VHDL Overview

1
Chapter 1
VHDL - Overview and Application Field
2
VHDL - Overview and Application Field ( Intro. )

• What is hardware?
•  
• What kind of description?
• Hardware Description Language (HDL)
  "Programming"-language for modelling of
  (digital) hardware

3
Application of HDLs (1)
4
Application of HDLs (2)
5
Range of Use
6
VHDL - Overview

• Very High Speed Integrated Circuit Hardware
  Description Language
• Modelling of digital systems
• Concurrent and sequential statements
• Machine-readable specification
• Design lifetime gt designer lifetime
• Man- and machine-readable documentation
• International Standards
• IEEE Std 1076-1987
• IEEE Std 1076-1993
• Analogue- and mixed-signal extension VHDL-AMS
• IEEE Std 1076.1-1999
• Pure definition of language in the LRM (Language
  Reference Manual)
• No standards for application or methodolgy

7
VHDL - History

• early 70s Initial discussions
• late 70s Definition of requirements
• mid -82 Contract of development with IBM,
  Intermetrics and TI
• mid -84 Version 7.2
• mid -86 IEEE-Standard
• 1987 DoD adopts the standard -gt IEEE.1076
• mid -88 Increasing support by CAE manufacturers
  
• late 91 Revision
• 1993 New standard
• 1999 VHDL-AMS extension

8
VHDL - Application Field

• Hardware design
• ASIC technology mapping
• FPGA CLB mapping
• PLD smaller structures, hardly any use of VHDL
• Standard solutions, models, behavioural
  description, ...
• Software design
• VHDL - C interface (tool-specific)
• Main focus of research (hardware/software
  co-design)

9
ASIC Development
10
1.3 Concepts of VHDL
Execution of assignments Sequential Concurrent

Methodologies Abstraction Modularity
Hierarchy
11
Abstraction

• Abstraction is hiding of detailsDifferentiation
  between essential and nonessential information
• Creation of abstraction levelsOn every
  abstraction level only the essential information
  is considered, nonessential information is left
  out
• Equability of the abstractionAll information of
  a model on one abstraction level contains the
  same degree of abstraction

12
Abstraction Levels in IC Design
13
Abstraction levels and VHDL
14
Description of Abstraction Levels
15
Behavioural Description in VHDL
16
RT Level in VHDL
17
Gate Level in VHDL
18
Information Content of Abstraction Levels
19
Modularity and Hierarchy

• Partitioning in several partial designs
• Restrict complexity
• Enable teamwork
• Study of alternative implementations
• Soft macros
• Simulation models

20
Summary

• Hardware and software concepts
• Hardware is part of the system design
• Behavioural and RTL style
• Structure
• Concurrence (simultaneity (
• Sequential statements
• Description of timing behaviour is possible
• One language for model development and
  verification