VHDL

The VHSIC Hardware Description Language (VHDL) is a formal notation intended for use in all phases of the creation of electronic systems. Because it is both machine readable and human readable, it supports the development, verification, synthesis, and testing of hardware designs, the communication of hardware design data, and the maintenance, modification, and procurement of hardware.

VHDL is the preferred language in developments initiated or led by the European Space Agency.

A structured VHDL design method

In order to overcome the limitations of the classical 'dataflow' design style (large number of concurrent VHDL statements and processes, leading to bad readability and increased simulation time), a 'two-process' coding method is proposed: one process contains all combinational logic, whereas the other process infers all (and only) the registers. The paper further introduces the use of record types to increase readability and the safe use of variables to reduce simulation time. The method has been applied on several designs made by or for ESA. A presentation/lecture is also available.

• Author of both documents: Jiri Gaisler, Copyright Gaisler Research (pdf available)

VHDL Modelling Guidelines

The purpose of these guidelines is to ensure a good coding standard for VHDL, w.r.t. to readability, portability and a high level of verification. There are separate sections dealing with specific requirements for VHDL models for component simulation, board-level simulation, system-level simulation and testbenches.

• Author: Peter Sinander (pdf available)

The VHDL Standard Report

An overview of the current (May 1994) status of the VHDL standard and associated activities within the IEEE, EIA, and ESPRIT projects. An extensive summary of VHDL repositories is included, together with a list of European VHDL tools. (pdf available)

The Usage of VHDL in the European Space Agency

Outlines how VHDL is used in European Space Agency activities, in particular focusing on the need for modelling guidelines and an approach to use VHDL for board-level simulation.

• Author: Peter Sinander (pdf available)

Accelerated Verification of Digital Devices Using VHDL

This paper presents two aspects for improving the verification of microprocessors; program-less verification, and methods for handling large differences in abstraction level between a reference model and the actual design. Program-less verification is a type of pseudo random verification where the notion of a software program executing on the microprocessor has been abandoned.

• Author: Sandi Habinc and Peter Sinander (ESA/ESTEC TOS-ESM) (pdf available)

VHDL Models for Board-level Simulation

This document provides recommendations for development and usage of VHDL models intended for Board-level simulation. The purpose of these recommendations is to define modelling criteria that will produce models that are highly accurate in both functionality and timing, and that will provide sufficient simulation performance to facilitate long simulation runs.

• Author: Sandi Habinc (pdf available)