Home Security System and watering the garden using

embedded system

SRI VENKATESWARA COLLEGE OF ENGINEERING AND TECHNOLOGY

Saroj yadavR.M Neema

Objective

• Develop a security system that can be accessed by a touch-tone phone as well as a keypad.

• Ability to lock or unlock the door from a remote location.

• Provide the illusion that someone is home.

Introduction for automation• First patented by Nikola Tesla in 1898.• Automation of domestic, HVAC and other

systems, to provide improved convenience, comfort, energy efficiency and security.

• Devices may be connected through the internet or wireless personal network.

Block Diagram for security

Keypad DTMFReceiver

Touch-tone phone

LightControls

ProximitySensors

GasSensors

Micro-controller

sensors

House Controls

User Interfaces

7 8 94 65

31#

2* 0

PIR Sensor

Wireless Camera

Block diagram for watering

Power supply• The power supply used is re-

chargable 12V 1.3Ah Li-ion battery for better durability and higher performance.

• Voltage regulators converts variable DC to fixed DC output voltage that is required for all digital applications.

• The most commonly used ones are LM7805 that gives fixed 5V DC voltage if input voltage is in between 7.5V to 20V.

DTMF Signal Transmission• The system can be controlled from

any remote location through mobile phones using DTMF technology.

• Dual-Tone Multi-Frequency (DTMF) is the generic name for pushbutton telephone signalling equivalent to the Bell System

• The DTMF technique outputs distinct representation of 16 common alphanumeric characters (0-9, A-D, *, #) on the telephone each of which is represented by a pair of tones.

• Pressing a single key (such as '1') will send a sinusoidal tone of the two frequencies (697 and 1209 hertz (Hz))

DTMF Signal Reception and Decoding• The DTMF signal is received by

the receiving cell phone in the system which is connected to the DTMF receiver integrated with digital decoder and band split filter functions(IC HT9170)

• Decoding a DTMF signal involves extracting the two tones in the signal and determining from their value, the intended DTMF digit.

• Highly accurate switched capacitor filters are employed to divide DTMF tone into low and high group signals.

DTMF Data output table from IC HT9170B

IR Proximity sensor

If V+>V- Then Vo = Vcc(High)If V+<V- Then Vo=0(Low)

In absence of obstacle no reflected IR rays are received by photodiode

In presence of obstacle reflected IR rays are received by the photodiode

LM324

PIR(Passive infrared) sensor• PIR is an electronic device which is

used to measure infrared light radiating from a body in its field of view.

• All objects have a certain body temperature and at any specific temperature there is a certain radiation that the body emits, this is called the Black Body Radiation phenomenon.

• When body of different temperature passes from ahead of it, there is an apparent change in the infrared frequency detected due to different temperature of each body.

• The device usually has 2 sensors connected to a differential amplifier so that useless signals are cancelled out and only valid inputs are detected.

Arrangement of component in PIR sensor

Gas sensor• Electrochemical gas sensors are

gas detector that measure the concentration of a target gas by oxidizing or reducing the target gas at an electrode and measuring the resulting current.

• The gas diffuses into the sensor, through the back of the porous membrane to the working electrode where it is oxidized or reduced.

• This electrochemical reaction results in an electric current that passes through the external circuit.

• The gas sensor used can detect the majority of common toxic gases, including CO, H2S, Cl2 & SO2 .

Microcontroller (AT Mega8)• Microcontroller acts as the

Brain of system, which generates desired output for corresponding inputs.

• It is high performance, low power, AVR 8-bit microcontroller.

• It has up to 16 MIPS Throughput at 16 MHz .

• It has 8KB of in system self programmable flash program memory

• It has data retention of 20 years at 85 degree Celsius and 100 years at 25 degree Celsius .

Software implementation

• For the software implementation, we deploy two software packages. First one is the Keil µVision 3.0 & second one is the WinAVR .

• The Keil µVision Debugger accurately simulates on-chip peripherals of AT Mega8 device.

• Simulation helps to understand hardware configurations and avoids time wasted on setup problems.

• The software is written in embedded C language and the HEX file can be dumped into the microcontroller using WinAVR .

CONCLUSION

References• https://www.atmel.com/images/doc2486• https://www.linxtechnologies.com/en/products/modules• https://www.maplin.co.uk/cctv-and-security/wireless-

cameras• https://www.positronindia.in/PT0045.aspx• Robert L.Boylestad and Louis Nashelsky, “Electronic

Devices and Circuit Theory”, 8th Edition, 2010. • S. Y. Harmon & D. W. Gage, “Current Technical

Research Issues of Autonomous Robots Employed In Combat”, 17th Annual Electronics and Aerospace Conference,2011.

• K.S.Fu , R.C.Gonzalez , C.S.G..Lee, Tutorials.

Thank you