Xcell Journal Issue 78: Charge to Market with Xilinx 7 Series ...

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XCELLENCE IN PROTOTYPING Lowering the Barriers to a Successful FPGA-Based Prototype Project The Xilinx Virtex-6 and Synopsys HAPS systems make prototyping practical for ASIC designs. by Troy Scott Senior Product Marketing Manager Synopsys troy.scott@synopsys.com 32 Xcell Journal First Quarter 2012
Recent surveys of the ASIC designer community show that more than 70 percent of all design projects use some form of FPGA-based prototype to provide a high-speed model of the design prior to the tapeout of a test chip. The prototype helps to start software development tasks and to close functional coverage earlier in the design cycle. In many organizations, the versatility and reuse benefits of a commercially available FPGA-based prototyping system have led to a much improved return on investment compared with custom circuit boards developed in-house. The Synopsys HAPS High-Performance ASIC Prototyping System has a long pedigree of using Xilinx ® Virtex ® FPGAs as a logic host for ASIC prototyping. Starting in 1987 at HARDI Electronics AB of Lund, Sweden (now part of the Hardware Platform Group at Synopsys), the HAPS system of circuit boards has proven to be a versatile tool for thousands of prototyping projects. To understand why, it’s instructive to take a deeper look at the functional elements of the Virtex-6 and the HAPS system architecture that have made this combination a state-of-the-art solution. VIRTEX-6 IS IDEAL FOR ASIC PROTOTYPING Throughout its history the HAPS prototyping systems have leveraged the Virtex family of devices, including the Virtex-II, Virtex-II Pro, Virtex-4, Virtex- 5 and, most recently, Virtex-6 LX760 devices. The highest-capacity LX760 has proven its utility as a vehicle for ASIC prototyping for many companies. Designers can apply both the programmable and embedded-block functions of the device to the prototyping effort. The primary LX760 logic building block, a slice, is composed of programmable lookup tables (LUTs) and storage elements used to implement combinatorial functions, along with small RAM blocks or shift registers. A total of 118,560 slices are available in the LX760, providing a deep resource to host logic functions such as parity, XOR, AND, OR and synchronous logic of the original ASIC RTL. When considering the migration of arithmetic functions such as multipliers, accumulators and other DSP logic, the LX760 provides embedded signal-processing blocks that are far more area-efficient than slice-based logic cells. An LX760 provides 864 DSP blocks along with the DSP48E1 slice, consisting of a 25 x 18-bit two’s complement multiplier and 48-bit accumulator. The Synopsys Synplify Premier FPGA logic-synthesis tool automatically targets these essential building blocks and provides the best clock performance. System-on-chip (SoC) designs include various memories provided by either the target ASIC fab’s memory library or a memory compiler. In most cases FPGAs can represent these memories efficiently using slices for smaller register files, embedded block RAM for wider, deeper arrays or, for the largest memories, HAPS memory daughterboards as a host. Effective ASIC memory migration is part of the FPGA-based prototyping methodology, which often involves assigning an alternative FPGA-friendly implementation to ensure the most efficient use of onchip RAM. Substitutions—driven, for example, by Verilog HDL ‘define—help provide an easy way to switch between modules as the code is targeted to different implementations. In many cases ASIC memory compilers can generate an “emulation-friendly” light version of the model that excludes test logic so that the prototyping can more easily migrate to the prototype system. A Virtex-6 760LX provides up to 8,280 kbits of distributed slice-based RAM and 25,920 kbits of block RAM for hosting memory modules. XCELLENCE IN PROTOTYPING The Virtex-6 family provides up to nine embedded PLL-based mixed-mode clock managers (MMCMs) that can serve as frequency synthesizers for a wide range of frequencies, as a jitter filter for either external or internal clocks, and as deskew clocks. The Virtex-6 MCMM is capable of output frequencies from 4.69 MHz to 800 MHz. This is a key resource for the prototype Designers can apply the programmable and embedded-block functions of the LX760 to the ASIC prototyping effort. to achieve multimegahertz speeds of internal clocks. The Synopsys Certify multi-FPGA prototyping environment eases the implementation of ASIC clocks by targeting both onboard PLLs of the HAPS system and the embedded LX760 MMCMs with clock-distribution IP that’s generated based on how a design is partitioned. HAPS’ MODULAR ARCHITECTURE APPLIED The HAPS design team applied some key design criteria to balance the cost, performance and connectivity needs of a prototyping circuit board. For hardware-assisted verification tools such as an ASIC emulator, RTL debugging and verification was the primary application. But the prototype community was more concerned with “validation,” a process in which testing scenarios are vastly expanded. This required that the prototype performance be high enough to interface to real-world protocols like Gigabit Ethernet and double-datarate (DDR) memory interfaces, and execute SoC processors to boot an operating system. These implications convinced the hardware designers to provide a very open, modular architecture that maximized FPGA I/O access, along with a reconfigurable interconnect scheme First Quarter 2012 Xcell Journal 33
Page 1 and 2: Xcell ISSUE 78, FIRST QUARTER 2012
Page 3 and 4: Add it up: 10 GbE, 40 GbE, and 100G
Page 6 and 7: C O N T E N T S VIEWPOINTS XCELLENC
Page 8 and 9: COVER STORY Charge to Market with X
Page 10 and 11: COVER STORY CUSTOMER INNOVATION hav
Page 12 and 13: COVER STORY The ROHS-compliant Kint
Page 14 and 15: XPERT OPINION Embedded Vision: FPGA
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Page 18 and 19: XPERT OPINION Figure 3 - Pedestrian
Page 20 and 21: XCELLENCE IN AUTOMOTIVE APPLICATION
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Page 36 and 37: XPLANATION: FPGA 101 Ins and Outs o
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Page 42 and 43: XPLANATION: FPGA 101 Using FPGAs to
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Page 48 and 49: XPLANATION: FPGA 101 Tips and Trick
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Page 52 and 53: ASK FAE-X How to Build a Self-Check
Page 54 and 55: ASK FAE-X Disk File Stimulus Script
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