worldwide remote device access system

WORLDWIDE REMOTE

REMOTE DEVICE ACCESS SYSTEM

WORLDWIDE REMOTE DEVICE ACCESS SYSTEM

• In this project we can access four devices from anywhere.

• We can on or off the devices with the help

of cell phone.

• User has to dial the the phone no that is attached with with the device.

• User can off or on the device at any time. If he will not press any no. then after 20 sec phone will be disconnected automatically.

DTMF SIGNALS• The DTMF is a popular signaling method

between telephones and switching centers• DTMF is also used for signaling between the

Telephone network and computer networks• The DTMF signals are Transmitted over a

telephone line• Uses speech frequency signals• DTMF signals are the superposition of 2 sine

waves with different frequencies

The DTMF Keypad

1209 Hz 1336 Hz 1477 Hz

697 Hz 1 2 3

770 Hz 4 5 6

852 Hz 7 8 9

941 Hz * 0 #

TONES

TELEPHONE SIGNALING

WAVEFORMS OF DTMF DIGITS

DECODER OUTPUT

BLOCK DIAGRAM

• IN this project we will control four devices with the DTMF technique. These four devices may be your fans, bulbs, motor etc.

PHONE LI NE DECODER PIC(MICROCONTROLLER)

DEVICESPOWER SUPPLY

PARTS USED ARE• PHONE LINE: It will be the medium in which mobile or phone signal

travels

• DECODER: It will decode the mobile signal to appropriate signal that can drive uC.CM8870 is the dtmf decoder used in this project.

• PIC: PIC is a family of Harvard architecture microcontroller made by Microchip Technology, derived from the PIC1640 originally developed by General Instrument's Microelectronics Division. The name PIC initially referred to "Peripheral Interface Controller".

PICs are popular with developers and hobbyists alike due to their low cost, wide availability, large user base, extensive collection of application notes, availability of low cost or free development tools, and serial programming (and re-programming with flash memory) capability.

In this project we will use 16f877A microcontroller.11• POWER SUPPLY: it will provide provide supply of 12v,5v to the uC

and decoder.

• DEVICES: It may include fan, motor, tubelight etc.

ALGORITHM1) WHEN phone will ring PIC will detect the ring and it will hold the phone after ten rings.

2) Then digit from transmitter is decoded by cm8870 and it is sent to PIC.3) If the Code matches with the address of

devices it will switch ON or off the corresponding device.

APPLICATION OF DTMFVoice mailHelpdesksPhone bankingComputer remote loginRemote appliances control etc.Stock broker buy/sell/inquire -using stock exchange listing mnemonicsCredit card verification and inquiryAnswering machine message retrieval

FUTURE SCOPE

• Password protection can be added

• It can also used for controlling the speed of stepper motor.

• DTMFcan also be applied from computer.

it means devices can also be controlled from remote computer via internet.

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