SymbiFlow Architecture Definitions

This repository is used during the development of architecture support in SymbiFlow, if you are looking to use the toolchain you should start with the symbiflow-examples repository.

This repo contains documentation of various FPGA architectures, it is currently concentrating on;

• Lattice iCE40

• Xilinx Series 7 (Artix 7 and Zynq 7)

• Kokoro Build Status

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The aim is to include useful documentation (both human and machine readable) on the primitives and routing infrastructure for these architectures. We hope this enables growth in the open source FPGA tools space.

The repo includes;

• Black box part definitions
• Verilog simulations
• Verilog To Routing architecture definitions
• Documentation for humans

The documentation can be generated using Sphinx.

Getting Started

To initialize submodules and setup the CMake build system, from the root of the symbiflow-arch-defs directory run:

make env

To build all demo bitstreams there are 3 useful targets:

# Build all demo bitstreams, targetting all architectures
make all_demos

# Build all 7-series demo bitstreams
make all_xc7

# Build all ice40 demo bitstreams
make all_ice40

Specific bitstreams can be built by specifying their target name, followed by a suffix specifying the desired output. For example, the LUT-RAM test for the RAM64X1D primative is called dram_test_64x1d. Example targets are:

# Just run synthesis on the input Verilog
make dram_test_64x1d_eblif

# Complete synthesis and place and route the circuit
make dram_test_64x1d_route

# Create the output bitstream (including synthesis and place and route)
make dram_test_64x1d_bin

# Run bitstream back into Vivado for timing checks, etc.
make dram_test_64x1d_vivado

Tools installed via submodules

• third_party/netlistsvg Tool for generating nice logic diagrams from Verilog code.

• third_party/icestorm Bitstream and timing database + tools for the Lattice iCE40.

• third_party/prjxray Tools for the Xilinx Series 7 parts.

• third_party/prjxray-db Bitstream and timing database for the Xilinx Series 7 parts.

Tools installed via conda

• yosys Verilog parsing and synthesis.

• vtr Place and route tool.

• iverilog Very correct FOSS Verilog Simulator

Tools potentially used in the future

• verilator Fast FOSS Verilog Simulator

• sphinx Tool for generating nice looking documentation.

• breathe Tool for allowing Doxygen and Sphinx integration.

• doxygen-verilog Allows using Doxygen style comments inside Verilog files.

• symbolator Tool for generating symbol diagrams from Verilog (and VHDL) code.

• wavedrom Tool for generating waveform / timing diagrams.

Resource Requirements

To run examples provided, please make sure these resources are available:

• Memory: 5.5G
• Disk space: 20G

Development notes

Because symbiflow-arch-defs relies on yosys and VPR, it may be useful to override the default packaged binaries with locally supplied binaries. The build system allows this via environment variables matching the executable name. Here is a list of common environment variables to defined when doing local yosys and VPR development.

• YOSYS : Path to yosys executable to use.
• VPR : Path to VPR executable to use.
• GENFASM : Path genfasm executable to use.

There are more binaries that are packaged (e.g. VVP), but the packaged versions are typically good enough for most use cases.

After setting or clearing one of these environment variables, CMake needs to be re-run.