20-01-2011, 11:36 AM
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Title - Traffic Light Controller
1. Designed for Intersection of 4 Roads.
2. Timer ON/OFF selection for Night/Day time operation.
3. Variable pass timer for vehicles from 30sec - 60sec.
4. Low power consumption by utilizing LED for signal lamps.
5. Accurate timing, Compact, and low cost.
PROJECT CYCLE
1. Specification of the Project.
2. PCB Layout.
3. Device Test.
4. Code Implementation.
5. Program Test.
6. Pilot Run.
7. Documentation.
Description
Signal lamp consists of cluster of Red, Green, and Yellow LED’s. These lamps requires current of 60mA which microcontroller doesn’t capable to deliver this current, hence drivers are used.
The purpose of microcontroller is to switch on the signal lamps with proper timing and to read the timer on/off switch and to dip switches for pass time delay.
With the help of timer on/of switch the, Timer can be enabled or disabled. Led show the status of operation.
By configuring jumpers, the pass time delay can be changed.
In order to do all the activities a program (sequence of instruction) must be written for the microcontroller. This program is called firmware. In order to execute the program, Microcontroller requires basic configuration like 5V regulated power supply, clock, and reset circuit.
Microcontroller and IC’s requires 5V regulated power supply, which is obtained from 230V AC by using step down transformer , rectifier, filter and regulators.
ATMEL AT89S51 is used in the project. This particular microcontroller is chosen because following features.
1. 4K Bytes of In-System programmable flash memory.
2. Compatible with MCS®-51 Products
3. 4.0V to 5.5V Operating Range
4. Fully Static Operation: 0 Hz to 33 MHz
5. 128 x 8-bit Internal RAM
6. 32 Programmable I/O Lines
7. Low cost.
Software
1. KEIL Uv2 IDE
2. ATMEL PROGRAMMER.
Tools for schematic design
1. CAPTURE CIS (ORCAD)
Hardware
1. ATMEL 89C51 controller,
2. DRIVER BC557,
3. LED LAMPS,
4. DIP SWITCHES,
5. PCB for microcontroller unit, Reset switches, resistors etc,
6. Crystal 11.0592 MHz
7. 12 V POWER SUPPLY
Working Principle
Upon the power is applied to the system/circuit, microcontroller initializes its ports for driver, status led indicator, timer on/off switch, jumpers for variable pass time and enters in infinite loop where it checks for the timer on/off switch.
If it is enabled, timer is on and signal lamps switches in sequence. If timer is not enabled, all the roads are cleared. Every time it checks for the jumper to determine pass time for vehicles.
