The HiFive Unmatched from SiFive ushers in a new era of RISC-V Linux development platform in a PC form factor. Powered by the SiFive Freedom U740 RISC-V SoC and targeted for creating RISC-V applications, the platform features 16 GB of 64-bit DDR4 memory operating at 2400 MT/s, high-speed interconnects with PCIe Gen 3 x8 operating at 7.8 GB/s, Gigabit Ethernet, and USB 3.2 Gen 1. Software development is supported with Freedom U-SDK from SiFive, which provides a fast and convenient software environment to quickly build and modify a custom Linux distribution for this RISC-V PC.

The Freedom U740 SoC is the highest performance RISC-V processor available today, and the Unmatched board is ready to be your next desktop.

History

In February 2018, SiFive launched the HiFive Unleashed board, a demonstration and evaluation board for the highest-performance RISC-V processor available at the time, the Freedom U540. While it did not include common PC interfaces like PCIe or USB, it offered expansion opportunities via a ChipLink high-speed serial interface. A few months later, the Microsemi HiFive Unleashed Expansion Board launched to supplement the Unleashed with PCIe, USB, HDMI, and a host of additional peripherals for experimentation and development. This combination brought a usable desktop RISC-V PC to users for the first time.

The Unmatched board is a significant performance iteration and cost reduction from this combination, and SiFive is proud to be able to be able to bring an exceptional RISC-V platform to an even wider audience of users and developers.

Features & Specifications

• SiFive Freedom U740 SoC (4 x U74 & 1 x S7 CPUs)
• 16 GB (64-bit) DDR4 memory
• 8-lane PCIe Gen 3 switch
• PCIe x2 to USB 3.2 Gen 1 bridge
• Four-port USB 3.2 Gen 1 hub
• 32 MB Quad SPI boot flash
• 256 KB EEPROM (for manufacturing data)
• 10/100/1000 Ethernet
• UART/JTAG support
• Onboard temperature sensor
• Onboard power management IC
• MicroSD card socket
• User I/O:
  • 4 x USB 3.2 Gen 1 Type A ports (1 charging port)
  • 1 x Micro USB UART/JTAG connector
• Expansion:
  • x16 PCIe Gen 3 Expansion Slot (eight lanes usable)
  • M.2 Key M Slot (PCIe Gen 3 x4) for NVMe 2280 SSD
  • M.2 Key E Slot (PCIe Gen 3 x1) for Wi-Fi / Bluetooth
  • Header for FU740 I/O (I2C, SPI, QSPI, GPIO)
• Mini-ITX form factor, 170 mm x 170 mm
• 24-pin ATX power supply connector

Block Diagrams

Support & Documentation

A full suite of documentation will be available on the SiFive website, including:

• Getting started guide
• Hardware reference manual
• Design files, including the schematic, BOM, and PCB layout

Additionally, the board will ship with a microSD card preloaded with the SiFive Freedom U-SDK, including these components:

• U-boot SPL (DRAM init)
• OpenSBI
• U-boot Proper
• DT data
• Linux Board Support Package (BSP) supporting:
  • PCIe switch
  • PCIe to USB bridge
  • USB hub
  • USB mouse/keyboard
  • Gigabit Ethernet
  • Thermal sensor
  • Power management IC (PMIC)
  • Third-party expansion cards currently being validated (not included):
    • M.2 Key E Wi-Fi / Bluetooth module
    • M.2 Key M NVMe SSD
    • PCIe GPU

What’s in the Box?

• HiFive Unmatched Mini ITX board, with onboard CPU and RAM
• 32 GB microSD card, preloaded with software
• Rear panel I/O shield
• M.2 screw package
• Chassis mounting hardware
• Cat-5 cable
• Getting started guide

A typical desktop PC build will need to add:

• Mini ITX-compatible case
• ATX or SFX power supply
• GPU
• M.2 2280 NVMe SSD
• Wi-Fi card

We are in the process of validating commodity SSD, GPU, and wireless card options. We will post fully validated recommendations in the coming weeks.