|
|
2. BASIC IDEA
§
GATE
CONTROL
Railways being the cheapest
mode of transportation are preferred over all the other means
.When we go through the daily newspapers we come across many
railway accidents occurring at unmanned railway crossings.
This is mainly due to the carelessness in manual operations or
lack of workers. We, in this project has come up with a
solution for the same. Using simple electronic components we
have tried to automate the control of railway gates. As a
train approaches the railway crossing from either side, the
sensors placed at a certain distance from the gate detects the
approaching train and accordingly controls the operation of
the gate. Also an indicator light has been provided to alert
the motorists about the approaching train.
§
TRACK
SWITCHING
Using the same principle
as that for gate control, we have developed a concept of
automatic track switching. Considering a situation wherein an
express train and a local train are travelling in opposite
directions on the same track; the express train is allowed to
travel on the same track and the local train has to switch on
to the other track. Indicator lights have been provided to
avoid collisions .Here the switching operation is performed
using a stepper motor. In practical purposes this can be
achieved using electromagnets.
|
3. HARDWARE DESCRIPTION
The project
consists of three main parts:
Ø
8051
microcontroller
Ø
IR Transmitter
Ø
IR Receiver
Ø
Stepper Motor
Circuit
8051 CONTROLLER
The I/O ports of the 8051
are expanded by connecting it to an 8255 chip. The 8255 is
programmed as a simple I/O port for connection with devices
such as LEDs, stepper motors and sensors. More details of the
8255 are given later.
The following block
diagram shows the various devices connected to the different
ports of an 8255. The ports are each 8-bit and are named A, B
and C. The individual ports of the 8255 can be programmed to
be input or output, and can be changed dynamically. The
control register is programmed in simple I/O mode with port A,
port B and port C (upper) as output ports and port C (lower)
as an input port.
IR CIRCUITS
This circuit has two
stages: a transmitter unit and a receiver unit. The
transmitter unit consists of an infrared LED and its
associated circuitry.
§
IR
TRANSMITTER
The transmitter circuit
consists of the following components:
-
IC 555
-
Resistors
-
Capacitors
-
IR LED
The IR LED emitting
infrared light is put on in the transmitting unit. To generate
IR signal, 555 IC based astable multivibrator is used.
Infrared LED is driven through transistor BC 548.
IC 555 is used to
construct an astable multivibrator which has two quasi-stable
states. It generates a square wave of frequency 38kHz and
amplitude 5Volts. It is required to switch ‘ON’ the IR LED.
§
IR RECEIVER
The receiver circuit consists
of the following components:
-
TSOP1738
(sensor)
-
IC 555
-
Resistors
-
Capacitors
The receiver
unit consists of a sensor and its associated circuitry. In
receiver section, the first part is a sensor, which detects IR
pulses transmitted by IR-LED. Whenever a train crosses the
sensor, the output of IR sensor momentarily transits through a
low state. As a result the monostable is triggered and a short
pulse is applied to the port pin of the 8051 microcontroller.
On receiving a pulse from the sensor circuit, the controller
activates the circuitry required for closing and opening of
the gates and for track switching. The IR receiver circuit is
shown in the figure below.
STEPPER
MOTOR CIRCUIT
Here a stepper motor is
used for controlling the gates.
A
stepper motor is a widely used device that translates electrical
pulses into mechanical movement. They function as their name
suggests - they "step" a little bit at a time.
Steppers don't simply respond to a clock signal. They have several
windings which need to be energized in the correct sequence
before the motor's shaft will rotate. Reversing the order of
the sequence will cause the motor to rotate the other way.
Other Microcontroller projects
and articles
Digital
IC Tester using 8951 Microcontroller
Car
parking system using 8051 Microcontroller
Interfacing
an LCD to the 8051 Microcontroller
8051
microcontroller Instruction Set
8051
Microcontroller port programming
Programmable
number lock system
Water
level indicator cum controller
Robotic
car
Intelligent Train Engines
DC
Motor Controlling System using PIC
For more projects
click here
|
