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Автор: Sarinee Ouitrakul
2014 3rd International Conference on Informatics, Environment, Energy and Applications
IPCBEE vol.66 (2014) © (2014) IACSIT Press, Singapore
DOI: 10.7763/IPCBEE. 2014. V66. 18
Wireless Load Control Device using GSM Module
Sarinee Ouitrakul and Sirichai Watanasophon
Department of Electrical Engineering
Faculty of Engineering at Si Racha, Kasetsart University Si Racha Campus
Chonburi, Thailand
Abstract. This paper presents Wireless Load Control Device (WLCD) using GSM module. The WLCD
consists of PIC18F4550, GSM Module, relay circuit, keypad, and LCD. PIC18F4550 is used as a
microcontroller to process the received data and then the output signal is sent for on/off relay switch. The
users can on/off load in two ways, either keypad or short message service (SMS). The WLCD can control
three loads and the current status of each load is displayed on the LCD. A working prototype of WLCD was
built to demonstrate the effectiveness and efficiency of on/off load control through the GSM network.
Keywords: wireless load control device, PIC microcontroller, 18F4550, GSM module, SIM900B
1. Introduction
Nowadays, the innovative technologies have become an integral part of human life. Various load control
method and technology such as power line carrier (PLC), telephone modem, internet, WIFI, Bluetooth, and
ZigBee were established and developed to facilitate comfortable for humans. There are many researches
about load control method and technology until now. For example, in 2000, R. C. Luo et al. [1] presented
intelligent autonomous mobile robot control through the Internet. In 2010, X. Liu and W. Wang [2]
introduced a control system of indoor intelligent Lighting which is based on power line carrier
communication. The power line is used to transmit the analogue or digital signals with high speed. Not only
power line technology but also wireless remote control and GSM network are used to combine for remote the
indoor intelligent lighting and controlling the sensing. Architecture for power monitoring system using the
wireless sensor network technology is proposed in 2011 [3]. In 2013, V. Bhatia and P. Whig [4] presents the
modelling and simulation of electrical load control system using RF technology. Moreover, V. Bhatia and P.
Whig [5] designed and simulated the smart elevator control system with Security based on Dual Tone Multi
Frequency. R. Makwana et al. [6] tried to study the comparative of different wireless protocol between
ZigBee (over IEEE 802.15.4) and Bluetooth (over IEEE 802.15.1).
In addition, the microcontrollers are playing a very important role in the development of the smart
systems [2-5]. The microcontroller is basically a single chip microprocessor suited for machine controlling
and system processing because it carries out autonomous operations and takes smart decisions. Moreover,
the devices such as air conditioners, power tools, toys, office machines employ microcontrollers for its
operation.
This paper designs and develops the control of electrical loads using GSM module. PIC18F4550 is used
for processing and controlling of the WLCD. By pressing the keypad on the WLCD, the controllability of the
electrical load can be achieved. Moreover, the users can send the command to remote control the electrical
load and receive the current status of the load by GSM module.
2. Material and Method
Corresponding author. Tel.: +66 (0)38 354849-52 ext. 2818; fax: + 66 (0)38 354849.
E-mail address: sarinee@eng.src.ku.ac.th.
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The complete system of WLCD can be shown in Fig. 1, consists of four major parts: (1) input command,
(2) microcontroller, (3) output display, and (4) electrical load driver.
Output display
Input command
keypad
LCD
Mobile
Microcontroller
Phone
Electrical load driver
Microcontroller
GSM module
Relay Driver
Electrical Load
Fig. 1: Block diagram of the WLCD
2.1.1. Hardware Implement
2.1.2. Input Command
WLCD can receive the input command in two ways (i.e. keypad or SMS). 3x4 keypad switches are
connected to the microcontroller for sending the input command to control each electrical load. In the other
way, the user can interface with the WLCD by sending the SMS from the mobile phone to its. The GSM
module (SIM900B) is used to receive that SMS from the user via GSM network and send the data to the
microcontroller via RS232 serial port.
2.1.3. Microcontroller
A microcontroller (PIC18F4550) is used as an interface device (input command, LCD and the electrical
load driver). It is a 40-pin dip, low power consumption and high speed FLASH/EEPROM technology. It
consists of 256 bytes EEPROM memory, 35 Input/output, two external clock modes (up to 48MHz), 13
channels of
10-bit analog to digital converter, and a capture/compare/PWM functions. 7805 voltage
regulators are used to convert 12Vdc to 5Vdc and the output is then given to the microcontroller and GSM
module. The electrical load driver, keypad and LCD are connected with microcontroller at port A, B and D,
respectively.
2.1.4. Output of the WLCD
16X2 LCD is used in the system to display the current status of the WLCD. Besides the LCD, the user
can receive the current status of electrical load by sending SMS to the WLCD.
2.1.5. Electrical load driver
The electrical load driver includes the opto-isolator and the relay circuit. The opto-isolator has the
function to transmit the output signal from the microcontroller to the relay circuit. The relay circuit is an
interrupting device designed for shutting on/off the power supply. The relay switch is designed for the
electrical load at 220Vac and 10A. When the WLCD receives the command, the microcontroller will control
the relay switch to on/off the electric power supply via the opto-isolator. The prototype of hardware
implementation was done as shown in Fig.2.
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Fig. 2: the WLCD prototype
2.1.6. Software Implement
According to the hardware circuit design features, WLCD controlling program flowchart is introduced as
shown in Fig. 3. First, the system initializes each module, and then turns off all electrical loads. Then,
WLCD started already, the microcontroller sends the command of AT + CMGD = 2 for clearing the second
data storage space in the SIM card of GSM module. When the user sends the short messages to WLCD,
GSM module will send that command to the microcontroller. After that the microcontroller will turn on/off
load according to the received command and show the current status on the LCD. The microcontroller sends
a command (such as AT+CMGS="+66868273639" and “SW1-ON SW2-ON SW3-OFF”) to the GSM
module for informing the current status to the user. In the other way, when the received command is sent
from the keypad, the WLCD will operate to on/off the electrical load and show the current status of each
electrical load on the LCD module.
Start
Device
initialization
keypad
Is cmd Rx from
SMS
Set
Relay switch
Set Relay switch
Send cmd to
inform the current
status via SMS
Show current
status on LCD
Fig. 3: Flow diagram of WLCD controlling program
Table 1 shows the control command to control the electrical loads of WLCD. For example, when the
user need to on only SW2, the command is “*010#”.
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Table 1: WLCD control commands
Command
SW1
SW2
SW3
*000#
OFF
OFF
OFF
*001#
OFF
OFF
ON
*010#
OFF
ON
OFF
*011#
OFF
ON
ON
*100#
ON
OFF
OFF
*101#
ON
OFF
ON
*110#
ON
ON
OFF
*111#
ON
ON
ON
3. Results
Electrical loads such as fans, bulbs, and computer etc. are tested and controlled wirelessly by the WLCD.
When starting up the program, the LCD will show as Fig. 4(a). Then, three electrical loads can be controlled
at a time in the present system. For example, when the user enters “*000#” to the WLCD using keypad, all
of electrical loads will turn off and the LCD will show the current status as shown in Fig. 4 (b). Next, the
user sends the SMS command (“*111#”) to the WLCD, the LCD will show the phone number of a user as
shown in Fig. 4 (c). Then, all loads are switched on and the LCD will show the current status of electrical
load as shown in Fig. 4 (d). After that, the microcontroller will send the current status to the user via SMS as
shown in Fig. 4 (e).
(a) Start up the program
(c) the number of user who send the command to the WLCD
(b) Off all electrical load
(d) On all electrical load
(e) SMS send and receive from WLCD
Fig. 4: the result of WLCD
4. Conclusion
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To control the electrical load by wireless communication using GSM module, the WLCD was
constructed. The WLCD is designed to provide three loads (rated of each load at 220Vac 10A). The
electrical loads can be turned on/off by keypad on WLCD or SMS via GSM network as the command shown
in Table 1. The user can know the current load status by LCD on WLCD or the SMS from WLCD.
The advantage of WLCD can be stated as follows:
- wireless control from remote places,
- ease of operation by using any mobile possible to on/off electrical load,
- the users will get a convenient, and
- time saving.
In addition, this WLCD can be applied to the other systems such as controlling the pump, motor, etc. In
the future work, we will add the electrical measuring system which can read and send the electrical
measuring value such as power and energy to the user. The system will be designed to increase the current
load more than 10A by using the higher size of the relay. Moreover, the WLCD can be extended to the
desired number of loads by adding the relay circuits and changing the control commands.
5. References
[1] R.C. Luo, T.M. Chen, and C.C. Yih. Intelligent Autonomous Mobile Robot Control through the Internet. IEEE
International Symposium ISIE. 2000, 1: 6-11.
[2] X. Liu and W. Wang. Indoor Intelligent Lighting Control System Based on Power Line Carrier Design. 2010
Second WRI Global Congress on Intelligent Systems (GCIS), 2010, 1: 408-411.
[3] R. V. P. Yerra et al. WSN based power monitoring in smart grids. Seventh International Conference on Intelligent
Sensors, Sensor Networks and Information Processing (ISSNIP), 2011, 401-406.
[4] V. Bhatia and P. Whig. Modelling and Simulation of Electrical Load Control System using RF Technology.
International Journal of Multidisciplinary Science and Engineering, 2013, 4(9): 44-47.
[5] V. Bhatia and P. Whig. A Secured Dual Tone Multi Frequency based Smart Elevator Control System.
International Journal of Research in Engineering & Advanced Technology. 2013, 1(4): 1-5.
[6] R. Makwana et al. Wireless Based Load Control and Power Monitoring System. International Conference on
Energy Efficient Technologies for Sustainability (ICEETS), 2013, 1207 - 1211.
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