LPG Gas Detector and alerting using GSM Module
Abstract:
LPG gas detection projects main idea is to implement security system for detecting leakage
of gas in closed environment. In this project gas leakage is identified by using sensors which works
only in closed environment. In present situation there are many cases related to gas leakage which
cause innocent people lives and property damage. Implementing this application can be useful for
companies, houses, which can save lives of people.
The presence of dangerous LPG leakage in the cars, service station or in the storage tank
environment can be detected using the Ideal Gas Sensor. This unit can be easily integrated into a
unit that can sound an alarm or give a visual suggestion of the LPG concentration. The sensor has
both admirable sensitivity and rapid response time. This sensor can also be used to sense other
gases like iso-butane, propane, LNG and even cigarette smoke.
The output of the sensor goes LOW as soon as the LPG sensor senses any gas leakage from the
storage. This is detected by the microcontroller and the LED & buzzer is turned ON. After the delay
of few milliseconds, the exhaust fan is also turned ON for throwing the gas out and it continues
sending message as ‘GAS LEAKAGE’ to a mobile number which is pre-defined.
Block Diagram :
Switch
MQ6
Power, clock
LCD Display
Reset
Gas Sensor
Signal
conditi
on
AVR-controller
Relay driver
RS 232
INTERFACE
Theft Sensor
Reset
GSM Modem
Alarm
exhaust fan
Relay
Relay
Block Diagram :
1. Gas sensor : MQ-6 Gives analog output as per concentration of combustible gas in air. Used in
gas leakage detecting equipments for detecting of LPG, iso-butane, propane, LNG combustible
gases. The sensor does not get trigger with the noise of alcohol, cooking fumes and cigarette
smoke.
2. Theft Sensor
3. SCHEMATICS - TACTILE BUMP SENSOR CIRCUIT
4.
5. Tactile Bump Sensors are great for collision detection, but the circuit itself also works fine for
user buttons and switches as well. There are many designs possible for bump switches, often
depending on the design and goals of the robot itself. But the circuit remains the same. They
usually implement a mechanical button to short the circuit, pulling the signal line high or low. An
example is the microswitch with a lever attached to increase its range, as shown above.
6. There are several versions below, depending on how you plan to use the circuit and your
available switches. For the resistor use a very high value, such as 40kohms.
7. Tactile Bump Sensor Circuits
Voltage
goes
high
with contact
Voltage
goes
with contact
low
More efficient switch for 3 lead switches
(use for microswitches)
Introduction :
LPG gas is supplied in pressurized steel cylinders. As this gas is heavier than air, when it
leaks from a cylinder it flows along floor and tends to settle in low spots such as a basement. This
can cause fire or suffocation if not dealt with. Here is a circuit that detects the leakage of LPG gas
and alerts the user through audio-visual indications.
This LPG Gas Sensor (MQ6), ideal sensor for use to detect the presence of a dangerous
Liquefied petroleum gas (LPG) and it has high sensitivity to propane, butane, isobutene, natural
gas. The sensor can also be used to detect combustible gases, especially methane. This circuit can
detect leakages in your Home, car or in a service station, storage tank environment. This unit can
be easily implemented to industrial level by upgrading its ranges.
This project is designed to detect the LPG from 200parts per million (PPM) to 10,000 PPM.
Whenever there is LPG concentration of 1000 ppm (parts per million) in the area, the OUT pin of the
sensor module goes high. This LPG Gas Sensor can be used to make wireless Gas leak detector in
home security system .The LPG Gas Sensor Module is designed to enable LPG detection interface to
AVR-controller without inbuilt ADC Channels. By providing a GSM modem we can receive “SMS
ALERTS” also..
CONTROLLER-AVR-AT-MEGA328
FEATURES
The AVR-ATMEGA328, CMOS FLASH-based 8-bit microcontroller is upward compatible with
theATmega48A
,ATmega48PA
,ATmega88A
,ATmega88PA
,ATmega168A
,ATmega168PA
,ATmega328 ,ATmega328P devices. It features 200 ns instruction execution, 256 bytes of EEPROM
data memory, self programming, an ICD, 2 Comparators, 8 channels of 8 bit Analog-to-Digital (A/D)
converter, 2 capture/compare/PWM functions, a synchronous serial port that can be configured as
either 3-wire SPI or 2-wire I2C bus, a USART, and a Parallel Slave Port.
High Performance RISC CPU
 Only 35 single word instructions to learn
 All single cycle instructions except for program branches which are two-cycle
 Operating speed: DC 20 MHz clock input, DC 200 ns instruction cycle
 Up to 8K x 14 words of FLASH Program Memory

Up to 368 x 8 bytes of Data Memory (RAM)
 Pin out compatible to the ATmega48A,ATmega48PA,ATmega88A,
 Pin out compatible to the ATmega88PA,ATmega168A,ATmega168PA
 Interrupt capability (up to 12 sources)
 Eight level deep hardware stack
 Direct, Indirect and Relative Addressing modes

Processor read access to program memory
Special Microcontroller Features
 Power up Timer (PWRT) and oscillator Start up Timer (OST)
 Watchdog Timer (WDT) with its own on chip RCoscillator for reliable operation
 Programmable code protection
 Power saving SLEEP mode
 Selectable oscillator options
 In Circuit Serial Programmingvia twoPins
Peripheral Features
 Timer0: 8-bit timer/counter with 8-bit prescaler

Timer1: 16-bit timer/counter with prescaler can be incremented during Sleep via external
crystal/clock

Timer2: 8-bit timer/counter with 8-bit period register, prescaler and postscaler

Two Capture, Compare, PWM modules

16-bit Capture input; max resolution 12.5 ns

16-bit Compare; max resolution 200 ns

PWM max resolution is 10-bit

Synchronous Serial Port (SSP) with SPI (Master mode) and I2C (Slave)

8-bit, up to 8-channel Analog-to-Digital converter


Universal Synchronous Asynchronous Receiver Transmitter (USART/SCI)
Parallel Slave Port (PSP), 8-bits wide with external RD, WR and CS controls (28/44-pin
Only)

Brown-out detection circuitry for Brown-Out Reset
Analog Comparator module
 2 analog comparators
 Programmable on-chip voltage reference module
 Programmable input multiplexing from device inputs and internal VREF
 Comparator outputs are externally accessible
CMOS Technology
 Low power, high speed CMOS FLASH technology

Fully static design
 Wide operating voltage range: 2.0V to 5.5V

High Sink/Source Current: 25 mA

Industrial temperature range

Low power consumption

< 2 mA typical @ 5V, 4 MHz,

A typical @ 3V, 32 kHz

< 1 μA typical standby current
Following are the major blocks of AVR Microcontroller.
Program Memory (FLASH)
It is used for storing a written program. Since memory made in FLASH technology can be
programmed and cleared more than once, it makes this microcontroller suitable for device
development.
EEPROM
It is usually used for storing important data that must not be lost if power supply suddenly stops.
For instance, one such data is an assigned temperature in temperature regulators. If during a loss
of power supply this data was lost, we would have to make the adjustment once again upon return
of supply. Thus our device looses on self-reliance.
RAM
Data memory used by a program during its execution. In RAM are stored all inter-results or
temporary data during run-time.
FREE RUN TIMER
It is an 8-bit register inside a microcontroller that works independently of the program. On every
fourth clock of the oscillator it increments its value until it reaches the maximum (255), and then it
starts counting over again from zero. As we know the exact timing between each two increments of
the timer contents, timer can be used for measuring time which is very useful with some devices.
LCD DISPLAY
DISPLAY: Various display device such as seven segment display. LCD display, etc can be interfaced
with microcontroller to read the output directly. In our project we use a two line LCD display with 16
characters each. LCD Liquid crystal Display (LCD) displays temperature of the measured element,
which is calculated by the microcontroller. CMOS technology makes the device ideal for application
in hand held, portable and other battery instruction with low power consumption.
GENERAL SPECIFICATION:









Drive method: 1/16 duty cycle
Display size: 16 character * 2 lines
Character structure: 5*8 dots.
Display data RAM: 80 characters (80*8 bits)
Character generate ROM: 192 characters
Character generate RAM: 8 characters (64*8 bits)
Both display data and character generator RAMs can be read from MPU.
Internal automatic reset circuit at power ON.
Built in oscillator circuit.
Net Media 2x16 Serial LCD Display Module
POWER SUPPLY
There are many types of power supply. Most are designed to convert high voltage AC mains
electricity to a suitable low voltage supply for electronic circuits and other devices. A power supply
can by broken down into a series of blocks, each of which performs a particular function.
For example a 5V regulated supply:
Each of the blocks is described in more detail below:
 Transformer - steps down high voltage AC mains to low voltage AC.
 Rectifier - converts AC to DC, but the DC output is varying.
 Smoothing - smoothes the DC from varying greatly to a small ripple.
 Regulator - eliminates ripple by setting DC output to a fixed voltage.
Power supplies made from these blocks are described below with a circuit diagram and a
graph of their output:




Transformer
Transformer
Transformer
Transformer
only
+ Rectifier
+ Rectifier + Smoothing
+ Rectifier + Smoothing + Regulator

Transformer only
The low voltage AC output is suitable for lamps, heaters and special AC motors. It is not suitable
for electronic circuits unless they include a rectifier and a smoothing capacitor.

Transformer + Rectifier
The varying DC output is suitable for lamps, heaters and standard motors. It is not suitable for
electronic circuits unless they include a smoothing capacitor.

Transformer + Rectifier + Smoothing
The smooth DC output has a small ripple. It is suitable for most electronic circuits. Transformer +
Rectifier + Smoothing + Regulator
# The regulated DC output is very smooth with no ripple. It is suitable for all electronic circuits. The
fig. above shows the circuit diagram of the power supply unit. This block mainly consists of a two
regulating IC 7805 and a bridge rectified and it provides a regulated supply approximately 5V.The
transformer used in this circuit has secondary rating of 7.5V. The main function of the transformer
is to step down the AC voltage available from the main. The main connections are given to its
primary winding through a switch connected to a phase line. The transformer provides a 7.5V AC
output at its secondary terminals and the maximum current that can be drawn form the transformer
is 1 Amp which is well above the required level for the circuit.The bridge rectified the AC voltage
available from the secondary of the transformer, i.e. the bridge rectifier convert the AC power
available into DC power but this DC voltage available is not constant. It is a unidirectional voltage
with varying amplitude.
#To regulate the voltage from the bridge rectifier, capacitors are connected. Capacitors C1 filter the
output voltage of the rectifier but their output is not regulated and hence 7805 is connected which is
specially designed for this purpose.Although voltage regulators can be designed using op-amps, it is
quicker and easier to use IC voltage regulator. Further more, IC voltage regulators are available
with features such as programmable output current/ voltage boosting, internal short circuit current
limiting, thermal shut down and floating operation for high voltage applications.
The 78 XX series consists of three terminals viz, input, output & ground. This is a group of fixed
positive voltage regulator to give and output voltage ranging form 5V to 24V.
These IC’s are
designed as fixed voltage regulators and with adequate heat sinking, can delivery output current in
excess of 1 Amp although these devices do not require external components and such components
can be used to obtain adjustable voltage and current limiting. In addition, the difference between
the input and output voltages (V in Vo) called the dropout voltage must be typically 2V even from a
power supply filter.
#Capacitors C2, C3, C4, and C5 are small filters which are used for extra filtering.LED1& LED2 are
used for Power ON indicator for IC1 and IC2, current-limiting resistors R2&R4, which prevents the
LED’s from getting heated and thus damaged.
What is a GSM Modem?
A GSM modem is a specialized type of modem which accepts a SIM card, and operates over a
subscription to a mobile operator, just like a mobile phone. From the mobile operator perspective, a
GSM modem looks just like a mobile phone.
When a GSM modem is connected to a computer, this allows the computer to use the GSM modem
to communicate over the mobile network. While these GSM modems are most frequently used to
provide mobile internet connectivity, many of them can also be used for sending and receiving SMS
and MMS messages.
A GSM modem can be a dedicated modem device with a serial, USB or Bluetooth connection, or it
can be a mobile phone that provides GSM modem capabilities.
For the purpose of this document, the term GSM modem is used as a generic term to refer to any
modem that supports one or more of the protocols in the GSM evolutionary family, including the
2.5G technologies GPRS and EDGE, as well as the 3G technologies WCDMA, UMTS, HSDPA and
HSUPA.
TECHNICAL DETAILS
GSM is a cellular network, which means that mobile phones connect to it by searching for cells in
the immediate vicinity. There are five different cell sizes in a GSM network—macro, micro, Pico,
femto and umbrella cells. The coverage area of each cell varies according to the implementation
environment. Macro cells can be regarded as cells where the base station antenna is installed on a
mast or a building above average roof top level. Micro cells are cells whose antenna height is under
average roof top level; they are typically used in urban areas. Pico cells are small cells whose
coverage diameter is a few dozen meters; they are mainly used indoors. Femto cells are cells
designed for use in residential or small business environments and connect to the service provider’s
network via a broadband internet connection. Umbrella cells are used to cover shadowed regions of
smaller cells and fill in gaps in coverage between those cells.
GSM CARRIER FREQUENCIES
GSM networks operate in a number of different carrier frequency ranges (separated into GSM
frequency ranges for 2G and UMTS frequency bands for 3G), with most 2G GSM networks operating
in the 900 MHz or 1800 MHz bands. Where these bands were already allocated, the 850 MHz and
1900 MHz bands were used instead (for example in Canada and the United States). In rare cases
the 400 and 450 MHz frequency bands are assigned in some countries because they were previously
used for first-generation systems.
Most 3G networks in Europe operate in the 2100 MHz frequency band. Regardless of the frequency
selected by an operator, it is divided into timeslots for individual phones to use. This allows eight
full-rate or sixteen half-rate speech channels per radio frequency. These eight radio timeslots (or
eight burst periods) are grouped into a TDMA frame. Half rate channels use alternate frames in the
same timeslot. The channel data rate for all 8 channels is 270.833 Kbit/s, and the frame duration is
4.615 ms.
The transmission power in the handset is limited to a maximum of 2 watts in
GSM850/900 and 1 watt in GSM1800/1900.
NETWORK STRUCTURE
The structure of a GSM network
The network is structured into a number of discrete sections:

The Base Station Subsystem (the base stations and their controllers).

the Network and Switching Subsystem (the part of the network most similar to a fixed network).
This is sometimes also just called the core network.

The GPRS Core Network (the optional part which allows packet based Internet connections).

The Operations support system (OSS) for maintenance of the network.
SUBSCRIBER IDENTITY MODULE
One of the key features of GSM is the Subscriber Identity Module, commonly known as a SIM card.
The SIM is a detachable smart card containing the user's subscription information and phone book.
This allows the user to retain his or her information after switching handsets. Alternatively, the user
can also change operators while retaining the handset simply by changing the SIM. Some operators
will block this by allowing the phone to use only a single SIM, or only a SIM issued by them; this
practice is known as SIM locking.
Project Members
#Nikhil Patil
#Gaurav Patil
#Pritesh Patil
G.H.RAISONI COLLEGE OF ENGINEERING AND MANAGEMENT, JALGAON