Home Automation using Power Lines Communication
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Transcript of Home Automation using Power Lines Communication
“PC/GSM based Home Automation System Using the concept of Power Line
Communication”
What is Home Automation?Home automation is automation of the home, housework or household activity. Home automation may include •centralized control of lighting, •HVAC (heating, ventilation and air conditioning), •appliances, security locks of gates and doors and other systems, to provide improved convenience, comfort, energy efficiency and security.
What Can Home Automation Do?• Turning lights down / off at night.• Operating television, hot water heater, kettle, toaster etc. ready for your use.
• Opening the Main gate.• Working with intelligent electrical white goods e.g. washing machine, fridge, Air Conditioners, microwave etc.
The primary elements of a HA System• The operating system (for example, a computer, Mobile).• The device being operated (for example, a light or furnace)• The interface, or link, between the user and the device. An interface can be a button, a keypad, a sensor and so on.
Using Power Line Communication• In the latest generation of home automation systems, appliances can exchange information by transmitting data over the domestic mains wiring. Hence
• No need to install extra control cables • appliances can be connected to the network simply by plugging them into the nearest wall socket.
• Microcontroller can easily be used in conjunction with X-10 technology to create home automation applications. The PIC16F877A can be selected for this application because of its versatility as a general purpose microcontroller.
Power Line Communication(.)• A system for carrying data on a conductor used for electric power transmission.
• Electrical power is transmitted over high voltage transmission lines and is distributed all over the medium.
• All power-lines communications systems are operated by impressing a modulated carrier signal on the wiring system.
Power Line Communication• Compatibility with existing homes and wiring. This type of system requires no new wiring.
• Different types of power-lines communications use different frequency bands
• X-10 is a communication protocol designed for sending signals over 230 VAC wiring.
• X-10 uses high frequency bursts timed with zero crossing to represent digital information.
Modules Designed• Power Supply• Transmitter Board• Receiver Board• DTMF Receiver Board • Relay Based Circuit Board
Block Diagaram
POWER SUPPLY
The power supply system has an input which is normally ac and, a dc output. This dc output is used to power some form of electronic circuitry.
The input could be the 220V 50Hz mains supply .
POWER SUPPLY SYSTEM
Breaking this system down , the ac voltage changed and ac to dc conversion. A simple dc regulation circuitry will be required to convert it into to regulated DC
AC RECTIFICATION
Full wave bridge rectifier shown there are 2 diode ‘drops’ in the dc path.
Capacitors (~1nF each) across the bridge diodes reduce high frequency noise.
THE SMOOTHING CAPACITOR
The output from the transformer and rectifiers follows the sine waveform.
The smoothing capacitor ‘fills in’ the low voltage portions, so reducing the ripple voltage amplitude.
THREE TERMINAL REGULATORS
DC power regulators are readily available, for either positive or negative power supplies.
These regulators need capacitors located close to the devices.
Low, medium and high power versions are available
POSITIVE fixed regulator NEGATIVE fixed regulator
Power Supply Schematic
Transmitter• The controller used in transmitter board is PIC16F877A• The signal to turn ON or OFF is issued using Transmitter board that can be from PC, or PUSH button the transmitter
• The signal is then transferred using TW523 Transmitter module on to the Power Line
• The Signal moves through the each end of the power line turning Device status ON or OFF
Transmitter Block Diagram
Connecting the LCD
Transmitter Schematic
Connecting PC with Transmitter• VB.NET forms are designed in the PC Windows and this can provide the interface to the Transmitter Circuitry
• The interface of forms to the circuit is done using the serial port of the system (Serial to USB converter can also be used if there is no serial port in the system).
Serial Port Communication
• Max232 is used as an interface between devices being operated at different clock speeds
9 pins Serial Connector
Receiver Module• The receiver module receives the signal from power line’s TW523 module and then turns ON or OFF corresponding device.
• The receiver modules receives the DTMF on mt8870 chip that is connected with it.
• MT8870 informs the Controller with their corresponding value that was pressed already from the transmitter
MT8870 Board• The MT8870 chip is used for receiving and decoding DTMF signals received from the Mobile phone or the TW523 travelling through the Power Lines
• As DTMF can not be directly Understood by Microcontroller so this intermediate Chip is required
• The Mobile phone is connected with this separate board containing the MT8870
Mobile Connector• One of the wire (Left/Right) is used as input to the controller• When a button is pressed a corresponding tone is fed to the MT8870 using this 2.5mm connector
• And corresponding relay can be turnedon or off
• One end of hands free is connected with the DTMF input of the MT8870 and the other end is free.
• The 2.5mm connector is connected with the mobile phone.
• A connection can be automatically made with this mobile by dialing its number keeping it on auto answering mode , so when a digit is pressed after a corresponding relay can be ON or OFF
MT8870 Configuration
MT8870 receiver Board
• The Four QN pins are used for describing the different Input Combinations e.g. 0010 corresponds to 2 and 0100 corresponds 4 and so on
• The StD pin is of very importance from the programming point of view when ever a change in input comes a high to low signal appears at this pin indicating that a change in input occurs
Relay Units• A relay is an electromagnetic switch which is used to switch High Voltage/Current using Low power circuits.
• Relay isolates low power circuits from high power circuits. It is activated by energizing a coil wounded on a soft iron core.
Note :A relay should not be directly connected to a microcontroller, it needs a driving circuit.
• A microcontroller is not able to supply current required for the working of a relay. The maximum current that a PIC Microcontroller can source or sink is 25mA while a relay needs about 50 – 100mA current.
• A relay is activated by energizing its coil. Microcontroller may stop working by the negative voltages produced in the relay due to its back emf.
Output Relay Board• Output Relay board consists of two pairs of relays with the Bulb/Tube light connected with each of them
• The output of the receiver is used to derive the one of the above relays
• The output of the PIC16F877A can not derive more then 20mA so its used to turn on a NPN transistor which can then provide enough current to derive the relay
• NPN Transistor is used as a switch as the base is connected with the corresponding PIN of the controller
Interfacing with Microcontroller
References• http://www.vbtutor.net/vb6/lesson7.html
• D. Rye, “X-10 Powerhouse Technical Note”, [Online Document], 04 Mar 2003, [cited 21 Jun 2005], Available HTTP: http://www.x10.com/support/technology1.htm
• [2] Scott Edwards Electronics, “BPI-216 Serial LCD Modules” [Online Document], 01 July 2000, [cited 01 July 2005], Available HTTP: http://info.hobbyengineering.com/specs/PX-BPI-216.pdf
• http://techhouse.brown.edu/~dmorris/projects/tutorials/transistor.switches.pdf
• [3] Microchip Technologies, “PIC16F87XA Data Sheet 28/40/44-Pin Enhanced Flash Microcontrollers,” [Online Document], 19 July 2003, [cited 25 Jun 2005], Available HTTP: http://ww1.microchip.com/downloads/en/DeviceDoc/39582b.pdf