mobile controlled robot
Post on 12-Jul-2015
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Using AT Mega8 µc
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 DTMF
DTMF (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 phones
DTMF decoder IC (MT8870)
DC motor
Motor driver IC (L293D)
Wheels
Power adopter
ATMega8 Development Board
DTMF Keypad Layout A 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
can’t 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.
Overview Microcontroller
MT8870 DTMF
Decoder IC
IC Output
Audio jack
Boot section
Robot chassis
Wheel
Block Diagram
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.
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