What’s the big deal about this board?
HiFive Unleashed is the world’s first multi-core RISC-V Linux
Development Board, and the Freedom U540 is the world’s first commercial
multi-core coherent RISC-V based SoC. For the RISC-V development
community and ecosystem, it’s an extremely exciting milestone that’s
been 8 years in the making.
Who should buy this board?
You should buy this board if you:
- Are a serious software developer who wants to develop on RISC-V
- Are a kernel developer, Linux hacker, or an open-source software developer who wants to port your favorite software project to RISC-V
- Are looking to evaluate SiFive U54-MC Core IP
- Want to own fastest RISC-V SoC in the world
- Have been waiting for multi-core, Linux capable RISC-V devices
- Want to evaluate or learn more about high-performance RISC-V devices
- Want to support open-source hardware
- Simply want to support the Open Source Movement!!
Why is this important?
In a very short period of time, RISC-V has grown from an academic
project, to commercial curiosity, to a widely accepted alternative to
existing ISA, to demonstrable market success. SiFive has been there
every step of the way and this is the next evolution of RISC-V.
Why is the supply of HiFive Unleashed boards so limited?
This is the initial run of the Freedom U540 SoC and the HiFive
Unleashed board, and we wanted to get it in the hands of the most
advanced open-source developers as quickly as possible. Future runs
of the SoC and board will be in higher volumes.
Why is the price so high, compared to the HiFive1 and other widely-available embedded development boards?
This board is intended for software developers, and as such we made
decisions such as having 8GB DDR4 memory, a large SPI Flash,
multiple headers and a high-speed FMC expansion port to maximize the
development value of the board. Production costs are also relatively
high in this early, limited volume build. We are working hard to
bring down the cost in future boards to enable more developers with
Linux-capable, Freedom Unleashed RISC-V SoCs.
Is the board you showed at FOSDEM the same as the production version?
At FOSDEM, we showed the first prototype board off the line. The
production version may have slightly different memory configuration
and board markings, but it will be the same Freedom U540 SoCs.
Is the Freedom U540 SoC open-source?
The Freedom U540 SoC is based on the Freedom Unleashed Platform, which
has been open sourced. The Freedom Platform is available at
and is maintained by SiFive. In the Freedom Platform, you will find:
- RISC-V Rocket CPU
- TileLink, a free and open coherent SoC interconnect
- Low-speed Peripherals: SPI, UART, PWM, GPIO, I2C
- High-speed Xilinx FPGA Peripheral Wrappers: DDR, PCIe blocks
- The Freedom U540 contains many 3rd-party IP: cells, pads, PLL, OTP, DDR, GbE, ROM, which are not open-sourced
Wouldn’t HiFive Unleashed have been cheaper as an FPGA?
While it would have been possible to create an FPGA version of
Freedom U540 in a complex FPGA, the performance would have been
significantly less than a 28nm SoC running up to 1.5 GHz. Nothing
beats actual silicon when it comes to software development and
verification. The cost of a complex FPGA board is also significant
and it would take a multi-thousand dollar FPGA board to reasonably
fit the Freedom U540 on to it. For microcontroller-class
applications, our Freedom Everywhere Core IP is available to download
from our site as FPGA bitstreams that can be implemented in a
low-cost FPGA development board.
Is the HiFive Unleashed board open-source?
Yes, we will be releasing the schematics and layout of the HiFive
Unleashed, just like we did for the
How does the HiFive Unleashed compare to the HiFive1 board?
The HiFive1 board is a very affordable microcontroller board based on
the Freedom E310 RISC-V based SoC and is intended for microcontroller
applications. The HiFive Unleashed features a much more powerful,
multicore CPU, the U54-MC, which has an MMU, virtual memory, and
privileged mode support which allow it to support full featured
operating systems such as Linux. The ChipLink port on the HiFive
Unleashed board supports additional expansion boards to allow
developers to prototype high-performance RISC-V-based systems such as
storage, networking, and data-center accelerators
What’s the core clock speed?
All the cores on the Freedom U540 can run up to 1.5 GHz.
You listed some of the peripherals of the HiFive Unleashed, such as Gigabit Ethernet, MicroSD, and the FMC expansion connector. What other interfaces are supported? What expansion boards can be attached to the FMC interface? How can I add PCIe capability to the HiFive Unleashed?
The HiFive Unleashed includes a typical suite of developer-friendly
ports such as Gigabit Ethernet, UART over USB, MicroSD, PWMs, I2C,
SPIs, and GPIOs. The FMC connector enables more functionality with
expansion cards specifically built for the HiFive Unleashed that
will break out many high-speed peripherals including PCIe and SATA.
Details will be announced soon.
At the last workshop, you showed a connection to a Microsemi Polarfire™ FPGA. Is that still being planned?
An expansion board with the Microsemi Polarfire FPGA will be
Where can I find software for the HiFive Unleashed?