S2C opens up FPGA prototyping for PCIe fabrics

Reconfigurable computing began with FPGA cards dropped into expansion slots in workstations. FPGA-based prototyping vendors tended away from that model as interconnect speeds rose and cabling complexity between modules increased. Much faster PCIe interfacing and bigger FPGAs mean revisiting the concept.

FPGA vendors and their ecosystem partners routinely deliver development boards in PCIe edge connector form factors. It’s a plus for not only facilitating easy host connectivity, but in many cases the end design targets a PCIe interface. IP for PCIe interfacing is now commonly available – for instance, Xilinx offers its own PCIe 2.1 solution for Endpoint and Root Port applications, and PLDA offers their XpressRICH3 soft IP for PCIe 3.0 with even more advanced configurability.

State-of-the-art FPGAs also make a PCIe edge card attractive. Anyone who has ever run into the woes of sorting out benchtop power supply specifications and cabling just to get a development board to power up for the first time knows how valuable having a qualified solution is. Power sequencing for advanced FPGAs is trickier than first glance indicates; some PCIe FPGA development boards have configurable power modules to account for various requirements. Server-class power supplies are more than up to the task of supplying enough power to PCIe expansion slots, allowing a card with a Xilinx UltraScale VU440 FPGA to drop in and run immediately. Not having to worry about power for prototypes can shave days off getting started in actual development.

Combining those two ideas opens up creative system configurations. For example, PCIe can be deployed as a high-speed fabric interconnect between FPGA boards and other PCIe-enabled systems. This is a common configuration in AdvancedTCA, VPX (VITA 46.4), and other systems where the PCIe fabric runs down a backplane. An FPGA-based prototyping card, or several of them in a PCIe edge card passive backplane system, could easily hook into such a fabric. One could actually use Ethernet ports for the host interface including FPGA download and debug and leave the PCIe fabric completely open for application traffic.

I’m positive it was that type of fabric-centric thinking that prompted a customer to request S2C to develop a PCIe-based version of their VU440 Prodigy Logic Module (LM), just announced. The new FPGA-based prototyping board can be used standalone in a single Xilinx UltraScale VU440 configuration with the Prodigy Player Pro software suite. One interesting new feature is an onboard microSD card enabling the FPGA to be re-downloaded from up to four design files. The LM also accommodates the Prodigy Daughter Card family for I/O expansion with either off-the-shelf modules from S2C or customer-designed modules.

Download and debug of the PCIe VU440 Prodigy Logic Module is possible over Ethernet or USB, and an Ethernet network can quickly connect and manage multiple LMs. This makes the PCIe passive backplane configuration attractive, opening up scalability for large configurations without exotic cabling requirements. LMs could also be distributed across several different enclosures or racks since PCIe cables are readily available in lengths of a few meters without sacrificing speed.

Reconfigurability is no longer restricted to a slot within a host in this concept. FPGA-based prototypes can mix and match with finished PCIe-based hardware. A rather large design can be placed in a single Xilinx VU440, but the more interesting part of this for me is the PCIe fabric capability – integrated with the S2C Prodigy Complete Prototyping Platform.

For more on the S2C announcement:

S2C’s PCIe Virtex UltraScale Solution Provides Advantages Beyond Traditional FPGA Prototyping

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