Vision VHD-800 Dokumentacja Pobierz pdf (Strona 2)

1 Introduction

The VLSI design ﬂow is described in detail in the VLSI textbook. In Figure 1, a very rudimentary overview is given in order

to identify the subject of this exercise.

Algorithm Design

Architecture Design

VHDL Coding

Synthesis

Physical Design

behavioral VHDL

Netlist

Chip Layout

Netlist

Specification

Subject of this exercise

Figure 1: VLSI design ﬂow overview.

In this exercise, you will learn to generate a gate-level netlist from a behavioral VHDL description of the circuit by means

of the synthesis tool SYNOPSYS DESIGN COMPILER. This tool will convert your VHDL description into a corresponding

gate-level netlist.

To ensure that a custom design can ﬁnally be fabricated at the foundry, the SYNOPSYS DESIGN COMPILER gets told to use

only a predeﬁned selection of gates provided by the manufacturer, i.e., the gates which can actually be manufactured by

the foundry. The entirety of these gates are collected in a so-called standard cell library.

1.1 Software or Hardware

For all practical purposes, the syntax of VHDL is like most high-level programming languages. However the main purpose

of VHDL is to describe hardware. As hardware engineers, we are mostly forced to design circuits that meet certain

area, speed, and power requirements. We therefore need to know what hardware our carefully written code will result in.

Remember that each VHDL line will eventually contribute to the ﬁnal hardware. In this sense, the VHDL language is more

like a schematic editor, than a programming language.

Writing good VHDL code is the ﬁrst step to get exactly the desired circuit. Using realistic synthesis constraints with the

synthesis tools is the second step (you will learn how to set these constraints during this exercise). If done properly, these

two steps will allow you to describe and realize a very speciﬁc circuit that (hopefully) meets the design requirements.

2 Notation

Text-Based Command Inputs (Shell Commands): Throughout this exercise, different types of consoles will be used. In

order to avoid confusions and misunderstandings with regard to the provided commands (i.e., where you have to enter

them), Figure 2 shows an example of each of them. Furthermore, Figure 2c and Figure 2d illustrate examples, including

multiple-line commands and line breaks. It should be clear from the context in which window the commands provided in

the text have to be entered.

Files and Directories: File paths and directories, stated within this exercise, are always given relative to the root path of

your cockpit structure, except those during the preparation (cf. Section 3).

Student Task: Parts of the exercise where you are required to take action will be explained in a shaded box, just like

this paragraph.

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Vision VHD-800 Dokumentacja Strona 2