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Apr 19, 2019
Oct 19, 2019

Raven: An ASIC implementation of the PicoSoC PicoRV32

Designed by efabless engineering, San Jose, CA

Overview

The purpose of this repository is to provide a completely free and open-source simulation environment for the Raven chip. The Raven chip itself can be found in the efabless IP catalog. See https://efabless.com (registration is required to view the IP catalog. Regitration is free and validation is not required to view the catalog contents. However, validation is required to use the efabless design environments; e.g., to view the layout of the raven chip on the Open Galaxy design platform).

The simulation environment matches the reference design in the efabless IP catalog functionally, and can be used to write software/firmware that will run on the Raven test board.

The requirements for simulating the Raven chip are: iverilog (iverilog.icarus.com), and the RISC-V gcc configured for the RISC-V options used by the picoRV32 processor design. The best way to obtain the correct gcc cross-compiler is to install the picoRV32 source from github (https://github.com/cliffordwolf/picorv32). The Makefile in the picoRV32 repository automatically downloads and locally installs the correct gcc cross-compiler. In this repository, it is necessary to change the path to gcc in verilog/Makefile and verilog/*/Makefile to match the local installation. Once that is done, cd to the "verilog/" directory and run "make" to run the simulation test suite.

Documentation on the memory mapping and the SPI slave interface can be found in the "doc/" directory.

Summary

Raven is using a very popular 32-bit RISC-V core (PicoRV32) developed by Clifford Wolf, a well-known open source champion. The core was previously proven with an FPGA implementation and Raven is the first SoC built with it. The system integrator is our own Tim Edwards, another champion in the open source domain. Included below is a 15s video showing the wakeup, key features and a link to high-level datasheet.

Raven is now published in our marketplace for designers and partner companies to clone and customize starting from a silicon-proven point. It is also published on the RISC-V Foundation’s directory of designs (https://riscv.org/risc-v-cores)

RAVEN Block Diagram

RAVEN-PICORV32

Key Features

  • RISC-V CPU (PicoRV32)
  • SRAM 32x1024
  • 100 MHz clock rate
  • Programmable clock source
  • 16 channels GPIO
  • 2 ADCs
  • 1 DAC
  • 1 Comparator
  • Over-temperature alarm
  • 100 kHz RC oscillator
  • Programmable functions on GPIO outputs
  • Programmable interrupts on GPIO inputs

High-level Datasheet

Short Video showing initial wakeup