25-08-2017, 09:32 PM
4 Way Traffic Signal
[attachment=42870]
Abstract
The project aims to design a Traffic Light Controller using VHDL and implement the Traffic Light Controller in FPGA. The traffic in road crossings/junctions are controlled by switching ON/OFF Red, Green & Amber lights in a particular sequence. The Traffic Light Controller is designed to generate a sequence of digital data called switching sequences that can be used to control the traffic lights of a junction in a fixed sequence using VHDL.
Introduction
Traditionally traffic lights are controlled by microcontroller 89C51. The primitive mechanical traffic lights have no way of having a versatile delay. But using CPLD as a 16-bit μP and use it in the domestic application to improve the primitive mechanical traffic lights.This project attempts control the traffic lights using VHDL.
It is often useful to be able to sequence through an arbitrary number of states,staying in each state an arbitrary amount of time. For example, consider the set of traffic lights shown in Figure 8.13. The lights are assumed to be at a four-way intersection with one street going north-south and the other road going east-west.
Being an electronic system it is reliable, compact and maintenance free. VHDL makes the system versatile as the on off times can be easily varied by changing the delay loops through software. Even the sequence of lights i.e. whether the yellow light has to glow or not can be programmed easily by modifying the software. This project is practically implemented and tested. Because Programmable Integrated Circuits provides repeatability and flexibility, we can program it more than 10,000 times. And this is not possible is fixed logic IC’s. The best part of using CPLD is we can easily reprogram it. We do not have need to remove the CPLD from the hardware we can program it by placing it into the same board.
CPLD XC9572
In the world of digital electronic systems, there are three basic kinds of devices: memory microprocessors, and logic devices. Memory devices store random information such as the contents of a spreadsheet or database. Microprocessors execute software instructions to perform a wide variety of tasks such as running a word processing program or video game. Logic devices provide specific functions, including device-todevice interfacing, data communication, signal processing, data display, timing and control operations, and almost every other function a system must perform.
Delays in Traffic
The delay is defined by the amount of additional time a vehicle takes to complete its journey through the network because of traffic lights. Another interesting metric is the throughput which gives the number of vehicles that cross the intersection in a specified amount of time. One of the solutions to this problem would be to design controllers that use adaptive policies. Such adaptive systems could react to current perceptions of traffic conditions and select the best actions in order to optimize the traffic flow at the intersection. Moreover, these adaptive systems could even be equipped with communication networks that could enable adaptive coordination between different intersections in order to improve the traffic flow globally. Such coordination could help minimize the overall delay caused by traffic signals.
Working
Traffic lights operate with the rising edge of the clock. This is generated by using the 555 timer (Astable Multivibrator).The Programming is done in VHDL language. Its working is similar to Normal traffic lights. But single CPLD chip can be used to control the traffic of number of road signals. Because it has large number of input and output pins . in its working +5V is given to the CPLD and as it receive the rising edge of clock, and it starts its sequence of traffic lights We can increase or decrease the delay between the transition of signals according to the requirement.
[attachment=42870]
Abstract
The project aims to design a Traffic Light Controller using VHDL and implement the Traffic Light Controller in FPGA. The traffic in road crossings/junctions are controlled by switching ON/OFF Red, Green & Amber lights in a particular sequence. The Traffic Light Controller is designed to generate a sequence of digital data called switching sequences that can be used to control the traffic lights of a junction in a fixed sequence using VHDL.
Introduction
Traditionally traffic lights are controlled by microcontroller 89C51. The primitive mechanical traffic lights have no way of having a versatile delay. But using CPLD as a 16-bit μP and use it in the domestic application to improve the primitive mechanical traffic lights.This project attempts control the traffic lights using VHDL.
It is often useful to be able to sequence through an arbitrary number of states,staying in each state an arbitrary amount of time. For example, consider the set of traffic lights shown in Figure 8.13. The lights are assumed to be at a four-way intersection with one street going north-south and the other road going east-west.
Being an electronic system it is reliable, compact and maintenance free. VHDL makes the system versatile as the on off times can be easily varied by changing the delay loops through software. Even the sequence of lights i.e. whether the yellow light has to glow or not can be programmed easily by modifying the software. This project is practically implemented and tested. Because Programmable Integrated Circuits provides repeatability and flexibility, we can program it more than 10,000 times. And this is not possible is fixed logic IC’s. The best part of using CPLD is we can easily reprogram it. We do not have need to remove the CPLD from the hardware we can program it by placing it into the same board.
CPLD XC9572
In the world of digital electronic systems, there are three basic kinds of devices: memory microprocessors, and logic devices. Memory devices store random information such as the contents of a spreadsheet or database. Microprocessors execute software instructions to perform a wide variety of tasks such as running a word processing program or video game. Logic devices provide specific functions, including device-todevice interfacing, data communication, signal processing, data display, timing and control operations, and almost every other function a system must perform.
Delays in Traffic
The delay is defined by the amount of additional time a vehicle takes to complete its journey through the network because of traffic lights. Another interesting metric is the throughput which gives the number of vehicles that cross the intersection in a specified amount of time. One of the solutions to this problem would be to design controllers that use adaptive policies. Such adaptive systems could react to current perceptions of traffic conditions and select the best actions in order to optimize the traffic flow at the intersection. Moreover, these adaptive systems could even be equipped with communication networks that could enable adaptive coordination between different intersections in order to improve the traffic flow globally. Such coordination could help minimize the overall delay caused by traffic signals.
Working
Traffic lights operate with the rising edge of the clock. This is generated by using the 555 timer (Astable Multivibrator).The Programming is done in VHDL language. Its working is similar to Normal traffic lights. But single CPLD chip can be used to control the traffic of number of road signals. Because it has large number of input and output pins . in its working +5V is given to the CPLD and as it receive the rising edge of clock, and it starts its sequence of traffic lights We can increase or decrease the delay between the transition of signals according to the requirement.
![[Image: Traffic-Light-Circuit.gif]](http://circuitdigest.com/sites/default/files/circuitdiagram/Traffic-Light-Circuit.gif)