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.

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!!

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.

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.

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.

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.

The Freedom U540 SoC is based on the Freedom Unleashed Platform, which has been open sourced. The Freedom Platform is available at https://github.com/sifive/freedom 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

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.

Yes, we will be releasing the schematics and layout of the HiFive Unleashed, just like we did for the HiFive1.

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

All the cores on the Freedom U540 can run up to 1.5 GHz.

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.

An expansion board with the Microsemi Polarfire FPGA will be available.

We will support the HiFive Unleashed in the freedom-u-sdk. The repository is available at https://github.com/sifive/freedom-u-sdk, and pre-built software tools are at https://www.sifive.com/products/tools.