MODERN HOME AUTOMATION SYSTEM FORENERGY CONSERVATION

Archis Bnaerjeea,1, Sadeque Reza Khanb,2,∗, M.S.Bhatb,3

aDept. of EEE, National Institute of Technology Karnataka,Surathkal.bDept. of ECE, National Institute of Technology Karnataka,Surathkal.

Abstract

Last decade has seen serious concerns for the future availability of electricalenergy due to the drastic depletion of the conventional fuel resources. Varioussolutions have been proposed and implemented, of which, using the availableenergy in the most efficient manner has been seen to give great results in energyconservation. This project contributes to the efforts of energy conservation withthe help of cost effective embedded automation. The system offers two modes,one automatic, and the other manual. The former automates the electrical sys-tems of the home to a large extent using the outputs of various sensors througha control mechanism using PIC microcontroller 16F877A, keeping the energyconservation as its primary concern, while the latter is a more of a conven-tional system, giving the user certain new perks of the existing technology likecontrolling the electrical appliances, fans and lighting systems through InfraredRemote Control. The system is accompanied with the technology of The GlobalSystem for Mobile communication (GSM).

Keywords: LDR; PIR Sensor;LM35DZ; IR Tansmitter-Receiver; RS232.

1. Introduction

In today’s world, it is very important to have sufficient energy for the contin-uous growth of the human society in varied fields[1].But as evident from the factsand figures, the gap between the supply and demand of electricity is increasingeach year. India, for example, even after being the fifth largest electrical en-ergy producer, still suffered from 7 percent average power shortage in the year2007-2008, and the trend is continuing the same way [2]. Also, the conventionalnon- renewable resources, which are the major contributors to the present dayenergy, are forecasted not to last very long.

∗Corresponding author1B.Tech, Dept. of EEE, National Institute of Technology Karnataka,Surathkal.2M.Tech(VLSI), Dept. of ECE, National Institute of Technology Karnataka,Surathkal.3Honorary Professor, National Institute of Technology Karnataka,Surathkal.

Preprint submitted to ICC-2014 April 8, 2014

Now, automation is one of the finest implementations of the technologicaldevelopments. Automation basically is meant to avoid the necessity of address-ing the same problem again, once it had been solved earlier. For example, ina plastic bottle factory, once the design for the dye is made, the same dye canbe used to produce thousands of bottles of the exact dimensions, with so muchlesser man power. Today’s industries, and hence the growth of the whole so-ciety, is revolutionized by automation. Automation, when applied to domesticenvironment, brings better convenience, better security, a flexible and a morecomfortable life [3], [4]. This paper brings out two aspects of home automation,which are user convenience and energy conservation. For the chief objectives ofthe home automation system brought out here, considerations have to be madeon cost; power consumption and installation ease [5]. The system presented hereis very easily compatible with the conventional electrical layouts. The systemoffers two modes of operation, firstly Automatic mode, secondly Manual mode.Automatic mode is meant to automate the electrical loads and appliances, usinga control mechanism which has inputs from a Light Dependent Resistor(LDR),Infrared(IR) Receiver, Passive Infrared (PIR) sensor and a temperature sensor,through a microcontroller (here PIC16F877A). The switching of the electricalappliances is controlled through the proposed system, along with the fan speedcontrolling, keeping energy conservation as the major concern. Manual modedoes not change the conventional system much, but allows the user to controlthe switching and fan regulation through an Infrared Ray (IR) remote control.The facility to the user of switching between the two modes will spare the userthe opportunity to slowly realize the importance of the automatic mode (i.e.automation) in energy conservation [6], and get comfortably adapted to it. TheManual mode of operation is also accompanied with wireless remote switchingof the above said appliances, and also their status can be known, through theGlobal System for Mobile (GSM) Communication technology [3], which furthersupports to the motive of the system.

2. Architecture of the Proposed System

The proposed system is comprised of two modes, Automatic and Manualmode respectively. Automatic mode is composed of a sensor unit (LDR, PIR[7], IR and temperature sensor) and PIC microcontroller 16F877A as the centralcontrol unit. Manual mode consists of an IR transmitter which is driven by thePIC microcontroller 16F876A to control a receiver integrated with the centralunit in order to control the electrical appliances with the IR remote (transmitter)[8]. In this system the user has the flexibility to preset the fan speed according totheir comfort level. Additionally the system occupies a GSM modem to monitorand control the home electrical utilizations remotely. Figure 1 and 2 show theoverall system, as explained in the briefing above, to give a better imaginationof the architecture of the system.

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Figure 1: Proposed System Architec-ture with IR Remote

Figure 2: Proposed System Architec-ture with GSM Modem

3. System Implementation

The Process flow of the “Automatic” and “Manual” mode is provided infigure 3 and 4 respectively.

3.1. Automatic Mode

In this mode, an IR sensor (namely TSOP 38238) is placed at the entrancedoor. The receiver gives an output as active LOW in response to the IR lightof frequency 38 KHz, which it receives from an IR transmitter placed rightopposite to it, connected to a 555 timer to produce the IR light of the desiredfrequency. When the output of the receiver goes active HIGH, it is inferred thata person has crossed the door.

The PIR sensor is placed inside the room to detect motion. It detects theheat generated by the human body during body movements through its Fresnellens, and in turn generates certain voltage corresponding to the same. Theoutputs of both the IR receiver at the door and the PIR sensor are comparedto infer the entry or exit of a person, into or from the house. Figure 5 shows atypical PIR sensor.

If the person exits the room, all the electric appliances are turned off by notfiring the TRIAC. Else, the central control unit PIC16F877A reads the voltagedrop at the LDR to decide between night time (lumen intensity is not enoughfor clear visibility) and day time. The inference of night time switches ON thelighting by firing the TRIAC.

The control unit also reads the voltage drop at LM35DZ, which is a “Centi-grade calibrated” temperature sensor with sensing range of 0 to 100 degreecentigrade. The user is given the flexibility to set one’s Comfort Mode from thethree modes offered, which are Cool, Normal, Warm and also the correspond-ing temperatures. Each mode has different relations between the temperaturesensed and the speed of the fan. Hence the temperature sensed is comparedwith the Comfort mode settings to run the fan at different speeds by firing theTRIAC at different corresponding times. In figure 6, Liquid Crystal Display(LCD) shows the current temperature and the speed of the fan for the Normal

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Figure 3: Automatic Mode Figure 4: Manual Mode

comfort mode. Zero sensing mechanism is used in this project which interruptsthe central control unit during that particular instant when the sinusoidal in-put Alternating Current (AC) becomes zero, and this sensed time is used tocalculate the exact delay times after which the respective TRIACs are to befired.

3.2. Manual Mode

In manual mode the central control unit does not control the switching ofthe electric appliances or the speed of the fan using its sensor output. Instead,these actions are controlled through the IR pulses received by an IR receiver(different from the one used at the door in automatic mode) from an IR RemoteController, which has dedicated buttons on it for each of these functions. Thecontrol unit used for the remote controller is a microcontroller (PIC 16F876A),which through its control logic generates unique IR pulses of different burst

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Figure 5: PIR Sensor

Figure 6: LCD Output

lengths for each of the remote controller buttons. The electrical appliances canalso be controlled manually in this mode, using soft touch switches. Figure 7shows how a single burst of the IR data transmitted by the IR remote controllerlooks. The frequency and duty cycle of a single pulse is 38 kHz and 50 percentrespectively. The IR receiver initially gives the output as active HIGH, andtakes a delay (td) of 7 times the time period (To) of 1 pulse, which is (1/38kHz) seconds, to give the output as active LOW. The output of the receiverremains LOW for 6 times the time period of 1 pulse after the IR burst getsover. A single burst contains 10 pulses. For each of its buttons, the IR remotecontroller transmits unique IR data by varying the no: of bursts. For example,for button 1, the IR remote controller transmits 100 bursts that is shown infigure 8 causing the output of the receiver to go active LOW 100 times. Asthe output of the receiver is connected with the external interrupt pin (RB0) ofPIC 16F877A, the transmission for button 1 causes 100 interrupts to the centralcontrol unit. For button 2 (shown in figure 9), IR remote controller transmits200 bursts, causing 200 interrupts on the receiving side. Similarly, the no. ofbursts transmitted for each button on IR remote controller varies, causing eachbutton to have its own unique IR data.

Figure 7: Format of a Single Burst of IR Data

Again in manual mode, after every 15 minutes, the sensors check for thepresence of a person in the room. If the person is absent, the central controlunit checks if the appliances are ON by checking the particular ports of themicrocontroller 16F877A, in which case the microcontroller sends a SMS (ShortMessage Service) to the user’s mobile number showing the current status ofthe electric appliances through the GSM modem, and keeps sending similarmessages after every 15 minutes until the user sends an “OFF” command tothe GSM modem, which turns off the appliances, saving energy. Figure 10 and

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Figure 8: Format of Transmitted and Received IR Data for Button 1

Figure 9: Format of Transmitted and Received IR Data for Button 2

11 show the message format which is sent to the user mobile number, after the15 minutes (when the timer TMRO gets overflowed), showing the status of theappliances, and then “OFF” command will be sent from the mobile of the userback to the control unit 16F877A through a GSM modem.

Figure 10: Message sent by the GSMmodem to the user

Figure 11: User command to switchOFF the appliances

4. Circuitry Discussion and Briefing

Figure 12 shows the final implemented circuit for the central control unit.The proposed system is designed with PIC 16F877A, as central logic unit,

with analog inputs from LDR at its AN0 pin and from the temperature sensorat AN1. The digital inputs from sensors include inputs from the IR receiver atdoor and PIR sensor at RC3 and RD0 pins, respectively, while the digital inputfrom the IR receiver for remote control is acquired by the external interruptpin INT0. The three buttons for settings are placed at RD1, RD2 and RD3.The TX and RX pins are dedicated for the RS232 communication with the GSMmodem, while a major part of PORTB is occupied for interfacing with the LCD.The RS232 serial communication with the GSM modem is established througha MAX232 IC which is actually a voltage level converter. The zero crossing

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Figure 12: Overall Circuit of Control Unit

sensing is detected by the Port Change Interrupt at RB7, while the firing of therespective TRIACs is controlled by the pins RD4 and RD5. Finally, RC4 andRC5 pins take input from the soft touch switches for manual switching of theelectrical appliances, in the Manual Mode. The fifteen minutes timer operationis implemented by the TMR0 timer register of the microcontroller. The clockused for the operation is a High Speed crystal oscillator of 16 MHz.

5. Conclusion

The proposed architecture has a unique feature of controlling the fan speedaccording to the comfort level of the user automatically by taking feedback ofenvironment temperature which is in fact a distinctive feature of air conditioner(AC). Along with this feature it conveys some other decent characteristics whichinclude remote controller operation and controlling the appliances automaticallyif there is no human present. This system is designed by taking concern of boththe power saving and the comfort of the user. The system implementation costis also in the range of the general user class.

References

[1] V. K. Bhansali, “Energy conservation in India - challenges and achieve-ments”, IEEE/IAS International Conference on Industrial Automation andControl, pp. 365-372, 1995.

[2] Kamalapur G D, Udaykumar R Y, “Electrical Energy conservation in In-dia - Challenges and Achievements”, International Conference on Control,Automation, Communication and Energy Conservation, pp. 1-5, 2009.

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[3] H. ElKamchouchi, Ahmed ElShafee, “Design and Prototype Implementa-tion of SMS Based Home Automation System”, IEEE International Con-ference on Electronics Design, Systems and Application, pp. 162-167, 2012.

[4] M. Van Der Werff, X. Gui, W.L. Xu, “A Mobile-Based Home AutomationSystem”, 2nd International Conference on Mobile Technology, Applicationsand Systems, pp. 5, 2005.

[5] Yanbo Zhao, Zhaohui Ye, “A Low Cost GSM/GPRS Based Wireless HomeSecurity System”, IEEE Transactions on Consumer Electronnics, vol. 54,no. 2, pp. 567-572, 2008.

[6] D. Tejani, A.M.A.H. Al-Kuwari, V. Potdar, “Energy conservation in asmart home”, Proceedings of the 5th IEEE International Conference onDigital Ecosystems and Technologies, pp. 241-246, 2011.

[7] Bai Ying-Wen, Cheng Chen-Chien, Xie Zi-Li, “Use of a time-variation ul-trasonic signal and PIR sensors to enhance the sensing reliability of anembedded surveillance system”, 26th Annual IEEE Canadian Conferenceon Electrical and Computer Engineering , pp. 1-6, 2013.

[8] Park Yunjung; Lee Minho, “effective smart remote controller based oninvisible IR-LED using image processing”, IEEE International Conferenceon Consumer Electronics, pp. 434-435, 2013.

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