DTMF based load control


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load control by DTMF technique

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DTMF based load control

  1. 1. Submitted by:
  2. 2.  Introduction  Block diagram  Power supply  Microcontroller  DTMF decoder  Relay  Relay driver  Software requirements  Schematic & Working of the project  Advantages  Applications  Future scope  Conclusion
  3. 3.  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
  4. 4.  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.
  5. 5.  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.
  6. 6.  It is a smaller computer  Has on-chip RAM, ROM, I/O ports... RAM ROM I/O Port Timer Serial COM Port Microcontroller CPU A single chip
  7. 7. CPU On-chip RAM On-chip ROM for program code 4 I/O Ports Timer 0 Serial Port OSC Interrup t Control External interrupts Timer 1 Timer/Counter Bus Control TxD RxDP0 P1 P2 P3 Address/Data Counter Inputs
  8. 8.  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
  9. 9. +5V 30 pF 30 pF 8.2 K 10 uF + 11.0592 MHz EA/VPP X1 X2 RST 31 19 18 9
  10. 10.  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.
  11. 11.  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.
  12. 12.  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.
  13. 13.  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
  14. 14.  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.
  15. 15.  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.
  16. 16.  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.
  17. 17.  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.
  18. 18.  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.
  19. 19.  Using DTMF technology the loads can be operated from any where.
  20. 20.  This project is used to control the loads in --industries --home --agriculture etc..
  21. 21. Thus by using DTMF technology and microcontroller the loads can be operated from any place.