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Robotics is an interesting field where every engineer can showcase his creative and technical skills. Pleasing aspect of robotics is that a robot can be made indigenously by anyone. In this competitive world there is need for every enthusiastic, amateur to professional, to make a simple robot having innovated applications and with robust control.

Mobile phones today became an essential entity for one and all and so, for any mobile based application there great reception. In this scenario making a mobile phone operated land rover is a good idea. Conventionally wireless controlled robots utilize RF circuits, which had limitations like limited range, limited frequency ranges and controls. But a mobile phone controlled robot can hold up these limitations. It has a robust control, unlimited range (coverage area of the service provided), no fear of interfering with other controllers and we can have as much as 16controls.

Although the appearance and capabilities of robots vary vastly, all robots share the features of a mechanical, moveable structure under some form of control. This control of robot involves three distinct phases : perception, processing and action. In common preceptors are sensors mounted on the robot, processing is done by on-board microcontroller or processor and task (action) is performed using motors or with some other actuators.

DUAL-TONE MULTI-FREQUENCY (DTMF)

Dual-tone multi-frequency (DTMF) signaling 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. The version of DTMF used for telephone tone dialing is known by the trademarked term Touch-Tone, and is standardized by ITU-T Recommendation Q.23. It is also known in the UK as MF4. Other multi-frequency systems are used for signaling internal to the telephone network.

As a method of in-band signaling, DTMF tones were also used by cable television broadcasters to indicate the start and stop times of local commercial insertion points during station breaks for the benefit of cable companies. Until better out-of-band signaling equipment was developed in the 1990s, fast, unacknowledged , and loud DTMF tone sequences could be heard during the commercial breaks of cable channels in the US and elsewhere.

Circuit Description

Figures shows the block diagram and cicuit diagram of the microcontroller- based robot. The important components of this robot are DTMF decoder, Microcontroller and motor driver.

An MT8870 series dtmf decoder is used here. All types of the mt8870 series use digital counting techniques to detect and decodeall the sixteen DTMF tone pairs in to a four bit code output. The built -in dila tone regection circuit eliminated the need for pre- filtering. When the input signal given at pin2 (IN-) single ended input configuration is recognized to be effective, the correct four bit decode signal of the DTMF tone is transferred to Q1 (pin11) through Q4(pin14) outputs.

The atmega 16 is a low power, 8 bit, cmos microcontroller based on the AVR enhanced RISC architecture. It provides the following feature: 16kb of in system programmable flash memory with read write capabilities, 512bytes of EEPROM, 1KB SRAM, 32 general purpose input/output lines. 32 general purpose working registers. All the 32 registers are directly connected to the arithmetic logic unit, allowing two independent registers to be accessed in one signal instruction executed in one clock cycle. The resulting architecture is more code efficient. Outputs from port pins PD0 through PD3 and PD7 of the microcontroller are fed to inputs IN1 through IN4 and enable pins (EN1 and EN2) of motor driver L293d respectively, to drive geared motors. Switch S1 is used for manual reset.More video