VHDL Syntax Introduction

In this article I am going to introduce and explain the syntax of the VHDL language. When working with VHDL there are various different keywords as in other languages. A list below contains multiple keywords used in the VHDL language.

Syntax

What does it do

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VHDL Comment

:=

Assigns an initial value

=>

Assignsobject on right value of object on left

<=

Assignsobject on left value of object on right

;

Indicatesend of line

:

Used to Specifya data type for an Object

‘1’

Value of a std_logic

“100”

Value of a std_logic_vector(3 bits)

Rising_edge

Refers to the rising edge of a signal

Entity

a primary design unit

Architecture

A secondary design unit

Port

interface definition, also port map

Generic

introduces generic part of a declaration

Signal

declaration that an object is a signal

Constant

declares an identifier to be read only

Begin

start of a begin end pair

End

part of many statements, may be followed by word and id

Others

Assigns all unpicked bits in a std_logic_vector, unsigned, or signed data type

These keywords are used in conjunction with different logical statements to produce hardware designs.