A collection of MyHDL cores and tools for complex digital circuit design
Python Verilog VHDL Other
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NickShaffner and cfelton Remove phantom warnings in verilog conversion related to Xilinx devic…
…e_clock_mgmt_prim (#54)

* Remove phantom warnings related to Xilinx device_clock_mgmt_prim

* Also removed phantom conversion warning about clockin not being read
Latest commit 4d1c505 Aug 16, 2016


NOTE the following is a work-in-progress (WIP) and has not reached a minor release point. If you happen to come across this public repository feel free to try it out and contribute. This repository will be unstable until the first minor release 0.1. This repository is a merge of the mn and gizflo projects.

Build Status Code Health Coverage Status Documentation Status Join the chat at https://gitter.im/cfelton/rhea


The rhea python package is a collection of HDL cores written in MyHDL. The rhea package also includes a small set of utilities to augment the myhdl types and functions as well as FPGA build automation tools.

the name

Pronounced ray (as in ray-gun), just a random name and not pronounced the same as the bird or moon.


  • myhdl currently 1.0dev (pre-release)
  • pytest for the test suite
  • Pillow >= 2.9, some video tests utilize the imaging library
  • FPGA vendor tools, only for automated build tools.

documenation and resources

If you are not familiar with myhdl starting with the myhdl manual and examples is recommended. General myhdl questions can be answered on the #myhdl IRC channel or on the myhdl mailing-list.
I am often available to answer rhea specific questions on the previously mentioned communications or the rhea gitter can be used.

general comments

IMPORTANT NOTE this repository is under development and is using features from a development version of MyHDL (1.0dev). If you wish to try out this package get the development myhdl (you will need to clone it and install the source). The first rhea release will not occur until myhdl 1.0 is released (probably much later).

Getting close to the fist minor release. The first minor release will contain a small collection of documented cores and frameworks (see below).

This code/package is licensed under the MIT license. This allows anyone to use the package in their projects with no limitations.
Questions and other license options email me.

The following are the definition of some terms used in this README :

  • cores : the building blocks of a system. Also, know as IP (intellectual property).

  • system : the digital design being implement, synonymous with system-on-a-chip, not using the term system-on-a-chip (SoC) because SoC it is typically reserved for systems that contains a CPU. In this document and the example the system can be a SoC or other complex digital design.

  • register : collection of bits that retain state.

  • register file : collection of same-sized registers, a register file is organized into read-write entities and read-only entities. A register-file is a programming/configuration interface to a core.

  • CSR: control and status registers also known as config and status.
    This term is commonly used for the memory-mapped interface to the cores.

getting started

To get started with the latest version (repo version) checkout out the code and run setup in develop mode. The dependencies listed above need to be installed.

Install the latest myhdl.

  >> git clone https://github.com/jandecaluwe/myhdl
  >> sudo python setup.py install
  >> cd ..


  >> pip install git+https://github.com/jandecaluwe/myhdl

After the dependencies have been installed clone this repository to get started.

  >> git clone https://github.com/cfelton/rhea
  >> cd rhea
  # requires setuptools
  >> sudo python setup.py develop

running tests

The tests can be run from the test directory.

  # attempt to run the tests
  >> cd test
  >> py.test

generating bitstreams

If FPGA vendor tools (Xilinx, Altera, Lattice, Yosys) are installed the build examples can be run to generate bitstreams.

  # try to compile one of the examples 
  # (requires FPGA tools installed)
  >> cd ../examples/build/
  >> python ex_xula.py


The test directory contains test for the different cores in the package.

Run the tests in the test directory:

>> cd test
>> py.test

Run the tests in the examples directory:

>> cd examples
>> py.test


In the example directory are projects that demonstrate how to build systems using the cores and various tools and target a particular FPGA development board. The examples/build contains LED blinky examples for many different boards.


The following is a list of cores being developed for the 0.1 release, an [x] indicates the core has been completed and verified on an FPGA development board.

* Complete but dysfunctional. These are old cores that were working on an FPGA, at one point in time, but have not been updated in ages.