Arduino Based Industrial appliances control system by decoding dual tone multi frequency signals on GSM / CDMA network. Submitted by:

contents Introduction Block diagram Power supply Arduino 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 arduino 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 Timer Serial COM Port Microcontroller CPU A single chip

Image of development board

Features of Duemalinove The Duemalinove board features an Atmel ATmega328 microcontroller operating at 5 V with 2 Kb of RAM, 32 Kb of flash memory for storing programs and 1 Kb of EEPROM for storing parameters. The clock speed is 16 MHz, which translates to about executing about 300,000 lines of C source code per second

…..contd The Arduino programming language is a simplified version of C/C++. If you know C, programming the Arduino will be familiar. If you do not know C, no need to worry as only a few commands are needed to perform useful functions.

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.

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 Arduino 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.