INFRA RED CONTROL
this project we will control stepper motor using IR sensors. We will
work use TSOP1738, which will work 38Kh frequency. This project is
very helpful to control home appliances and machinery .tsop 1738
means it work at 38Khz .infra red control project is very popular
project in over all. Commercially it is very useful overall. With
the help of microcontroller. We control the output devices in the
receiver circuit. For this purpose we use two micrcontroller in this
project. Here we use ATMEL microcontroller in the transmitter and
receiver circuit. In atmel series , here we use ic 89s51 as a main
processor.. and ic 89c51 in the receiver circuit as a main receiver
Firsltly we discuss the circuit of infra red transmitter. In this
project out main part of this transmitter is our programming.
the 89s51 microcontroller only two ports are available.. port p1 and
port p3. We connect all the switches and output infra red led is
connected to the port p3
no 12 to pin no 19 is port 1 ouput pins. On this pins we connect a
push to on switches . One point of the switch is connected to the
pins of the microcontroller and other pin is connected to the ground
pin. Port p1.0 and port p1.1 is special pins of this
microcontroller, so we connect a two pull up resistor to this pins.
no 20 is connected to the positive supply. Pin no 10 is connected to
the negative supply. Output infra red led is connected to the port
p3.7. Infra red led is connected to the port p3.7 via pnp
transistor. Here we use pnp transistor because output of the
microcontroller is just negative so it is only capable to drive
the pnp transistor. Pin no 1 is connected to the reset components
via one capacitor and resistor 10 k in series. These two components
auto reset the micrcontroller on power on . We transmit the data
from the microcontroller in the serial communication. . Tx pin of
the micrcontroller is pin 3 of this ic port p3.1. Here port p3.1 is
also connected to the INT0 pin to give a timer 0 intruppt. Here we
use total 10 ouput from the micrcontroller with frequency of 36 k
we explain how we transmit the data from the micrcontroller in
y1: setb p3.7 output data from pin no 11 of the
jb p3.5,nxt9 by this command we check the pressing key
jmp send9 if the p3.5 is not pressing then move to nxt9
if the key is press then go to the send
send9: mov a,#0ah load the accumulator with data 0a h
mov sbuf,a put the data in the sbuf resistor, this
resistor is responsible for serial communication
8051 has a serial data communication circuit that uses register
sbuff to hold data. Register SCON controls data communication,
register PCON controls data rates, and pin RXD and TXD connect to
the serial data network. SBUFF is physically two register. One is
write only and is used to hold data to be transmitted out of the
8051 via TXD. The other is read only and hold received data from
external source via RXD. Both mutually exclusive register use
address 99h .
: SERIAL MODE BIT 0 FOR SELECT MODE
: SERIAL MODE BIT 1 FOR SELECT MODE
SM1 MODE DESCRIPTION
0 0 0 BAUD = f/12
0 1 1 8 BIT BAUD =
1 0 2 9 BIT BAUD =
F/32 OR F/64
1 1 3 9 BIT BAUD =
: MULTIPURPOSE COMMUNICATION BIT
: RECEIVE ENABLE BIT. SET TO 1 TO ENABLE RECEPTION
: TRANSMIT PIN FOR MODE 2 AND 3
: RECEIVE PIN FOR MODE 2 AND 3
T1: TRANSMIT INTRUPPT FLAG. SET TO ONE AT THE END OF BIT 7IN
MODE 0, MUST BE CLEARED BY THE PROGRAM
R1: RECEIVE INTERRUPT FLAG. SET TO ONE AT THE END OF THE BIT 7 IN
Block diagram transmitter- TV remote
CRYSTAL 11.0592 MHz
10 K 11 Pc
50 K 2 Pc VARIABLE
1 K VARIABLE
2.2K 1 Pc
470 OHM 1Pc
22 PF 2 Pc
10 MFD 1 PC
PUSH TO ON SWITCH 2 PC.
STEP DOWN TRANSFORMER 9-0-9
DIODE IN 4007( 4Pc)
10K OHM VARIABLE RESISTOR
Easy to fabricate
WELCOME TO THE WORLD OF THE MICROCONTROLLERS.
Look around. Notice the smart “intelligent” systems? Be it the T.V,
washing machines, video games, telephones, automobiles, aero planes,
power systems, or any application having a LED or a LCD as a user
interface, the control is likely to be in the hands of a micro
Measure and control, that’s where the micro controller is at its
Micro controllers are here to stay. Going by the current trend, it
is obvious that micro controllers will be playing bigger and bigger
roles in the different activities of our lives.
So where does this scenario leave us? Think about it……
The world of Micro controllers
What is the primary difference between a microprocessor and a
micro controller? Unlike the microprocessor, the micro controller
can be considered to be a true “Computer on a chip”.
In addition to the various features like the ALU, PC, SP and
registers found on a microprocessor, the micro controller also
incorporates features like the ROM, RAM, Ports, timers, clock
circuits, counters, reset functions etc.
While the microprocessor is more a general-purpose device, used for
read, write and calculations on data, the micro controller, in
addition to the above functions also controls the environment.
We have used a whole lot of technical terms already! Don’t get
worried about the meanings at this point. We shall understand these
terms as we proceed further
For now just be aware of the fact, that all these terms literally
mean what they say.
Bits and Bytes
Before starting on the 8051, here is a quick run through on the
bits and bytes. The basic unit of data for a computer is a bit. Four
bits make a nibble. Eight bits or two nibbles make a byte. Sixteen
bits or four nibbles or two bytes make a word.
1024 bytes make a kilobyte or 1KB, and 1024 KB make a Mega Byte or
Thus when we talk of an 8-bit register, we mean the register is
capable of holding data of 8 bits only.
The 8051 developed and launched in the early 80`s, is one of the
most popular micro controller in use today. It has a reasonably
large amount of built in ROM and RAM. In addition it has the ability
to access external memory.
The generic term `8x51` is used to define the device. The value of x
defining the kind of ROM, i.e. x=0, indicates none, x=3, indicates
mask ROM, x=7, indicates EPROM and x=9 indicates EEPROM or Flash.
A note on ROM
The early 8051, namely the 8031 was designed without any ROM.
This device could run only with external memory connected to it.
Subsequent developments lead to the development of the PROM or the
programmable ROM. This type had the disadvantage of being highly
The next in line, was the EPROM or Erasable Programmable ROM. These
devices used ultraviolet light erasable memory cells. Thus a program
could be loaded, tested and erased using ultra violet rays. A new
program could then be loaded again.
An improved EPROM was the EEPROM or the electrically erasable PROM.
This does not require ultra violet rays, and memory can be cleared
using circuits within the chip itself.
Finally there is the FLASH, which is an improvement over the EEPROM.
While the terms EEPROM and flash are sometimes used interchangeably,
the difference lies in the fact that flash erases the complete
memory at one stroke, and not act on the individual cells. This
results in reducing the time for erasure.
Understanding the basic features of the 8051 core
Let’s now move on to a practical example. We shall work on a
simple practical application and using the example as a base, shall
explore the various features of the 8051 microcontroller.
Consider an electric circuit as follows,
The positive side (+ve) of the battery is connected to one side of a
switch. The other side of the switch is connected to a bulb or LED
(Light Emitting Diode). The bulb is then connected to a resistor,
and the other end of the resistor is connected to the negative (-ve)
side of the battery.
When the switch is closed or ‘switched on’ the bulb glows. When the
Electronics : By V.K. Mehta
Circuit : By K.R. Botkar
3. Switch And
Protection : By B.V.S. Rao
Electronics : By S.M. Rai & M.S.
for you : June, 2004
Philips Semiconductor June 2001
microcontroller programming and PCB designing
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