EE366 – CMOS VLSI Design Basic Reference for VHDL Hardware ...

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1. EE366 – CMOS VLSI Design. Hardware Description Languages. Basic Reference for VHDL. • Reference book: – VHDL by Example by Douglas Perry ...
Basic Reference for VHDL • Reference book:

EE366 – CMOS VLSI Design

– VHDL by Example by Douglas Perry (e-version in the library).

• “VHDL cookbook” by Peter Ashenden, google it or download from: –

Hardware Description Languages

http://tech-www.informatik.uni-hamburg.de/vhdl/doc/cookbook/VHDL-Cookbook.pdf

• On-line Version of “ASIC – The Book” by M.Smith, Chapter 6 – http://www10.pcbcafe.com/book/ASIC/ASICs.php

• VHDL and VHDL FAQ from University of Hamburg: – http://tams-www.informatik.uni-hamburg.de/vhdl/

HDL – advantages w.r.t. schematic capture

Hardware Description Languages • Hardware: – Centered on HW implementations

• Description: – NOT procedural languages (no C) – NOT simulative languages – NOT synthesis languages

• Language: – Formal lang. (detailed description, BNF, definition…)

• • • • • • • •

Standardization Tool independence (Scirocco, ModelSim,…) Common semantics (no ambiguity) Hierarchy Levels of Abstractions Mixed descriptions Test-bench construction Enables simulation, synthesis,… modern design flows

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Commonly used HDLs • De facto standards in the industry and academia: – VHDL – IEEE standardization effort, common in Europe and in the academia worldwide, complex timing semantics, powerful modeling – Verilog – originally company proposed (Cadence), then standardized, more easy approach for classical design mindset, not as extended

VHDL - summary • • • • • • •

Structural vs behavioral modelling Process vs. Component Discrete Event Time Model Interprocess communication (signals) Timing model Signals vs. Variables Sensitivity list

VHDL • Very High Speed ICs (VHSIC) HDL • DARPA proposal for exchange in big digital projects • Then IEEE standards • Two subsequent “big” standardizations: 87 and 93, with relevant differences, mostly backward compatible

VHDL - Example • Counter (see Cookbook) http://tech-www.informatik.uni-hamburg.de/vhdl/doc/cookbook/VHDL-Cookbook.pdf

entity count2 is generic (prop_delay : Time := 10 ns); port (clock : in bit; q1, q0 : out bit); end count2;

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Architecture (Beh)

Architecture (Struct) q0

architecture behaviour of count2 is begin count_up: process (clock) variable count_value : natural := 0; begin if clock = '1' then count_value := (count_value + 1) mod 4; q0