mobile controlled robot
Post on 12-Jul-2015
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Mobile controlled robot
Mobile controlled robotUsing AT Mega8 c
Introduction This is the robot whose actions can be controlled by a mobile phone from all over the world using the DTMF signaling.Use of mobile phones for robotic controls provide working range as large as the coverage area of the service provider and no interference with other controllers.
What is DTMFDTMF (Dual tone multi frequency) as the name suggests uses a combination of two sine wave tones to represent a key dialed on a pushbutton or DTMF keypad. These tones are called row and column frequencies as they correspond to the layout of a telephone keypad.
Hardware Components RequiredA microcontroller (ATMega8)Transmitter and receiver mobile phonesDTMF decoder IC (MT8870)DC motorMotor driver IC (L293D)WheelsPower adopter
ATMega8 Development Board
DTMF Keypad LayoutA DTMF keypad (generator or encoder) generates a sinusoidal tone which is mixture of the row and column frequencies.The row and column frequencies corresponding to a DTMF keypad have been indicated in the above figure.DTMF tones are able to represent one of the 16 different states or symbols on the keypad.
DTMF Decoder IC (MT8870)On pressing any key say key 1, a combination of frequencies 1209 and 697 Hz will be generated by keypad which is fed to IC through sound converter which in turn produce the output 0001 (Q1, Q2, Q3, Q4). Following table shows output of remaining keys.
Motor Driver IC (L293D)It is required to supply sufficient current to motors as microcontrollers cant supply that much current.It is a dual H-Bridge motor means it can drive two DC motors simultaneously in both clockwise and anticlockwise direction.Its input terminals are controlled by the microcontroller. It also includes the protection circuit against back EMF.
MicrocontrollerMT8870 DTMF Decoder ICIC OutputAudio jackBoot sectionRobot chassisWheel
Description The robot is controlled by a mobile phone that makes call to the mobile phone attached to the robot and in the course of the call, if any button is pressed the corresponding DTMF freq. will be heard at the other end.DTMF assigns a specific frequency (consisting of two separate tones) to each key that it can easily be identified by the electronic circuit. The signal generated by the DTMF encoder is the direct algebraic submission, in real time of the amplitudes of two sine(cosine) waves of different frequencies, for example: pressing key5 will send a tone made by adding 1336hz and 770hz to the other end of the mobile
Conti..The received tone is processed by the atmega8 microcontroller with the help of DTMF decoder (MT8870). The decoder decodes the DTMF tone in to its equivalent binary digit and this binary number is send to the microcontroller.The microcontroller is preprogrammed to take a decision for any given input and outputs its decision to motor drivers in order to drive the motors for forward or backward motion or a turn.