In modern electronics, electronics
remote control system is well known system. Infrared remote control kit is
available in the market are quite expensive and if someone wishes to assemble
one, their IC’s may not be easily available. More over for simple ON-OFF
function such as controlling a lamp or fan we do not need very complex circuit.
The IR remote control circuit using photodiode and phototransistor sensor
suffer from major drawback of being affected by ambient light and a very low
range. The IR remote control circuit described here can be used for any simple
ON-OFF function. This system has memories application than other remote control
system. The advantage is that this circuit is absolutely free form ambient
light interference and provides control range of any to focusing lens. The
components use in this system is in so convenient manner that whole assemble is
easier to built. This reduce complex city of the system. When an interface used
between transmitter and receiver in infrared (IR) then it is called IR remote
control. In whole frequency spectrum infrared region just legs behinds visible
spectrum and its frequency range is between 0.1-100 Terahertz. The wavelength is
in terms of micrometer (µm). In IR remotes IR LED is used in transmitters which
emit IR light. In receivers any IR light detector can be used like photo diode,
photo transistor etc.
There are six main blocks which play
important role in TRANSMITTING operation. These blocks are
·
Push
buttons
·
Microcontroller
·
Buffer
·
Ic
555
·
Power
supply
·
Infrared
led
KEYBOARD
Keyboard
is used to access different devices connected on receiver side. Here we are
using 4 x 4 matrix keyboard which is interfaced with microcontroller. Using
this keyboard we can perform sixteen functions. This keyboard is interfaced
with microcontroller when any key pressed it is recognized by microcontroller.
MICROCONTROLLER
Microcontroller is heart of both
transmitter and receiver. Here we are using Atmel 89C51 which is compatible to
Intel 8051 instruction set and in this we can fuse program using serial
cable. Keyboard is interfaced with it.
When any key is pressed in keyboard microcontroller generates specific code
which corresponds to key pressed and transmits it.
POWER SUPPLY
The voltage required to operate is +5V
(regulated) and +9V (raw). The regulated +5V is generated using IC7805. The
input for this regulator IC is rectified and the filters from full wave
rectifier and capacitor filter. The output is obtained and is given to the
microcontroller, buffer, infrared led and Ic 555.
IC 555
The code from microcontroller is given
to reset pin of IC NE555 through AND gate. AND gate will just work as a buffer.
IC 555 is connected in astable mode to generate 38 KHz square pulses
continuously. Its operation can be
ON/OFF by reset pin. Means when reset pin is high o/p is ON and vice versa. So
the code generated by micro-controller will be modulated by IR light beam of 38
KHz.
RECEIVER
TSOP 1738
TSOP sensor is used as receiving
block. It recognizes data signal whose carrier is close to its center frequency
of band pass. Here we are using TSOP 1738 which detects 38 kHz infra red
signals. It receives IR rays and demodulates
the code send by removing 38 kHz.
Microcontroller
The microcontroller used here is heart
of receiver circuit. Here microcontroller used is Atmel 89C51 which is
compatible to Intel 8051 instruction set and in this we can fuse program using
serial cable. Demodulated output from TSOP is fed in it and it recognizes the
send data and corresponding to it gives output by glowing led.
Power Supply
The voltage required to operate is +5V
(regulated) and +9V (raw). The regulated +5V is generated using IC7805. The
input for this regulator IC is rectified and the filters from full wave
rectifier and capacitor filter. The output is obtained and is given to the
microcontroller, TSOP sensor and LEDs.
TRANSMITTER
The heart of circuit is 89C51. It does
the main function of generating a specific code for each key when it is
pressed. Micro-controller will continuously scans the key board for any key
press. When any key is pressed controller will detect it. Then it will assign a
specific code to that key and transmit it.
This code is given to reset pin of IC NE555 through AND gate. One end of
AND gate is given is to Vcc and another is connected to output port
of microcontroller. AND gate will just work as a buffer. IC 555 is connected in
astable mode to generate 38 KHz square pulses continuously. Its operation can
be ON/OFF by reset pin. Means when reset pin is high o/p is ON and vice versa.
So the code generated by micro-controller will be modulated by IR light beam of
38KHz. If any key is pressed in keyboard and if the binary value assigned is
0100 0001, it will be transmitted and modulated by IC 555.
RECIEVER
Infrared rays modulated with 38 kHz
are recognized by TSOP 1738. Output pin (pin 3) of TSOP which usually remains
high goes low when any signal is received. Output of TSOP is given to interrupt
pin of microcontroller. When TSOP output goes low an interrupt is made to
microcontroller which forces microcontroller to take the pulses that is
received. Received data is compared with code stored in microcontroller and if
match is found corresponding output goes low which enables the led connected to
glow. All LEDs connected in the output is common anode.
Main components of circuit are
·
89C51
micro controller
·
AND
gate 74LS08
·
IC
NE555
·
4×4
matrix keyboard (total 16 keys)
Keyboard is connected to P1 port as
P1.0 to P1.3 pins serves as rows and P1.4 to P1.7 serves as columns. The serial
data o/p pin of 89C51 (P3.1 (11)) is connected to one i/p of AND gate chip
74LS09. Second i/p of AND gate is tied to Vcc. The o/p of AND gate
drives reset pin (4) of IC-555 which is configured in astable mode. Output of
IC-555 drives IR LED through transistor Q1 of 2N2222A type.
APPLICATONS
Infrared technology, increasingly
present in mainstream applications, holds great potential for enabling people
with a variety of disabilities to access a growing list of information
resources. Already commonly used in remote control of TVs, VCRs and CD players,
infrared technology is also being used and developed for remote control of
environmental control systems, personal computers, and talking signs. For
individuals with mobility impairments, the use of infrared or other wireless
technology can facilitate the operation of information kiosks, environmental
control systems, personal computers and associated peripheral devices. For
individuals with visual impairments, infrared or other wireless communication
technology can enable users to locate and access talking building directories,
street signs, or other assistive navigation devices. Some other applications of
Infrared remote control system are
·
IR
Remote control is used in industries for controlling substations, pump storage
power stations
·
Existing
infrared remote controls can be used to control PC applications. Any
application that supports shortcut keys can be controlled via IR remote controls
from other home devices
APPLICATIONS
·
Augmentative
communication devices
·
Car
locking systems
·
Computers
o
Mouse
o
Keyboards
o
Floppy
disk drives
o
Printers
·
Emergency
response systems
·
Environmental
control systems
o
Windows
o
Doors
o
Lights
o
Curtains
o
Beds
o
Radios
·
Headphones
·
Home
security systems
·
Navigation
systems
·
Signage
·
Telephones
·
TVs,
VCRs, CD players, stereos
·
Toys
0 comments:
Post a Comment