DTMF based load control

DTMF BASED REMOTE INDUSTRIAL LOAD

AND/OR AGRICULTURAL PUMP

CONTROLSubmitted by:

CONTENTS Introduction Block diagram Power supply Microcontroller DTMF decoder Relay Relay driver Software requirements Schematic & Working of the project Advantages Applications Future scope Conclusion

INTRODUCTION The main objective of the project is to

control the functioning of the industrial/ agricultural load using wireless technology.

One cell phone will send digitized commands to another cell phone which is in auto answering mode at the receiving end.

The receiving cell phone codes are fed to the microcontroller which is programmed to recognize those codes for operating any kind of load duly interfaced through relays and relay drivers as per the sent commands from the senders mobile

CONTD.. The receiving cell phone codes are

DTMF (dual tone multi frequency) decoded.

DTMF Decoder will identify the key frequency and convert that frequency to digital codes which are then fed to the microcontroller.

BLOCK DIAGRAM

POWER SUPPLY

CONTD.. The 230V AC supply is first stepped

down to 12V AC using a step down transformer.

This is then converted to DC using bridge rectifier.

The AC ripples is filtered out by using a capacitor and given to the input pin of voltage regulator 7805.

At output pin of this regulator we get a constant 5V DC which is used for MC and other ICs in this project.

MICROCONTROLLER It is a smaller computer Has on-chip RAM, ROM, I/O ports...

RAM ROM

I/O Port

TimerSerial COM Port

Microcontroller

CPU

A single chip

BLOCK DIAGRAM OF MC

CPU

On-chip RAM

On-chip ROM for program code

4 I/O Ports

Timer 0

Serial Port

OSC

Interrupt

Control

External interrupts

Timer 1

Timer/Counter

Bus Contr

ol

TxD RxD

P0 P1 P2 P3

Address/Data

Counter Inputs

FEATURES OF MC 8K Bytes of In-System Programmable

(ISP) Flash Memory 4.0V to 5.5V Operating Range Fully Static Operation: 0 Hz to 33 MHz 256 x 8-bit Internal RAM 32 Programmable I/O Lines Three 16-bit Timer/Counters Eight Interrupt Sources Full Duplex UART Serial Channel

PIN DESCRIPTION

POWER ON RESET CIRCUIT +5V

30 pF

30 pF

8.2 K

10 uF+

11.0592 MHz

EA/VPPX1

X2

RST

31

19

18

9

DTMF DECODER This circuit detects the dial tone from a

telephone line and decodes the keypad pressed on the remote telephone.

Two distinct frequency tones make up the DTMF(dual tome multiple frequency), and hence the name.

The dialer and the telephone exchange communicate one way through the DTMF communication.

The tone generator and the tone decoder consist of a complete communication setup.

CONTD.. In this project, IC MT8870DE is used to decode

the input dial tone to the dialed numbers. These digital bits are interfaced to a

microcontroller for any application. Pulse/dial tone method is used in the modern

telephone communication. There is a dial tone generator on the caller side

and a unique tone consisting of two audible tone frequency is generated when the user presses a button.

As an example, 697hz & 1209hz will be generated when key '1' is being pressed on the phone.

a decoder circuit is present on the receiver side, which decodes the tone to a digital code.

RELAY A relay is an electrically operated

switch. Current flowing through the coil of the

relay creates a magnetic field which attracts a lever and changes the switch contacts.

The coil current can be on or off so relays have two switch positions and have double throw (changeover) switch contacts as shown in the diagram.

CONTD.. Relays allow one circuit to switch a

second circuit which can be completely separate from the first.

For example a low voltage battery circuit can use a relay to switch a 230V AC mains circuit.

There is no electrical connection inside the relay between the two circuits, the link is magnetic and mechanical.

To drive relay through MC ULN2003 relay driver IC is used

RELAY DRIVER ULN2003 ULN is Relay driver application The ULN2003 is a monolithic high voltage

and high current Darlington transistor arrays.

It consists of seven NPN Darlington pairs that features high-voltage outputs with common-cathode clamp diode for switching inductive loads.

The collector-current rating of a single Darlington pair is 500mA.

The Darlington pairs may be paralleled for higher current capability.

CONTD.. The ULN functions

as an inverter. If the logic at input

1B is high then the output at its corresponding pin 1C will be low.

SOFTWARE REQUIREMENTS Keil an ARM Company makes C compilers, macro

assemblers, real-time kernels, debuggers,

simulators, integrated environments, evaluation

boards, and emulators for ARM7/ARM9/Cortex-M3,

XC16x/C16x/ST10, 251, and 8051 MCU families.

Compilers are programs used to convert a High

Level Language to object code. Desktop compilers

produce an output object code for the underlying

microprocessor, but not for other microprocessors.

CONTD.. i.e the programs written in one of the HLL like ‘C’ will compile

the code to run on the system for a particular processor like

x86 (underlying microprocessor in the computer).

For example compilers for Dos platform is different from the

Compilers for Unix platform  So if one wants to define a

compiler then compiler is a program that translates source

code into object code.

WORKING OF PROJECT The mobile is connected to the DTMF

decoder IC and a call is made to data mobile from another mobile.

When the network path is formed, any mobile key is pressed.

If 1 is pressed then this tone is decoded to 4 digit data and given to MC by inverting the data.

MC compares this data and at output port which is connected to ULN gets logic high and the output of ULN is low which makes the relay ON. Hence, load 1 will be ON.

ADVANTAGES Using DTMF technology the loads can be

operated from any where.

APPLICATIONS This project is used to control the loads

in --industries --home --agriculture etc..

CONCLUSION

Thus by using DTMF technology and microcontroller the loads can be operated from any place.