Hackster's FPGAdventures: The Mi-V Ecosystem and the Future of Microchip's PolarFire SoC

Launched in 2020, Microchip's PolarFire SoC Icicle Kit marked a bold new step for the company: a device, priced to be accessible to professional designers and the maker community alike, which combined its in-house field-programmable gate array (FPGA) technology with SiFive's processor cores built around the free and open source RISC-V architecture.

"Our goal in bringing out FPGA SoCs was to be able to take advantage of an impending revolution in the compute segment using an open ISA," Microchip's Shakeel Peera explains. "It allowed us to innovate around power efficiency and cybersecurity using a democratized development process that would challenge the established order of FPGA SoC offerings currently available. We took a stand in smashing the established business processes in favor of democratization."

The story so far

To see just where that stand has taken the company, we set off on our FPGAdventure — starting with investigating just what the PolarFire SoC Icicle Kit is. Effectively a chunky single-board computer, our first steps put the hardware through its paces — and came across a few pain points that, to its credit, Microchip was quick to address.

Installing the bundled development software, Libero SoC, was next on the to-do list, a process which proved rather more painful than it should have been — in no small part because it takes a long time to change the direction of a ship as big as Microchip, and the company has been working with proprietary technology and large corporations for decades. Its desire to attract makers is more recent, at least at the level of its FPGA devices, and its software lacks a little in user-friendliness as a result — though few could deny its capabilities.

As we began experimenting with Libero SoC those capabilities became clear, but so too did the complexity of the software. Microchip has published a range of tutorials, while SmartDesigner tries to make defining your own hardware as easy as drag-and-drop — but remnants of its merger with MicroSemi remain in the form of outdated guides, dead links, and the like, which Microchip is actively working to resolve and refresh.

Digging deeper into the Linux-on-RISC-V side of the PolarFire SoC Icicle Kit, we found evidence that Microchip does indeed listen: in just four months since our first unboxing the sample Linux distribution had been updated to resolve every single one of the issues we ran into — from the second Ethernet port failing to work to an extreme bare-bones package list, which made working on-device far harder than it should have been. By contrast, installing the latest Linux build provided a much more welcoming experience — including handy open source examples for using various board features.

Our next step was, of course, to dig into those samples directly. With Microchip providing the source code as a jumping-off point, the code samples act as a first stop for developers looking to build Linux software to run on both the Icicle Kit and the broader PolarFire SoC ecosystem — about which more later. There are samples for everything from random number generation to communication between the RISC-V cores and the FPGA — and while they're not always well-commented, they are at least fairly easy to follow.

The next leg of our journey was to focus on a particularly interesting feature of the PolarFire SoC: Asymmetric Multiprocessing, or AMP. In this, the four application cores on the PolarFire SoC are split in two — creating, in effect, two distinct systems that can nevertheless share resources. Using this, it's possible to run Linux alongside a real-time operating system (RTOS) or bare-metal application — or any other combination, excluding running two copies of Linux side-by-side.

For the penultimate step on the FPGAdventures journey, we returned to Libero SoC — this time to use its SmartDesigner to actually define a simple logic circuit, an AND gate, and flash it to the FPGA. It's here the power and flexibility of the PolarFire SoC became clear: the ability to use the RISC-V cores for an operating system or bare-metal application while redefining the FPGA resources in any way you see fit. There's a learning curve, and one which Microchip could arguably do more to ease, but rewards await those willing to put in the effort.

And with that, our journey ends here — with a look at what's happening with the PolarFire SoC in the broader community, which includes a rather exciting partnership with NASA to take the technology to the stars.

Mi-V, your-V

The PolarFire SoC is part of what Microchip calls the "Mi-V" (pronounced "My-Five," like RISC-V is pronounced "Risk-Five") ecosystem, which boasts an impressive and growing number of partner companies and projects — from Open Robotics' Robot Operating System (ROS) to Microsoft's Azure, GNOME, Antmicro, Imperas, Trenz Electronic, Zephyr, and of course SiFive, the company that provides the CPU IP used in the PolarFire SoC.

Some of these partners, like Ashling, MathWorks, and AdaCore, provide design tools compatible with the PolarFire SoC; others, like Amazon FreeRTOS, Linux, and seL4 provide operating systems or kernels; still others, like Antmicro, Aries Embedded, Trenz Electronic, and Emdala Technologies provide design services. A few are taking the PolarFire SoC at the heart of the Icicle Kit and building their own devices too — each tailored to particular use-cases.

Aries Embedded, for one example, has its own PolarFire-based system-on-module (SOM) dubbed the M100PFS. "The platform integrates a hardened real-time, Linux capable, RISC-V-based MPU subsystem on the mid-range PolarFire FPGA family," the company explains, "bringing low power consumption, thermal efficiency and defense grade security to embedded systems."

Aldec's TySOM-M, meanwhile, is a fully-featured alternative to the Icicle Kit in a smaller form factor. "Our TySOM-M debut board inherits all the features and benefits of the PolarFire SoC FPGA," claims Aldec's Zibi Zalewski. "These, combined with the board’s own features and benefits, provide engineers with a highly versatile platform for developing applications that will cost less than if they were to target Arm cores."

Smaller still is the PolarBerry, a system-on-module that designer Sundance DSP claims is "designed to be application-flexible while also being quick to use and deploy. Its combination of features make it perfect for applications that require high-performance but a low power draw, defense-level security, a real-time, deterministic RISC-V processor that’s capable of Linux, a small physical profile, immediate connectivity, or custom extensibility — such as those in the autonomous vehicle or defense industries."

The PolarFire SoC is even found in open source projects like Ali Uzel's SAVVY-V, a bold attempt at creating a stackable single-board computer design for cluster projects — though one, which is now two years overdue, having originally been scheduled to launch by the end of 2020.

The future of PolarFire

What exists in the ecosystem now, though, provides only a hint of things to come. Microchip itself is pushing the PolarFire SoC technology to new sectors, beginning with its recently-announced Smart Embedded Vision development platform — designed to communicate with two 4K-resolution cameras over MIPI CSI-2 ports and with an HDMI video output lacking in the Icicle Kit's design.

But the company has higher goals than that — literally. Back in September NASA announced it had partnered with Microchip and SiFive to use the companies' technologies, proven in the PolarFire SoC, as part of a project to create a new processor for future space missions: the High-Performance Spaceflight Computing (HPSC) chip, a replacement for the BAE Systems RAD750 launched in 2001 and built on IBM's PowerPC 750 technology from 1997.

"We are making a joint investment with NASA on a new trusted and transformative compute platform. It will deliver comprehensive Ethernet networking, advanced artificial intelligence/machine learning processing and connectivity support while offering unprecedented performance gain, fault-tolerance, and security architecture at low power consumption," says Microchip's Babk Samimi of the project.

"We will foster an industry wide ecosystem of single board computer partners anchored on the HPSC processor and Microchip's complementary space-qualified total system solutions to benefit a new generation of mission-critical edge compute designs optimized for size, weight, and power."

The company is quieter, however, on its hopes for the PolarFire SoC in the maker market — and, to be fair, going to the moon is a reasonable thing to distract one's attention. When we set off on our FPGAdventure nearly a year ago, the company was keen to see how its platform would appeal to the maker masses — and, entirely to its credit, our highlighting of various pain-points along the way has been accepted.

But while many of the stumbling blocks we encountered on our journey have been addressed, others have not — and in the case of issues like having to run your own licensing server to even load Libero SoC, the lack of truly beginner-friendly documentation for the software, or even the absence of alternative and more accessible tooling, there's a lot of work to be done.

None of which should put people off investigating the platform for themselves: while not quite priced at impulse-purchase levels the PolarFire SoC is affordable enough for those who have been thinking of dipping their toes into the RISC-V and FPGA waters, and for all that you'll need to put in the hours to get your head around Libero SoC, it's an undeniably powerful tool with a license bundled with every board purchased — albeit one you'll need to renew, for free, on an annual basis.

Whether you're taking the plunge or not, one thing is clear: Microchip's PolarFire SoC platform is a technology to watch.

More information on the PolarFire SoC Icicle Kit is available on the Microchip website and can be found on Avnet's product page as well.

Read the whole series:

• FPGAdventures Series #1: Unboxing the PolarFire SoC Icicle
• FPGAdventures Series #2: Installing Microchip's Libero SoC
• FPGAdventures Series #3: First Steps with Libero SoC
• FPGAdventures Series #4: Linux on RISC-V
• FPGAdventures Series #5: Linux Code Samples
• FPGAdventures Series #6: Asymmetric Multiprocessing (AMP)
• FPGAdventures Series #7: Building Logic using Libero SoC