedom to an individual whether it is controlling the household
appliances or office equipments.
Problem Statement
Technology has advanced so much in the last decade or two that it has made life more
efficient and comfortable. The comfort of being able to take control of devices from one
particular location has become imperative as it saves a lot of time and effort. Therefore
there arises a need to do so in a systematic manner which we have tried to implement
with our system. The system we have proposed is an extended approach to automating a
control system.
With the advancement and breakthroughs in technology over the years, the lives of
people have become more complicated and thus they have become busier than before.
With the adoption of our system, we can gain control over certain things that required
constant attention. The application of our system comes in handy when people who forget
to do simple things such as turn ON or OFF devices at their home or in their office, they
can now do so without their presence by the transmission of a simple text message from
their mobile phone. This development, we believe, will ultimately save a lot of time
especially when people don’t have to come back for simple things such as to turn
ON/OFF switches at their home or at their office once they set out for their respective
work.
Description:
The figure shown above is the simple block diagram of our project. It is a simple
illustration of how we have implemented our project and the various parts involved in it.
From the above representation, the first Mobile station is used as a transmitting section
from which the subscriber sends text messages that contain commands and instructions to
the second mobile station which is based on a specific area where our control system is
located. The mobile phone as indicated in the block diagram is a Nokia 3310 mobile set.
The received SMS message is stored in the SIM memory of the phone and then extracted
by the microcontroller and processed accordingly to carry out specific operations. The
relay driver (BUFFER ULN2003) is used to drive the relay circuits which switches the
different appliances connected to the interface. The LCD is used to indicate the status of
the operation performed by the microcontroller and also its inclusion makes the overall
system user-friendly.
Scopes and Purpose of System Specification
The system specification shows the description of the function and the performance of
system and the user. The scope of our project “GSM Based control system” is immense.
The future implications of the project are very great considering the amount of time and
resources it saves. The project we have undertaken can be used as a reference or as a base
for realizing a scheme to be implemented in other projects of greater level such as
weather forecasting, temperature updates, device synchronization, etc. The project itself
can be modified to achieve a complete Home Automation system which will then create a
platform for the user to interface between himself and the household.
Major Constraints
Along the course of project completion we encountered various problems and obstacles.
Not everything that we had planned went smoothly during the project development span.
Also we had a limited amount of time for its completion so we were under a certain
amount of pressure as well. We had to start from the research phase at the beginning and
needed to gain knowledge on all the devices and components that we had intended to use
for our project. Other phases of the project included coding, debugging, testing,
documentation and implementation and it needed certain time for completion so we really
had to manage the limited time available to us and work accordingly to finish the project
within the schedule.
ATMEL Micro-controller
The AT89C52 is a low-power; high performance CMOS 8-bit microcomputer with 8K
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 80C51 and 80C52 instruction set and pinout. The
on-chip Flash allows the program memory to be reprogrammed in-system or by a
conventional nonvolatile memory programmer. By combining a versatile 8-bit CPU with
Flash on a monolithic chip, the Atmel AT89C52 is a powerful microcomputer which
provides a highly-flexible and cost-effective solution to many embedded control
applications.
Temperature Sensor
The two main types of semiconductor temperature sensors are temperature sensitive
voltage sources and temperature-sensitive current sources. An example of the first type is
the National LM35. The voltage output from this circuit increases by 10 mV for each
degree centigrade that its temperature is increased. If the output is connected to a
negative reference voltage Vs, the sensor will give a meaningful output for temperature
range of -55 to +150 degree centigrade. The output is adjusted to 0V for 0 degree
centigrade. The output voltage can be amplified to give the voltage range we need for a
particular application. The accuracy of this device is about 1 degree centigrade.
A thermocouple junction made of iron and constantan, commonly called a J
thermocouple, has a useful temperature range of about -184 to 760 degree centigrade.
Thermocouples can be made small, rugged and stable, however, they have problems like
the output is very small and must be amplified a great deal to bring it up into range where
it can drive an A/D converter. So, we used LM35 in our system.
The LM35 is an integrated circuit sensor that can be used to measure temperature with an
electrical output proportional to the temperature (in deg Celsius). LM35 temperature
sensor can measure more accurately than using a thermistor. The LM35 generates a
higher output voltage than thermocouples and may not require that the output voltage be
amplified. It has an output voltage that is proportional to the Celsius temperature. The
scale factor is 0.01V/deg Celsius. Another important characteristic of LM35 is that it
draws only 60 micro amps from its supply and possesses a low self heating capability.
The sensor self heating causes less than 0.1 deg Celsius temperature rise in still air.