HOW TO MAKE WIRELESS ROBOT

        HOW TO MAKE WIRELESS ROBOT


Robotics can be defined as the science or study of the technology primarily associated with the design, fabrication, theory, and application of robots.I will explain the simple wireless robot using ASK (Amplitude Shift Keying) based Tx/Rx (transmitter/receiver) pair or RF MODULE operating at 434 MHZ.
This is a very simple project, and can easily be expanded to transmit temperature data, alarm status, remote control signals, and other information over wireless links.

TRANSMITTER CIRCUIT DIAGRAM:

The encoder IC takes in parallel data which is to be transmitted, packages it into serial format and then transmits it with the help of the RF transmitter module. At the receiver end the decoder IC receives the signal via the RF receiver module, decodes the serial data and reproduces the original data in the parallel format.
THE RECEIVER CIRCUIT DIAGRAM:

in order to control say a dc motor, we require 2 bits of information (switching it on/off) while we need 4 bits of information to control 2 motors. HT12E and HT12D are 4 channel encoder/decoder ICs directly compatible with the specified RF module.

In order to drive motors, we would need to connect a suitable motor driver at the output of the decoder IC. Bcoz the current is not sufficient to drive the motor. The motor driver circuit can consist of a relay, transistorized H-Bridge or motor driver ICs like the L293D, L298 etc.

MOTOR DRIVEING CIRCUIT:

RF module based Remote control (DTMF IC)

RF module based Remote control (DTMF IC) 

Remote controls are  part of an electronics device used for operating the electronics device remotely. Remote control has continuously evolved and advanced over recent years.The technologies like bluetooth connectivity, motion sensor enabled capabilities and voice control have been included to remote controls.

Here we are going to build a remote control. This remote control could be used for controlling  robo cars, helicopters or for switching home appliances.Normal remote controls use IR transmission,but in this case RF  transmission is used. Transmission through RF is better than IR (infrared) because of many reasons. Firstly, signals through RF can travel through larger distances making it suitable for long range applications. Also, while IR mostly operates in line-of-sight mode, RF signals can travel even when there is an obstruction between transmitter & receiver. Next, RF transmission is more strong and reliable than IR transmission.

 Component required :

·         RF  module:                                                                                                                            

For the transmission of control signals (here DTMF signals) we need a RF transmitter and a receiver. FM transmitter and receiver pair or any kind of RF Tx Rx module will do. In this remote control ASK modulation based RF transmitter & receiver pair are used for transmitting signals .                                                                 .

·         IC UM91214b( DTMF TONE GENERATOR):

This is a single single chip IC with an on-chip oscillator for a 3.58Mhz crystal.This is capable of generating Dialing Pulse(DP) and Dual Tone Multi Frequency(DTMF).But we don't need to be bothered about DP generation.All you need is just to generate DTMF signals.A keypad interface is necessary to generate different DTMF signals.The advantage of using UM91214b is its inbuilt keypad interface facility. You just have to connect the  keypad pins to UM91214's Row & Column pins. 

   A simple circuit of Um91214 for the purpose of generating only dtmf  is shown:

   When a keypad button is pressed, a DTMF tone is generated on pin7 accordingly. To check whether DTMF tone is being generated or not, simply just connect a 8ohm speaker,press a button and hear the tone.

 KEYPAD :

   

 A 3.58MHZ crystal .: 

DTMF decoder IC:

Receiving the DTMF tone from the RF receiver we need to decode it to binary or bcd. A commonly used DTMF decoder ic is cm8870 or MT8870 or XX9370. IC XX8870 takes DTMF tone as input, decodes the tone to binary and outs it to its pin11 to pin14.

Circuit diagram for cm8870 is shown bellow:

In this picture pin11 to pin14 (named as D0,D1,D2,D3) are  output pins,if the DTMF tone for key1 is pressed output will be 0001(pin14=0,pin13=0,pin12=0,pin11=1) .

Key Tone	Output Logic
	D3(pin14)	D2(pin13)	D1(pin12)	D0(pin11)
1	0	0	0	1
2	0	0	1	0
3	0	0	1	1
4	0	1	0	0
5	0	1	0	1
6	0	1	1	0
7	0	1	1	1
8	1	0	0	0
9	1	0	0	1
0	1	0	1	0
*	1	0	1	1
#	1	1	0	0
A	1	1	0	1
B	1	1	1	0
C	1	1	1	1
D	0	0	0	0

 ·                     Circuit diagram of the transmitter part of the remote control :

·                     Circuit diagram of  receiver part of the remote control :