Dtmf Mobile Phone Controlled Pc

Topics: Direct current, Rectifier, Microcontroller Pages: 14 (3532 words) Published: January 27, 2011

.In general all the PCs are controlled by mouse but we can perform those mouse actions by using a mobile with the help of DTMF (Dual Tone Multiple Frequency) technology. Dual-tone multi-frequency signaling (DTMF) is used for telecommunication signaling over analog telephone lines in the voice-frequency band between telephone handsets and other communications devices and the switching center. This project consists of a mobile phone (or land phone) for controlling the PC and Microcontroller unit. User has to operate the PC within the visible distance. This project consists of Microcontroller based control system attached to the PC. The term microcomputer is used to describe a system that includes a minimum of a microprocessor, program memory, data memory, and input/output (I/O). Some microcomputer systems include additional components such as timers, counters, analogue-to-digital converters and so on. Thus, a microcomputer system can be anything from a large computer having hard disks, floppy disks and printers, to a single chip computer system. Here the receiver at the computer end is capable of receiving a set of command instructions in the form of DTMF tones and performs the necessary actions like left click, right click etc.

1. Remote controlling of the computer.
2. Tone enabled operation instructions.
3. Controlling can be done from any phone
4. Easy and immediate access to PC.


Figure 1: DTMF mobile phone controlled PC Block Diagram

The block diagram of DTMF mobile phone controlled PC is shown in figure 1. It consists of a DTMF decoder to decode the signals produced by mobile phone and gives a binary output which is equivalent to the key pressed and this is given to the microcontroller, which produces the instructions according to the program dumped in it. These instructions are given to the PC through MAX232. A software running inside the PC will read the instructions from microcontroller and perform the specific operation allotted.

Regulated power supply is used to convert the 230v ac to 5v dc voltage. The MAX232 is used to increase the voltage level of instruction signals which are suitable to PC. Crystal oscillator is used to produce the timing signals for microcontroller. LED Indicators are used to check whether the microcontroller receiving the information or not. The detailed explanation of each block is explained in later chapters. 3. REGULATED POWER SUPPLY

The main aim of RPS is to convert AC voltage to DC voltage. Its block diagram is as shown below Input is 230 volts A.C




Output is 5 volts D.C Figure 2: Regulated Power Supply
The process of transforming energy from one device to another is called transformation. For transforming energy we use transformers. TRANSFORMER:
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors with out changing its frequency. A varying current in the first or primary winding creates a varying magnetic flux in the transformer's core, and thus a varying magnetic field through the secondary winding. This varying magnetic field induces a varying electromotive force (EMF) or "voltage" in the secondary winding. This effect is called mutual induction. The input coil is called the primary winding the output coil is the secondary winding.

Figure 3: Transformer
The voltage induced in the secondary is determined by the TURN...
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