Well you may
have come across many schematics and projects about a cell phone controlled
land rover in many websites. But this is not the same. This article will show
you how to make a cell phone controlled land rover without using a
microcontroller. You read it right we are not going to use any kind of costly
microcontroller for making the rover.
Description
We'll just
need a DTMF decoder MT8870 and a motor driver L293d for making it. So no circuit
complexity, no costly ICs and no programming required.
A DTMF
decoder is a device which takes a signal from the headset line of a cell phone
and gives a 4 bit output corresponding key pressed in the cell phone. Whenever
a key is pressed in the mobile, a sum of two fixed frequency is sent as input
to the decoder IC. This IC converts the number into its corresponding binary
value for example if 3 is pressed its binary value 0011 is produced at the
output.
The motor
driver L293d can control 2 motors bi-directionally and has 4 inputs. The 4
outputs from the decoder IC is fed into the 4 inputs of the motor driver directly
without using complicated circuits.
The Table
below shows you how the Robo works :-
Number Pressed
|
Output of DTMF decoder
|
Input to the Motor driver
|
Right
Motor
Action
|
Left Motor
Action
|
Robot’s Net Movement
|
6
|
0
1 1 0
|
0
1 1 0
|
Forward
|
Forward
|
Forward
|
9
|
1 0 0 1
|
1 0 0 1
|
Reverse
|
Reverse
|
Reverse
|
5
|
0
1 0 1
|
0
1 0 0
|
Forward
|
Reverse
|
Left
|
0
|
1 0 1 0
|
0 0 1 0
|
Reverse
|
Forward
|
Right
|
3
|
0
0 1 1
|
0
0 1 1
|
Stop
|
Stop
|
Stop
|
Components
|
Quantity
|
Resistors
100k
330k
|
2
1
|
Capacitors
22pF
0.1uF
0.47uF
|
2
1
1
|
Crystal
3.57Mhz
|
1
|
ICs
Motor
Driver L293D
DTMF
decoder MT8870
|
1
1
|
DC
Geared Motors 6V
|
2
|
SLA
Battery 6V,4.5Ah
|
1
|
Advantages:-
Well you
must have already come across the usual advantages of cell phone controlled
Robot like, interference free communication, long range, etc. Lets see what’s
more beneficial in this robot.
1. Reduces
circuit complexity.
2. No need
of any Programming.
3. Cost is
highly reduced. Not everyone can afford a microcontroller along with its programmer
and debugger boards.
Circuit Diagram
Front View
Side View
Top View
