Common readers of our FPGAdventures collection will probably be conversant in Microchip’s PolarFire SoC Icicle Package and Video Package growth boards, designed to offer a platform for experimenting with the versatile PolarFire SoC — a high-performance low-power half that mixes a field-programmable gate array (FPGA) material with laborious RISC-V CPU cores. Now, they’re joined by a smaller sibling: the low-cost but feature-rich PolarFire SoC Discovery Package.
Because the title implies, the Discovery Package targets these simply setting out on their journey with PolarFire SoC elements — bringing down the barrier to entry with a far decrease buy value than its predecessors. Whereas that does imply the loss of some options, the Discovery Package retains all the things it’s worthwhile to get began working with bare-metal RISC-V, embedded Linux, and Libero SoC-based FPGA growth.
Let’s take the brand new board for a spin, and see the way it stacks up in opposition to its predecessors.
The {hardware}
The smallest of the “Package” household, the Discovery Package drops the PCI Categorical connectivity but retains a gigabit Ethernet port. (📷: Gareth Halfacree)
- FPGA: Microchip PolarFire SoC MPFS095T-1FCSG325E, 93k LEs (4LUT & DFF), 292 math blocks (18×18), 8× Person DLLs, 8× Person PLLs
- CPU: 4× SiFive U54 RV64GC at 667MHz (3.125 CoreMarks/MHz, 1.714 DMIPS/MHz), 1× E51 RV64IMAC at 667MHz
- GPU: None
- RAM: 1GB LPDDR4, 6.7Mb whole FPGA RAM as 308× 20kb LSRAM blocks, 876× uSRAM blocks (64×12),
- Storage: microSD card (not included)
- Networking: 1× gigabit Ethernet
- Serial: 3× UART (through 1× USB Kind-C connector)
- Growth: Raspberry Pi-compatible 40-pin GPIO header, mikroBUS header, MIPI RX, eight-digit seven-segment show header
- Programmer: FlashPro 5 embedded, no extra {hardware} required
- Extras: 2× push-button switches, 8× DIP switches, 8× user-addressable LEDs
- Energy: 5V through USB Kind-C or DC barrel jack (naked wire enter on Rev. 1)
- Dimensions: 104×84mm (round 4.1×3.3″)
- Pack Contents: PolarFire SoC Discovery Package board, stand-off pillars (pre-mounted), USB Kind-C cable
- Value: $132
The PolarFire SoC Discovery Package is the smallest in Microchip’s PolarFire SoC board household but, coming in at round 4.1×3.3″ — a large discount in dimension in comparison with the 7.3×5.3″ PolarFire SoC Icicle Package which preceded it. The chip at its coronary heart has additionally shrunk: slightly than the PolarFire SoC MPFS250T-FCVG484EES of the Icicle Package with its 256k logic components (LEs), the Discovery Package comes with the extra compact MPFS095T-1FCSG325E providing 93k LEs.
The chip at its coronary heart could also be smaller than the one on the Icicle Package, however that is to not say the Discovery Package does not have room for some comparatively advanced designs. (📷: Gareth Halfacree)
A fast take a look at the specs sheet reveals the place different areas have been trimmed, too. The place the Icicle Package comes with 2GB of LPDDR4 reminiscence, the Discovery Package has solely 1GB; the place there’s 8GB of eMMC storage on-board the Icicle Package, the Discovery Package wants you so as to add a microSD card to your procuring basket; the Icicle Package’s two Ethernet ports have been diminished to 1 on the Discovery Package, although fortunately this nonetheless retains its gigabit efficiency.
Anybody planning to work with high-speed peripherals will probably be disenchanted to search out the PCI Categorical slot of the Icicle Package completely eliminated, although it is hardly stunning given the dimensions of the Discovery Package. Not all space-saving choices are unwelcome, although: the somewhat-confusing three micro-USB ports of the Icicle Package have been ditched in favor of a single USB Kind-C port, which handily pulls double responsibility as a triple-UART serial bus and interface to the embedded FlashPro 5 programmer — you will want no extra {hardware} to blow your designs onto the PolarFire SoC’s FPGA material.
Different options which have survived the downsizing embrace a full Raspberry Pi-style 40-pin general-purpose enter/output (GPIO) header put in, as with Microchip’s earlier boards, at 180 levels to the Raspberry Pi normal so add-on boards dangle off slightly than over the board, a mikroBUS header, and an eight-way user-accessible DIP swap array plus two push-buttons switches alongside eight user-accessible “debug” LEDs. There’s even a header for an non-compulsory eight-digit seven-segment LED daughterboard, although sadly this isn’t included within the field.
The board consists of Raspberry Pi-style GPIO, mikroBUS, and MIPI RX connectivity, plus a header (bottom-right) for a seven-segment show board. (📷: Gareth Halfacree)
You will not discover any form of show output on the board, both, which given the dearth of graphics processor on the PolarFire SoC is comprehensible. Flip the board over, although, and one can find a welcome shock: a MIPI RX port, designed to be suitable with the Raspberry Pi Digital camera Module vary of Digital camera Serial Interface (CSI) picture sensor modules. Lastly, there is a DC jack for non-compulsory 5V energy when the board cannot be pushed over its USB Kind-C connector — a Revision 2 improve over a bare-wire enter on the unique Revision 1, as pictured. Apparently, Microchip recommends, although doesn’t provide, a 5V 3A energy provide — however in our testing the board not often went above a 0.65A draw.
The software program
The out-of-box expertise of the Discovery Package is quite a bit just like the Icicle Package, and the Video Package too, and facilities across the puzzle of getting Libero SoC — Microchip’s FPGA design suite — arrange and licensed. In comparison with after we first sat down with the Icicle Package, again in 2022, issues have improved barely: the necessary licensing server now installs robotically with Libero SoC itself, slightly than being hidden away as a definite obtain elsewhere on Microchip’s web site.
Establishing the {hardware} is simple; establishing the software program takes a little bit extra time, because of an archaic software program licensing system. (📷: Gareth Halfacree)
Past that, although, it is a acquainted story. For those who’re new to the Microchip ecosystem, the very first thing you will should do is join Microchip Direct. From there you’ll be able to obtain Libero SoC for Home windows and chosen Linux distributions, although not macOS — and should you’re trying to observe all Microchip’s tutorials as-written, you will want two variations put in side-by-side: Libero SoC 2023.2 and Libero SoC 2024.1.
As soon as put in, you will have to generate a license earlier than you’ll be able to really run Libero SoC — there isn’t any trial interval or feature-limited free tier, although just like the Icicle and Video Kits the Discovery Package features a lifetime-renewable “Silver” license as normal. Head to the licensing aspect of Microchip Direct and you will be requested to enter your laptop’s MAC tackle — taken in an effort to tie the license to a single machine, although with the caveat that it will get simply confused by units with a number of community playing cards — after which wait as much as 45 minutes for the license to reach through e-mail.
If you get the license, you will have to edit the file as a way to add your machine’s hostname and the paths of the varied licensing binaries. Lastly, you progress the license file into the identical folder as mentioned binaries and execute the licensing server. If this all feels like a whole faff, it’s — and after 12 months you will have to generate an all-new license, edit it once more, and transfer it into place, because the bundled Libero SoC Silver license lasts just one 12 months per technology.
Get used to seeing this: you will have to preserve the licensing agent operating within the background everytime you wish to use Libero SoC. (📷: Gareth Halfacree)
This has been a ache level for so long as Libero SoC has existed, however as the price of suitable FPGA growth boards falls it turns into more and more laborious to defend. Given Microchip’s curiosity in seeing the Discovery Package picked up by universities as a instructing device, it is notably obtrusive: a course would simply burn via the primary scheduled lesson merely getting the software program arrange and licensed on college students’ personal machines. Issues aren’t helped by Microchip’s continued insistence in splitting up documentation: the Discovery Package Person Information hyperlinks you out to no fewer than 4 different paperwork as a part of its “Software program Settings” part.
The Discovery Package comes with a brand new little bit of software program, too, not beforehand seen within the Icicle and Video Kits: a graphical person interface for Microchip’s demo utility, a finite impulse response (FIR) filter operating on the PolarFire SoC’s FPGA material. This, sadly, is Home windows-exclusive — and you may want both Libero SoC or the license-free FlashPro Categorical put in on the identical system as a way to get the required USB UART drivers in place.
Getting began
The FIR demo, dubbed Software Be aware 5165, is a pre-prepared design, created utilizing Libero SoC, which implements a 127-tap FIR filter with reloadable coefficients, a 256-point quick Fourier rework (FFT) filter, and a UART interface to the host machine’s graphical interface — developed for Microchip by Nationwide Devices.
Microchip’s flagship demo reveals the PolarFire SoC’s capabilities as a FIR filter — although it is a one-shot, slightly than streaming, instance that fails to indicate off its efficiency. (📷: Gareth Halfacree)
After putting in both Libero SoC or FlashPro Categorical and the Nationwide Devices GUI on a Home windows 10 or Home windows 11 machine with a free USB port, the pre-compiled “job” file could be flashed onto the PolarFire SoC in a few minutes. Due to the board’s built-in FlashPro 5 programmer, there isn’t any want for separate {hardware} — and its low energy draw means all you want is the bundled USB Kind-C cable between the Discovery Package and the laptop computer.
As soon as the design is flashed Microchip’s documentation walks step-by-step via utilizing the GUI to generate the filter coefficients and enter sign, then connecting the the software program to the Discovery Board to ship the enter to the FIR filter and obtain its output. What it does not do, sadly, is clarify what precisely it’s you are doing, what you are seeing, or provide any additional steering on experimenting with the FIR filter with your individual inputs and settings.
Microchip’s Libero SoC documentation guarantees a take a look at the FIR filter, however as a substitute simply walks you thru making a easy AND gate. (📷: Gareth Halfacree)
What it does present, as soon as once more, are hyperlinks to separate paperwork for every of the IP blocks used within the demo’s design — such because the FIR filter itself, documented in an expansive 63-page PDF. A separate information, linked from the Discovery Package product web page, seems by the desk’s heading to supply info on producing a FIR filter design your self utilizing Libero SoC — however in reality is a straightforward information to creating an AND gate that makes use of the 2 push-button switches as inputs and the primary of the eight “debug” LEDs as its output.
Linux lite
The FIR demo exists to showcase the capabilities of the PolarFire SoC’s FPGA material, however that is solely half the story. Because the title suggests, the PolarFire SoC is a system-on-chip — which means it has not solely the user-definable FPGA material however laborious processor cores, a quartet of 64-bit RISC-V cores from SiFive plus a fifth “monitor” core. These run at 667MHz, delivering a single-core efficiency round a 3rd once more as performant for frequent workloads because the 1GHz Arm core of a first-generation Raspberry Pi Zero regardless of the slower clock pace.
A fast re-flash of the FPGA material and bring-your-own microSD card will get a Yocto-based Linux picture up and operating. (📷: Gareth Halfacree)
Just like the Icicle Package and Video Package, the Discovery Package can run Linux — although with no on-board storage you will want to produce your individual microSD card. Microchip gives a Yocto board help bundle (BSP), utilizing which you’ll be able to construct your individual distribution; for the impatient, the corporate additionally provides a easy pre-prepared root filesystem picture you’ll be able to obtain and flash to your microSD card.
Earlier than you’ll be able to boot Linux, although, you will should flash the FPGA with Microchip’s Linux-supporting gateware. That is downloadable from GitHub, in a separate repository to the filesystem picture, and flashes in a few minutes utilizing FlashPro Categorical — with or with out Libero SoC put in and licensed within the background.
The downloadable distribution will really feel extraordinarily restricted for anybody coming from a desktop atmosphere. There is no bundle supervisor, the Ethernet port is configured for link-local connectivity solely with no dhclient put in, although as soon as you have sorted that out you are no less than given an on-by-default SSH server — which robotically logs you in as root with no password required, so anybody taking part in on a shared community is suggested to spend a little bit time locking the system down earlier than connecting the Ethernet cable.
The RISC-V cores on the PolarFire SoC run at 667MHz, but outperform the 1GHz Arm core on the unique Raspberry Pi Zero. (📷: Gareth Halfacree)
A problem for extra advanced functions — and one shared, by the way, by the Raspberry Pi Zero — is an absence of RAM. Whereas the Discovery Board itself has 1GB of LPDDR4 fitted, solely round 548MB is on the market to the person below Linux. It is attainable to keep away from the out-of-memory killer (OOMK) by including a swapfile, however throughput on the microSD card is sluggish — and fixed swapping is prone to put on the cardboard out sooner slightly than later.
As with its larger stablemates the Discovery Package additionally helps uneven multiprocessing (AMP), permitting the 4 cores on the PolarFire SoC to be break up into two separate techniques every appearing as a wholly distinct system. After all, this limits obtainable reminiscence even additional — whereas for these trying to get probably the most out of the board’s assets Microchip gives some commented pattern code for bare-metal use.
Conclusion
There are not any actual criticisms you’ll be able to stage in opposition to the PolarFire SoC Discovery Package that you may’t additionally stage in opposition to the larger and pricier Icicle Package and Video Package. Libero SoC continues to be a bear to arrange and license. The documentation continues to be unfold far and extensive, and has a gulf between the tip of its introductory examples and the beginning of the beginner-unfriendly highly-technical datasheets aimed toward skilled FPGA builders. The downloadable Linux distribution continues to be configured in uncommon methods and oddly restricted.
The PolarFire SoC punches effectively above its weight and sips energy, although 1GB of RAM is a little bit limiting for Linux use. (📷: Gareth Halfacree)
This time round, although, the criticisms are softened: at simply $132, the Discovery Package is significantly cheaper than any of Microchip’s different PolarFire SoC units. It has much less performance, certain, however it has sufficient to get you began — offering you are keen to place within the effort, after all.
This, once more, was true of the Icicle and Video Kits: the Discovery Package consists of that oh-so-tempting Raspberry Pi GPIO header and the compact mikroBUS header, however no tutorials for getting began with them — not from Linux and never from an FPGA design in Libero SoC. There’s nothing within the tutorials about utilizing the seven-segment show header, both, and no pattern tasks that use a digicam module linked to the MIPI RX port.
For somebody already well-versed with Microchip’s PolarFire SoC ecosystem, that is no large deal. For a hobbyist, it is a chance to experiment. For educators, although, it represents a time-sink: earlier than the Discovery Package may very well be utilized in a college atmosphere, somebody goes to should spend a very long time searching via varied sections of the Microchip web site and quite a few GitHub repositories pulling collectively disparate particulars right into a coherent lesson plan.
As at all times, there isn’t any faulting Microchip’s {hardware} — and if the corporate can get its documentation as much as par, the Discovery Package will probably be a sure-(Polar)hearth winner. (📷: Gareth Halfacree)
If the Discovery Package sells effectively, then, Microchip can be well-advised to spend among the proceeds on growing a single “trainer’s information” to the system — a doc that does not ship you to a different doc that sends you to a different doc, however as a substitute provides a one-stop store strolling you thru putting in the software program, experimenting with the FIR filter demo, taking part in with Linux, utilizing AMP, bare-metal programming, and utilizing Libero SoC to design one thing a little bit extra advanced than an AND gate. If it might use every of the board’s peripherals — together with that MIPI RX connector — even higher.
All of the {hardware} is there, and for simply $132 the Discovery Package is an absolute discount — the MPFS095T-1FCSG325E on the board prices over $90 extra as a naked part — however it’s now as much as Microchip to indicate the world why they need to purchase it.
The Discovery Package can now be ordered from Microchip, priced at $132; reductions can be found for qualifying college college students buying instantly from Microchip.
