Kazhuu / vhdl-examples

VHDL examples for a different kind of topics

VHDL examples and components

This repository is my personal study notes and examples of VHDL language and FPGA hardware design. Various language features are explored with simple examples and some components are implemented as well. All language examples and components can be found under their related folders and subfolders. I hope someone else might find this information also useful.

Tools used

All code is written using Vim and some plugins. The plugins used are hdlcc and vim-hdl. These plugins together provide syntax checking and automatic compiling for simulation with ModelSim. Configuration file is named vimhdl.prj and Vim needs to be started in the folder with this file.

All automatically compiled code is placed in the .build subfolder. In this subfolder ModelSim can be started and it should read all compiled code and libraries without errors. ModelSim can be given with the design to simulate. For example:

cd .build/
vsim work.test

Then run example in ModelSim console with run and example should print the results and stop automatically.

Components are tested with VUnit Python based testing library. Repository root includes Pipfile which can be used with pipenv to create Python virtual environments VUnit installed and not populating your system's installation. Virtual environment installed and activated all tests can be run with python run.py at project root.

Missing VHDL topics

• Different ways to instantiate a component.
• Qualified expression.
• Configure examples.
• Use of generics.
• Block statements and signal kinds bus and register and how they behave.
• Shared variable and how to use.
• Different wait statements with process.
• Three main different ways to implement state machines.
• Use VHDL 2008 env package (std.env.finish for instance).
• Reduction operator e.g. xxx <= and yyy.
• Example to show that 'work' is not a library but a reference to same library where this element is defined (example: VUnit/vunit#497).