Bluespec Announces Flute

Bluespec, Inc. releases a second family of open-source RISC-V processors to spur open innovation:

December 13, 2018 – Bluespec Inc. has released Flute, its second in a family of commercially supported open-source RISC-V processors.

Flute is a configurable 5-stage application processor complementing the previously released 3-stage Piccolo microcontroller, both of which are suitable for IoT. The initial release provides synthesizable Verilog for a bare metal RV32IMA core and a supervisor level RV64IMA core. Future releases will add floating point and compressed instructions (RV32GC/RV64GC) and run Linux and FreeRTOS.  The Flute download (here) provides working Verilator and Icarus simulations and the Verilog has been tested in Xilinx UltraScale/UltraScale+ boards.

“The availability of commercially-backed open-source processor cores is a unique RISC-V value proposition”, says Rick O’Connor, Executive Director of the RISC-V Foundation. “With the emergence of the free and open RISC-V ISA an open-source business model is now possible for processor IP. This will certainly help RISC-V ignite a new era of hardware innovation, as Linux did for software.”

RISC-V has demonstrated that open collaboration can produce an industrial strength ISA. The independent RISC-V Foundation ( maintains the ISA and has over 200 members, including many notable high-tech companies. RISC-V dominates computer architecture

“We are using Bluespec’s Flute core as a fast and efficient way to take to market our Posit Numeric Unit IP,” says Anantha Kinnal, Co-founder & Director of Calligo Technologies, an HPC/AI Company based in Bangalore, India. “It provides us customization opportunities, an ability to focus on our value-added technology and confidence to go to market with the necessary commercial support.”


Bluespec, Inc. provides hardware development tools that reduce the time, effort and risk of developing RISC-V processors and systems. It is a founding member of the RISC-V Foundation and a leader in the RISC-V open-source movement that is paving the way for a new wave of open innovation in processor-based systems.

Posted by on December 13, 2018
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