Dynamic Wi-Fi Reconfigurable FPGA Based Platform for Intelligent Traffic Systems
Mihai Hulea, George Dan, Silviu Fole · InTech eBooks · 2011
Practical Applications and Solutions Using LabVIEW™ Software 378 programmable logic devices (PLDs), without a clearly defined distinction among them, they form the programmable Application-Specific Integrated Circuit (ASIC) group of devices (Smith, 1997).A FPGA is a device that consists of an array of basic logic cells that can be configured after fabrication using a certain programming technology.The logic cells are interconnected by wires and switch boxes with each other and with special input/output blocks (Mitra et al. 1998).Other important components include, but are not limited to multipliers, embedded block RAM and digital clock managers.The configurable logic blocks, or logic cells, are made up of two basic components: flip-flops and look-up tables (LUTs).The LUT is a storage block having the capacity of one bit that acts as a programmable gate.The input represents the address lines of the storing element and the output represents the value contained at this address.The input and output data can be synchronized with the clock signals.When programming the FPGA, one actually specifies the logic function of each basic logic cell and configures the connections represented by the switch boxes within the device.FPGA devices can be divided in two main classes: one time programmable FPGAs which are based on an antifuse approach and reconfigurable FPGAs which usually employ SRAM cells (Lyke, 2002).The SRAM cells contained in the device will not keep the stored information when the supply power is turned off and this way the configuration will be lost.Depending on its generation, the FPGA allows static or dynamic reconfiguration.In the case of static reconfiguration, the FPGA is programmed in the compiling phase and it cannot be reconfigured during operation, while in the second case, the FPGA can be reconfigured at any point in the lifetime of the application.Furthermore, dynamic reconfiguration can be total, when the entire device is reconfigured, or partial, when only a part of an operating FPGA is reconfigured.By using the hardware to its maximum capabilities and due to their truly parallel nature, FPGAs are able to assure better performance as compared to conventional processors (National Instruments 1 , 2011).They can be used in digital signal processing (DSP) systems where they can provide more complete solutions than the ones represented by traditional DSP implementations (programmable digital signal processors or ASICs) (Tessier & Burleson, 2001).Despite being slower than ASICs, the hardwired circuits realized by FPGAs have a speed advantage of several orders of magnitude over the software solutions on general purpose processors (Reis & Jess, 2004).Other applications which employ FPGA devices include space and defence systems (Tessier & Burleson, 2001;Altera, 2011), prototyping systems (Banovic, 2005), medical systems (Altera, 2010) and many other relatively new developed markets such as language recognition, bioinformatics (HPCWire, 2009), cryptography (Prasanna & Dandalis, 2007) etc.The capacity of reprogramming the hardware during operation allowed programmable logic to take over a central role in digital systems.The most important feature that results from the ability to reconfigure digital circuits is flexibility (Compton & Hauck, 2002).Among other things, it provides the possibility that a system might adapt to changing operating contexts or to unforeseen events (Lyke, 2002) in order to be able to fulfil its originally assigned tasks.Although this important feature, the flexibility of "on-field" reprogramming without going through re-fabrication with a new design (Xilinx, 2010), along with the FPGA based systems' low-cost and short time-to-market come at a considerable price, namely significant area overhead, increased delay and power consumption (Kuon et al., 2007), this did not affect their development and large scale usage.Systems that make use of user-reprogrammable logic elements such as FPGAs were studied (Patel & Moallem, 2010;Kalte, 2002) being well suited for applications with high www.intechopen.com