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Overview of our project is to avoid congestion in traffic and to give priority to the emergency vehicle. Traffic control systems include signs, lights and other devices that communicate specific directions, warnings, or requirements. Traffic light controller (TLC) has been implemented using FPGA design which has many advantages over microcontroller some of these advantages are the speed, number of input/output ports and performance which are all very important in TLC design. Most of the TLCs implemented on FPGA are simple ones that have been implemented as examples of FSM. This paper concerned with an FPGA design implementation of a low cost 24-hour advanced traffic light controller system that was built as a term project of a VLSI design subject using verilog. The implemented traffic light is one of the real and complex traffic lights, for four roads and motorway with sensors and camera. The system has been successfully tested and implemented in hardware using Xilinx Spartan 3 FPGA.Using labview technique it can control the traffic properly.
Keywords: Field Programmable Gate Array, Traffic Light Controller, Very Large Scale Integration
The TLCs have limitations because it uses the pre-defined hardware, which is functioning according to the program that does not have the flexibility of modification on real time basis. Due to the fixed time intervals of green, orange and red signals the waiting time is more and vehicle uses more fuel. To make traffic light controlling more efficient, we exploit the emergence of new technique called as “Advanced Traffic Monitoring and Switching “. This makes the use of Sensor Networks along with Embedded Technology. The timings of Red, Green lights at each crossing of road will be intelligently decided based on the total traffic on all adjacent roads. Thus, optimization of traffic light switching increases road capacity and traffic flow, and can prevent traffic congestions.
This is a unique feature of this project which is very useful to emergency vehicle to reach the destination properly. The various performance evaluation criteria are average waiting time, switching frequency of green light at a junction and efficient emergency mode operation. The performance of the Advanced Traffic Light Controller is compared with the Fixed Mode Traffic Light Controller. It is observed that the proposed Advanced Traffic Light Controller is more efficient than the conventional controller in respect of less waiting time and efficient operation during emergency mode. Moreover, the designed system has simple architecture, fast response time, user friendliness and scope for further expansion.
I.FIELD-PROGRAMMABLE GATE ARRAY
A field programmable gate array (FPGA) is an integrated circuit (IC) that includes a two-dimensional array of general-purpose logic circuits, called cells or logic blocks, whose functions are programmable. The cells are linked to one another by programmable buses. A field-programmable gate array comprises any number of logic modules, an interconnect routing architecture and programmable elements that may be programmed to selectively interconnect the logic modules to one another and to define the functions of the logic modules. The basic device architecture of an FPGA consists of an array of configurable logic blocks (CLBs) embedded in a configurable interconnect structure and surrounded by configurable I/O blocks (IOBs). An IOB allows signals to be driven off-chip or optionally brought onto the FPGA onto interconnect segments. The IOB can typically perform other functions, such as tri-stating outputs and registering incoming or out-going signals. The configurable interconnect structure allows users to implement multi-level logic designs. In addition, FPGAs typically include other specialized blocks, such as block random access memories (BRAMs) and digital signal processors (DSPs). These specialized blocks perform more specific tasks than the CLBs, but can still be configured in accordance with a variety of options to enable flexible operation of the FPGA. Field programmable gate arrays may be classified in one of two categories. One category of FPGA devices is one-time programmable and uses elements such as antifuses for making programmable connections. The other category of FPGA devices is reprogrammable and uses devices such as transistor switches as the programmable elements to make non-permanent programmable connections. An FPGA can support hundreds of thousands of gates of logic operating at system speeds of tens of megahertz. To implement a particular circuit function, the circuit is mapped into the array and the appropriate programmable elements are programmed to implement the necessary wiring connections that form the user circuit. The FPGA is programmed by loading programming data into the memory cells controlling the configurable logic blocks, I/O blocks, and interconnect structure.
A field-programmable gate array (FPGA) is an integrated circuit designed to be configured by the customer or designer after manufacturingââ‚¬”hence “field-programmable”. The FPGA configuration is generally specified using a hardware description language (HDL), similar to that used for an application-specific integrated circuit (ASIC) (circuit diagrams were previously used to specify the configuration, as they were for ASICs, but this is increasingly rare). FPGAs can be used to implement any logical function that an ASIC could perform. The ability to update the functionality after shipping, and the low non-recurring engineering costs relative to an ASIC design (not withstanding the generally higher unit cost), offer advantages for many applications.
FPGAs contain programmable logic components called “logic blocks”, and a hierarchy of reconfigurable interconnects that allow the blocks to be “wired together”ââ‚¬”somewhat like a one-chip programmable breadboard. Logic blocks can be configured to perform complex combinational functions, or merely simple logic gates like AND and XOR. In most FPGAs, the logic blocks also include memory elements, which may be simple flip-flops or more complete blocks of memory.
Historically, FPGAs have been slower, less energy efficient and generally achieved less functionality than their fixed ASIC counterparts. A combination of volume, fabrication improvements, research and development, and the I/O capabilities of new supercomputers have largely closed the performance gap between ASICs and FPGAs.
Advantages include a shorter time to market, ability to re-program in the field to fix bugs, and lower non-recurring engineering costs. Vendors can also take a middle road by developing their hardware on ordinary FPGAs, but manufacture their final version so it can no longer be modified after the design has been committed.
Xilinx claims that several market and technology dynamics are changing the ASIC/FPGA paradigm:
IC costs are rising aggressively
ASIC complexity has bolstered development time and costs
R&D resources and headcount is decreasing
Revenue losses for slow time-to-market are increasing
Financial constraints in a poor economy are driving low-cost technologies.
These trends make FPGAs a better alternative than ASICs for a growing number of higher-volume applications than they have been historically used for, to which the company attributes the growing number of FPGA design starts. Some FPGAs have the capability of partial re-configuration that lets one portion of the device be re-programmed while other portions continue running.
B.FPGA Versus CPLDs:
The primary differences between CPLDs and FPGAs are architectural. A CPLD has a somewhat restrictive structure consisting of one or more programmable sum-of-products logic arrays feeding a relatively small number of clocked registers. The result of this is less flexibility, with the advantage of more predictable timing delays and a higher logic-to-interconnect ratio. The FPGA architectures, on the other hand, are dominated by interconnect. This makes them far more flexible (in terms of the range of designs that are practical for implementation within them) but also far more complex to design for.
Another notable difference between CPLDs and FPGAs is the presence in most FPGAs of higher-level embedded functions (such as adders and multipliers) and embedded memories, as well as to have logic blocks implement decoders or mathematical functions.
C. Security considerations:
With respect to security, FPGAs have both advantages and disadvantages as compared to ASICs or secure microprocessors. FPGAs’ flexibility makes malicious modifications during fabrication a lower risk. For many FPGAs, the loaded design is exposed while it is loaded (typically on every power-on). To address this issue, some FPGAs support bit stream encryption.
D.Applications of FPGAs:
FPGAs have gained rapid acceptance and growth over the past decade because they can be
applied to a very wide range of applications. A list of typical applications includes: random logic,integrating multiple SPLDs, device controllers, communication encoding and filtering, small to medium sized systems with SRAM blocks, and many more.
Other interesting applications of FPGAs are prototyping of designs later to be implemented in
gate arrays, and also emulation of entire large hardware systems.
II.RADIO FREQUENCY COMMUNICATION:
RF itself has become synonymous with wireless and high-frequency signals, describing anything from AM radio between 535 kHz and 1605 kHz to computer local area networks (LANs) at 2.4 GHz. However, RF has traditionally defined frequencies from a few kHz to roughly 1 GHz. If one considers microwave frequencies as RF, this range extends to 300 GHz. A wave or sinusoid can be completely described by either its frequency or its wavelength. They are inversely proportional to each other and related to the speed of light through a particular medium. As frequency increases, wavelength decreases. For reference, a 1 GHz wave has a wavelength of roughly 1 foot, and a 100 MHz wave has a wavelength of roughly 10 feet.
A Passive Infra Red sensor (PIR sensor) is an electronic device that measures infrared (IR) light radiating from objects in its field of view. PIR sensors are often used in the construction of PIR-based motion detectors. Apparent motion is detected when an infrared source with one temperature, such as a human, passes in front of an infrared source with another temperature, such as a wall.
All objects emit what is known as black body radiation. It is usually infrared radiation that is invisible to the human eye but can be detected by electronic devices designed for such a purpose. The term passive in this instance means that the PIR device does not emit an infrared beam but merely passively accepts incoming infrared radiation.
These sensors are used as the road traffic detectors which is used for the detection of the presence (traffic) of vehicles at precisely determined measuring points, are an extremely important element of the urban traffic control system. The intelligent road consists of IR sensors to detect and transferring the data to the server in real time. The detectors are installed along the road in order to ensure the scanning of traffic stream and to transmit its
Parameters at proper time i.e. stream velocity, its intensity and quantity of transport
Means. The transport means may be subdivided into categories e.g. motor cars, small
and big trucks and long vehicles.
The essential functions of road traffic detectors are:
ââ‚¬” Optimization of traffic lights control for the road crossings and pedestrians
ââ‚¬” Creation of traffic database and road traffic changes monitoring in order to implement
proper control and management modifications,
-Data acquisition at locations for which early detection of traffic disturbances.
As the name implies, it is a system in which the circuit is closed and all the elements are directly connected. This is unlike broadcast television where any receiver that is correctly tuned can pick up the signal from the airwaves. Directly connected in this context includes systems linked by microwave, infrared beams, etc. This article introduces the main components that can go to make up CCTV systems of varying complexity.
Many cities and motorway networks have extensive traffic-monitoring systems, using closed-circuit television to detect congestion and notice accidents
V. RF TRANSRECEIVER:
This transceiver has a transmit side (Tx) and a receive side (Rx), which are connected to the antenna through a duplexer that can be realized as a switch or a filter, depending on the communications standard being followed. The input preselection filter takes the broad spectrum of signals coming from the antenna and removes the signals not in the band of interest. This may be required to prevent overloading of the low-noise amplifier (LNA) by out-of band signals.
The LNA amplifies the input signal without adding much noise. The input signal can be very weak, so the first thing to do is strengthen the signal without corrupting it. As a result, noise added in later stages will be of less importance. The image filter that follows the LNA removes out-of-band signals and noise before the signal enters the mixer. The mixer translates the input RF signal down to the
intermediate frequency, since filtering, as well as circuit design, becomes much easier at lower frequencies for a multitude of reasons. The other input to the mixer is the local oscillator (LO) signal provided by a voltage-controlled oscillator inside a frequency synthesizer. The desired output of the mixer will be the difference between the LO frequency and the RF frequency.
At the input of the radio there may be many different channels or frequency bands. The LO frequency is adjusted so that the desired RF channel or frequency band is mixed down to the same intermediate frequency (IF) in all cases. The IF stage then provides channel filtering at this one frequency to remove the unwanted channels. The IF stage provides further amplification and automatic gain control (AGC) to bring the signal to a specific amplitude level before the signal is passed on to the back end of the receiver. It will ultimately be converted into bits (most modern communications systems use digital modulation schemes) that could represent, for example, voice, video, or data through the use of an analog-to-digital converter.
On the transmit side, the back-end digital signal is used to modulate the carrier in the IF stage. In the IF stage, there may be some filtering to remove unwanted signals generated by the baseband, and the signal may or may not be converted into an analog waveform before it is modulated onto the IF carrier. A mixer converts the modulated signal and IF carrier up to the desired RF frequency. A frequency synthesizer provides the other mixer input. Since the RF carrier and associated modulated data may have to be transmitted over large distances through lossy media (e.g., air, cable, and fiber), a power amplifier (PA) must be used to increase the signal power. Typically, the power level is increased from the milliwatt range to a level in the range of hundreds of milliwatts to watts, depending on the particular application. A lowpass filter after the PA removes any harmonics produced by the PA to prevent them from also being transmitted.
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