Advantages of FPGA-Based Multiprocessor Systems in Industrial ...

This paper argues and shows that FPGAs can at leastrelieve some of the design problems discussed above. To thisend, Section II briefly surveys the possibilities andadvantages of those FPGAs. A short introduction to thesimple and easy use of soft-core processors will be given.As Section III describes, FPGAs today have grown in sizesuch that they can even realize one or even several custommadeprocessor cores.In order to show the potential benefits, Section IVdescribes an industrial case study in the area of cutting-edgeoffset printing. Since the entire system has been grownduring several years, it exhibits some limitations, which alsohinder future developments. In order to expand to newfrontiers, this section also proposes a new architecture, whichis based on a multiprocessor platform.Section V reports on a prototypical implementation, whichcan be seen as a proof-of-concept. The section also discussesthe required resource consumption as well as other technicaldetails. Finally Section V and VI finish this paper with acritical discussion and the conclusion respectively.II. BACKGROUND ON FPGASFirst commercial FPGA’s were released by XILINX in themiddle of the 80’s of the last century. At those times, deviceswere small, slow, and quite expensive. The first XILINXdevice XC2064 had 1200 gates. Today, FPGA’s offermillions of system gates and operate at a speed of up to300 MHz. Since the price of currently available FPGAs startsbelow 10 US$, many manufactures use them even for endproducts, such as mobile phones, network solutions, andmultimedia devices.Even factory automation applications might profit from thegood performance-to-cost 2 ratio of modern FPGAs. Here,FPGAs are of particular interest, because a small number ofproduction systems require significant development efforts.Using FPGAs in the design process has the following threedistict advantages. First, most FPGA-vendors support thedesign and development process by providing powerful andeasy-to-use electronic design tools (EDA), excellentdocumentation, and personal support. Second, demonstrationexamples do not involve high manufacturing costs as wouldbe usual with ASICs. Third, modifications and adjustmentscan be implemented at any stage of the design process andeven “in the field”. Advanced systems extent the latter pointeven further in that they allow the dynamic reconfigurationof the running hardware. Such systems are subject of currentresearch efforts, also known as dynamically reconfigurablehardware [10]. This approach receives recent attention,because it allows for multiply re-using valuable resources.FPGAs have grown in size that much that they allow forthe soft-implementation of processor cores, which might alsobe a DSP-core. Thus, a design challenge is to decide, which2 In this context, “cost” refers not only to the actual FPGA but also torequired tools, design efforts, maintenance, etc.parts of the system, i.e., functionalities, are to beimplemented directly in hardware gates or processed bysoftware, which runs inside the FPGAs soft core. State-ofthe-artEDA-tools, such as ALTERA's system-on-aprogrammable-chip(SOPC) Builder and XILINX’Embedded Development Kit (EDK), simplify this parallelhardware-software co-design process dramatically. This isaccomplished by automatically recognizing all hardwarecomponents and providing software access methods forthem. Also, the development tools solve the address andresource management automatically on the fly (see alsoSection IV.C).Furthermore, the developer can resort to many ready-tousecomponents, also called intellectual properties (IP), suchas network-Interfaces, video controllers, memory controllers,and so forth. The usage of IP-cores reduces the developmentefforts and thus may help reduce costs.III. SOFT-CORES AND MULTIPROCESSOR SYSTEMSAs mentioned above, FPGAs offer the possibility ofincorporating soft-cores. Soft-core processors can beconsidered as equivalents to a microcontroller or “computeron a chip”. They combine a CPU, peripherals, and memoryon a single chip. They also provide access beyond the actualFPGA chip through integrated standard or custom-madeinterfaces. Some available reduced instruction set computer(RISC) architectures are [3, 4, 5]:1. NIOS and NIOS II CPUs from ALTERA ,2. LEON2 and LEON3 CPUs from Gaisler Research,3. and the Microblaze CPU from XILINX.Some of the currently available FPGAs allow for therealization of several processors simultaneously. As is wellknown, multiprocessor systems are a proper method toincrease system performance and to concentrate processingelements in one FPGA. Since multiprocessor systems aresupported by the EDA tools, the system generation can becompleted within a couple of days. Generally, most vendorssupport multiprocessor systems by providing dedicatedhardware constructs, such as mutexes, to synchronizedaccesses to shared resources. For a general introduction tomultiprocessor systems, the interested reader is referred tothe pertinent literature [7].IV. INDUSTRIAL CASE STUDYThis section presents an industrial case study. Thisincludes a description of the existing system, the discussionof the problems and goals, and the presentation of aprototypical implementation.A. The Existing SystemIn 1993, basysPrint Ltd. introduced a technology calledComputer To conventional Plate (CTcP) for the exposure