Cell Phone Controlled Robot without a Microcontroller

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

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
4	0 1 0 0	0 1 0 0	Forward	Stop	Left
2	0 0 1 0	0 0 1 0	Stop	Forward	Right
0	0 0 0 0	0 0 0 0	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.