School Papers

A GSM to facilitate the communication of displaying

                 A GSM based digital notice board
and  a 
home automation  system has a    very low cost of installation and
maintenance. GSM SIM900 is the most popular standard for mobiles in the world.
It
presents an SMS based notice board incorporating the widely used GSM to
facilitate the communication of displaying message on notice board via user’s
mobile phone. When the user sends a SMS via a registered number from his mobile
phone, it is received by SIM300 GSM modem at the receiver’s end. If the user
wants to display any message, he can send the information by SMS and thus
update the LCD display accordingly. The   system consists
of a 32-bit ARM   based   microcontroller   LPC2148,  
GSM SIM900 module,   an LCD, a
motor   and   an android  
application   for   user  
interface    with   the  
hardware.

Keywords:

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1. Introduction

               Every system is automated in
order to face new challenges in the present day situation. Automated systems
have less manual operations, so that the flexibility, reliabilities are high
and accurate. Hence every field prefers automated control systems. Especially
in the field of electronics automated systems are doing better performance
increasingly. Probably the most
useful thing to know about the global system for mobile communication is that
it is an international standard. If you travel in parts of world, GSM is only
type of cellular service available. Instead of analog services, GSM was
developed as a digital system using TDMA technology. The main aim of this paper is to module GSM based wireless smart
home and digital notice board for the development of a system, which uses
Mobile technology that keeps monitoring of the various appliances, and will
control the operation of these appliances with respect to the signal sent by
the mobile. For utilization of appliances the new concept has been thought to
manage them remotely by using GSM, which enables the user to remotely control
switching of domestic appliances. Just by dialing keypad of remote telephone,
from where you are calling you can perform ON / OFF operation of the
appliances.

 

 

2. METHODOLOGY

            In this paper we are monitoring and
controlling appliances of home remotely using GSM technology. The required
operating voltage for Microcontroller 89C51 is 5V. Hence the 5V D.C. power
supply is needed by the same. This regulated 5V is generated by stepping down
the voltage from 230V to 12V using step down transformer. Now the step downed
a.c voltage is being rectified by the Bridge Rectifier using 1N4007 diodes. The
rectified a.c voltage is now filtered using a ‘C’ filter. Now the rectified,
filtered D.C. voltage is fed to the Voltage Regulator. This
voltage regulator provides/allows us to have a Regulated constant Voltage which
is of +5V. The rectified filtered and regulated voltage is again filtered for
ripples using an electrolytic capacitor 100?F. Now the output from this section
is fed to 40th pin of 89c51 microcontroller to supply operating
voltage.   The microcontroller 89C51 with Pull up resistors
at Port0 and crystal oscillator of 11.0592 MHz crystal in conjunction with
couple of 30-33pf capacitors  is placed
at 18th & 19th pins of 89c51 to make it work
(execute) properly. Operating voltage for the GSM modem will depends on its
type and an adaptor is provided with the GSM modem set itself. Now to monitor
and control the appliances of home, just we need to send a SMS from remote
telephone to the GSM modem which is present in home. Modem will read this SMS
and forwards to the microcontroller. Now the controller will process this data
and depending upon the message sent it will perform the action. Such that to
operate the lamps in the home controller will gives signals to the
corresponding relays to perform that action and to operate the DC Fan or DC
motor signal is to its respective drivers.

          Like this all the appliances in home can be
controlled by using this GSM technology. If we want to know the status of
appliances in home just a SMS is sent through the GSM modem via network paths
using AT commands to our mobiles which includes the status of the appliances.

3. GSM BASED SMART HOME AND DIGITAL
NOTICE BOARD

The
main aim of this paper GSM based wireless smart home and digital notice board is
to develop a system, which uses Mobile technology that keeps monitoring of the
various appliances, and will control the operation of these appliances with
respect to the signal sent by the mobile. For utilization of appliances the new
concept has been thought to manage them remotely by using GSM, which enables
the user to remotely control switching of domestic appliances. Just by dialing
keypad of remote telephone, from where you are calling you can perform ON / OFF
operation of the appliances. The block diagram of the proposed approach is
shown in Figure 1 and it consists of Microcontroller, MAX 232, GSM, LCD
display, power supply, relay, driver, fan and bulbs.

Micro-controllers
were originally used as components in complicated process-control systems.   However, because of their small size and low
price, Micro-controllers are now also being used in regulators for individual
control loops. In several areas Micro-controllers are now outperforming their
analog counterparts and are cheaper as well. To allow compatibility
among data communication equipment made by various manufactures, an interfacing
standard called RS232 was set by the Electronic Industries Association
(EIA).This RS-232 standard is used in PCs and numerous types of equipment. However,
since the standard was set long before the advent of the TTL logic family, its
input and output voltage levels are not TTL compatible. In RS-232 ,a 1 is
represented by  -3 to -25V,while a 0 bit
is +3 to +25V,making -3 to +3 undefined. For this reason, to connect any RS-232
to a microcontroller system we must use voltage converters such as MAX232 to
convert the TTL logic levels to the RS-232 voltage levels and vice versa. So
here we are using this MAX-232 to have compatibility between the RFID READER
and microcontroller.

            GSM based wireless home appliances monitoring and
control using GSM, which enables the user to remotely control switching of
domestic appliances. Just by dialing keypad of remote telephone, from where you
are calling you can perform ON / OFF operation of the home appliances.  A variable regulated
power supply, also called a variable bench power supply, is one where you can
continuously adjust the output voltage to your requirements. Varying the output
of the power supply is the recommended way to test a project after having
double checked parts placement against circuit drawings and the parts placement
guide. This type of regulation is ideal for having a simple variable bench
power supply. Actually this is quite important because one of the first
projects a hobbyist should undertake is the construction of a variable
regulated power supply. While a dedicated supply is quite handy e.g. 5V or 12V,
it’s much handier to have a variable supply on hand, especially for testing.
Most digital logic circuits and processors need a 5 volt power supply. To use
these parts we need to build a regulated 5 volt source. Usually you start with
an unregulated power supply ranging from 9 volts to 24 volts DC (A 12 volt
power supply is included with the Beginner Kit and the Microcontroller Beginner
Kit.). To make a 5 volt power supply, we use a
LM7805 voltage regulator IC.

The LM7805 is
simple to use. You simply connect the positive lead of your unregulated DC
power supply (anything from 9VDC to 24VDC) to the Input pin, connect the
negative lead to the Common pin and then when you turn on the power, you get a
5 volt supply from the Output pin. LCD is used to display the information about
the current process. A relay is an electrical switch that opens and closes
under control of another electrical circuit. In the original form, the switch
is operated by an electromagnet to open or close one or many sets of contacts.
The schematic representation of GSM based smart home are shown in Figure 2.

Firstly, the required operating voltage for
Microcontroller AT89S52 is 5V. Hence the 5V D.C. power supply is needed by the
same. This regulated 5V is generated by first stepping down the 230V to 18V by
the step down transformer. In the both the Power supplies the step downed a.c.
voltage is being rectified by the Bridge Rectifier. The diodes used are 1N4007.
The rectified a.c voltage is now filtered using a ‘C’ filter. Now the
rectified, filtered D.C. voltage is fed to the Voltage Regulator. This voltage
regulator allows us to have a Regulated Voltage. In Power supply given to
Microcontroller 5V is generated using 7805 and in other two power supply 12V is
generated using 7812. The rectified; filtered and regulated voltage is again
filtered for ripples using an electrolytic capacitor 100?F. Now the output from
the first section is fed to 40th pin of AT89S52 microcontroller to
supply operating voltage and from other power supply to circuitry. The
microcontroller AT89S52 with Pull up resistors at Port0 and crystal oscillator
of 11.0592 MHz crystal in conjunction with couple of capacitors of  is placed at 18th & 19th
pins of AT89S52 to make it work (execute) properly.P0 is connected to the data pins of the LCD.         P2.5, P2.6, P2.7 are connected to
control pins of the LCD.20th is connected to GROUND and 40th is connected to Vcc. The
architecture of GSM network is shown in Figure 3.

relay is an electrically operated switch. Current
flowing through the coil of the relay creates a magnetic field which attracts a
lever and changes the switch contacts. The coil current can be on or off so
relays have two switch positions and they are double throw (changeover)
switches and the figure is shown in Figure 4.

Relays allow one circuit to switch
a second circuit which can be completely separate from the first. For example a
low voltage battery circuit can use a relay to switch a 230V AC mains circuit.
There is no electrical connection inside the relay between the two circuits,
the link is magnetic and mechanical. The coil of a relay passes a relatively
large current, typically 30mA for a 12V relay, but it can be as much as 100mA
for relays designed to operate from lower voltages. Most ICs (chips) cannot
provide this current and a transistor is usually used to amplify the small IC current to the
larger value required for the relay coil. The maximum output current for the
popular 555 timer IC is 200mA so these devices can supply relay coils directly
without amplification. The relay’s switch connections are usually labeled COM,
NC and NO:

·        
COM = Common, always connect to this, it is the moving part of the
switch.

·        
NC = Normally Closed, COM is connected to this when the relay coil
is off.

·        
NO = Normally Open, COM is connected to this when the relay coil is on.

Connect to COM and NO if you want
the switched circuit to be on when
the relay coil is on.
Connect to COM and NC if you want
the switched circuit to be on when
the relay coil is off.

The flowchart
of GSM based smart Notice Board  is shown
in Figure 5.

.  IMPLEMENTATION

            The microcontroller receives an SMS through the GSM
module on occurrence of one of the two events: (a) when a notice is sent by a
user through application; (b) user clicks on ON/OFF button in the application. When the SIM inserted in the GSM
module receives a notice as an SMS from a user, it saves the SMS and the data
is transferred to LPC2148 through DB9 port of GSM to usb port of ARM
development board connected by USB to RS232 driver.  On receiving data from the GSM, LPC2148 sends
a write command to the 16*2 alphanumeric LCD followed by transfer of data to
the 8 data pins of the LCD.  The
application named Home Automation is used to send message that gets displayed
in the LCD.  On clicking an ON/OFF
button, an SMS is generated and sent by the application Home Automation to the
SIM in GSM module.  The GSM module
transfers the data to LPC2148 as explained. On receiving the data, LPC2148
sends a signal (logic 0 or logic 1) to the relay driver which turns the motors
on/off as per the message. Microcontroller
LPC2148 and the GSM SIM900 module communicate through any one of the two UART
devices which are 16C550 present in the LPC2148 chip. In this project, UART0
has been used to connect to the GSM module. Among all the 64 pins of the
microcontroller, pin P0.0 is the TXD0 (transmit) pin and pin P0.1 is the RXD0
(receive) pin. The RXD0 and TXD0 pins of LPC2148 are connected to the Tx and Rx
of the GSM Module respectively with jumper wires. The UART is initialized for
communication to happen. The Frequency Of Crystal Oscillator (FOSC) is 12MHz
and to maintain a frequency of 60MHz for the CPU (Fcclk) through Phase Locked Loop
(PLL) output, the multiplier is set as M=5 and the following registers are
configured: PLL0CON=0x01 PLL0CFG=0x24 The sequence fed is: PLL0FEED=0Xaa
PLL0FEED=0x55. Hence, the peripheral
clock frequency Fpclk is set as Fcclk/4. The baud rate generated is 9600 bauds
per second using the formula, baud rate B, 
Fpclk in Hz

B=16(256(DLM) + DLL)(1
+ D=M)            (1)

 Where registers U0DLL = 97 ;  U0DLM = 1 ; MULVAL = 15 ; DIVADDVAL = 0

Here, in formula, DLL
stands for U0DLL, DLM stands for U0DLM, M for MULVAL and D for DIVADDVAL. On
setting the baud rate at 9600 bps, the UART gets ready to communicate with the
GSM module. To communicate with GSM, Attention (AT) commands are sent to GSM module
through UART of LCP2148. So, initially to ensure successful connection with GSM
module, the data  “AT” is sent through
UART. If in return  “OK” is received by
UART from GSM, then the connection is successful else not. After ensuring
connection established, the GSM modem is set to text mode to read the SMS in
text mode otherwise it gets displayed in binary mode. So, the string
“AT+CMGF=1” is send to GSM module which sets the SMS at index 1 in text mode.
Since, it is known that the latest SMS is always stored at index 1, the data
sent is “AT+CMGF=1” where 1 is the index number of the message. Next, in order
to read the message and send it for display the string “AT+CMGR=1” is sent to
GSM. This string is sent to read the message at index number 1 as it is the
latest SMS received by the SIM in GSM. Finally, after the message is read, it
is sent to LCD in 4-bit mode and displayed. 

            The
16*2 LCD has eight data pins and three special pins namely, Read/Write (R/W), Enable
(E) and Register Select(RS). It can be used in 4-bit or 8-bit mode to transfer
data or command. In 8-bit mode, all the eight data lines of LCD are connected
to eight I/O pins of LPC2148 along with three other pins also connected to the
microcontroller but in 4-bit mode, only four data lines are connected to the
microcontroller. Here, 4-bit mode has been used to display

            In 4-bit mode, the data lines D0-D3
of LCD are not connected and D4-D7 are connected to pins P0.19P0.22 of LPC2148.
The R/W, E and RS pins are connected to pins P0.16, P0.17 and P0.18 pins of
LPC2148 respectively. Initially, the LCD is initialized and then the data is
sent to it to get it displayed. RS pin, if high, selects the data register and
LCD interprets any data sent to it as data to be displayed and if RS pin is
low, command register is selected so the data sent to LCD is interpreted as a
command by the LCD. The enable pin is used to enable transfer of command or
data to LCD from microcontroller. The command/data transfer is enabled when E
pin gets a transition from high to low. The R/W pin, if high gives read
operation and gives write operation otherwise.

            For initialization, the pins R/W is
kept low (write), RS is kept low (command register selected) and then command
is sent through the 4-bit mode. But to place the command into command register,
E pin is transitioned from high to low each time a byte is sent to the LCD. The
commands sent for initialization in hexadecimal are, 28H, 20H, 06H, 01H and 80H.The
application includes Home appliance control, Industrial applications, Hotel
lights / fans control Shops  and
showrooms.

                                                    

                                                   
CONCLUSION

 

The paper GSM
based smart home and digital notice board  has been successfully designed and tested.It has been
developed by integrating features of all the hardware components used. Presence
of every module has been reasoned out and placed carefully thus contributing to
the best working of the unit. Secondly, using highly advanced IC’s and with the
help of growing technology the notice board based on digital has been
successfully implemented. It can reduce use of papers and hence deforestation can be turned into Afforestation.
It can reduce physical effort of printing and distribute- It is cheap, quick,
reliable and secured for any organizing paper based notices. it requires to
circulate notices regularly and reduces physical effort as well as ensures
energy consumption management for any user. Although only fan has been driven
through the system, in future, other devices like microwave, washing machine
can also be operated while the user is aged or not at home.

REFERENCES

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2
H. Elkamchouchi and A. ElShafee, “Design and prototype implementation of sms
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(ICEDSA), 2012 IEEE International Conference on, Nov 2012, pp. 162–167. 

 3 B. Ghazal, M. Kherfan, K. Chahine, and K.
Elkhatib, “Multi control chandelier operations using xbee for home automation,”
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4
G. Cao, T. Xu, T. Liu, Y. Ye, and G. Xu, “A gsm-based wireless remote
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5
D.-M. Han and J.-H. Lim, “Smart home energy management system using ieee
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6
M. S. Khandare and A. Mahajan, “Mobile monitoring system for smart home,” in
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