DTMF based load control
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Transcript of 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.