Welcome
To
Lords institute of engineering and technology
Mechanical Department
Batch 2006-10
Mini project
on
 Automatic control of railway
gate
WHAT IS AN EMBEDDED
SYSTEM?
II In built
Embedded System =
Computer Inside a Product
Embedded System
 Embedded system is combination of hardware &
software for specific application.
 Embedded system means the processor is embedded
into that application.
 An embedded product uses a microprocessor or
microcontroller to do one task only.
 In an embedded system, there is only one application
software that is typically burned into ROM.
How an embedded system works..?
 It works with the help of both the hardware
and software requirements
 Hardware: processor, memories, peripherals,
power supply etc..,
 Software: assembly language program (ALP)
like c, c++ ..,
Types of embedded systems
 Simple embedded system
ex: small electrical equipments
completes its work with in the
approximated time
 Complex embedded system
ex: used in military missiles for
target based system
Examples of embedded systems
• Electronic devices in the kitchen
E.g.: bread machines, food processors,
microwave ovens
• Living Rooms
E.g.: televisions, stereos, remote controls
• Work places
E.g.: fax, pagers, laser printers, cash
registers, credit card readers
Automotive & Industrial
Chapter -2
Micro controller
Micro controller
 The first micro controller was implemented in
1968 by a car company wolves wagons in
their cars.
 The 1st micro controller (8048) was developed
by Intel in 1976.
 Found in 1984.
 Corporate headquarters located in San Jose, California.
AVR basic architecture was developed by two students ‘Alf-
Egil Bogen’and ‘Vegard Wollan’ at the Norwegian Institute of
Technology.
 IP Core was sold to Atmel by Alf and Vegard
ATMEL 
AT89C, AT90S, AT Mega, ATCAN
AT Mega
AT Mega 8 , AT Mega 8515
AT Mega 8535, AT Mega 16
AT Mega 32, AT Mega 162,…………
AT Mega Microcontroller
 AT represents the name of the manufacturing
company “ATMEL”.
 ATMEL
 Advanced Technology Memory End Logic
 MEGA
Clock Frequency of the micro controller (1MHz)
Features of ATMega8515











40 Pin IC, PDIP package
High-performance, Low-power AVR 8-bit Microcontroller
RISC Architecture
130 Powerful Instructions – Most Single Clock Cycle
Execution
32 x 8 General Purpose Working Registers
Program and Data Memories
8K Bytes of In-System Self-programmable Flash
512 Bytes EEPROM
Endurance: 100,000 Write/Erase Cycles
512 Bytes Internal SRAM
35 Programmable I/O Lines
Pin configuration
 From 1-40
1
40
39
Port B
Vcc
Port A
8
Reset
9
ATMEGA
32
ICP
10
8515
31
30
ALE
29
28
OC1B
Port D
XTAL2
XTAL1
GND
17
18
19
20
Port C
21
Memories in AT Mega
 Data Memory  Temporary
 EEPROM
 Permanent
 Flash Memory/Programmable Memory 
Permanent
Data Memory
 General Purpose Registers (G.P.R)
 32 registers  R0 to R31
 Each 8 bits
 I/O Registers  64  Each 8 bits
 SRAM  512 bytes
Memory Mapping of
Data Memory
 $0000
$001F
G. P. R
$0020
I/O Registers
$005F
$0060
SRAM
$025F
Register Pairs /
Indirect Addressing
R27
 R
r
R29
R28
R31
R30
 R

$025F
R26
Rah Ral
x pair
y pair
z pair
$02
$5F
 R27
 R26
Status Register
 It is an 8 bit Special register where each bit in the
register represents a Flag.
Zero
Interrupt
Bit
Store
Negative
Half
carry
Sign
Over
flow
Zero
Chapter - 3
IR sensors
Working of IR pairs
 Power supply
IR transmitter
IR receiver
comparator
DETECTION FACTORS:
 Six factors typically affect the Probability of
Detection (Pd) of most area surveillance
(volumetric) sensors, although to varying degrees.






These are the:
1) Amount and pattern of emitted energy;
2) Size of the object;
3) Distance to the object;
4) Speed of the object;
5) Direction of movement
SENSORS APPLICATIONS:
 Most sensors have been designed with a specific




application in mind.
The environment categorizes these applications
where they are most commonly employed.
The two basic environments or categories are
exterior and interior.
Each of the two basic categories has a number of
sub-sets, such as fence, door, window, hallway, and
room.
The first two of the following set of graphics show a
“FREE TREE” illustration of the sensors most
applicable to the these two environments.
Chapter - 4
 Stepper motor
Stepper Motor History :
Definition :
Construction and Operation :
Types of Stepper Motor :
Real World Stepper Motor
Picture of stepper motor
Circuit connections
Operation principle of stepper motor
PRECAUTION
 If the stepper motor moves slightly and/or queers hack and





forth, there are a number of possible causes.
If you are using a battery power supply, the batteries may be too
weak to power the motor properly.
Note; Batteries wear out quickly because the current draw from
stepper motors is usually high.
If you substituted another transistor for the TIP120 NPN
transistor, the substitute transistor may not be switching
properly or the current load of the stepper motor may be too
great. Solution; use TIPO120 transistors.
You have the stepper motor improperly wired into the circuit.
Check the coils using an ohmmeter and rewire if necessary.
The pulse frequency is too high. If the pulses to the stepper
moor are going faster that the motor can react, the motor will
malfunction.
Conclusion
 This is to conclude that this project Automatic control
of railway gate is useful to know when the train is
passes through the gate, and to close or open the gate
automatically as the train is about to reach the gate.
Through which accidents can be avoided as people
tend to cross the track in spite the gate is being closed