Learn VHDL with Real Code Examples

VHDL describes actual digital hardware, not software.

It supports concurrency, signals, timing, and low-level digital behavior.

Widely used in aerospace, defense, semiconductor design, and FPGA development.

Entity-architecture separation

Signals, processes, and concurrent statements

Generic parameters for configurable design

Records, arrays, and strong data typing

Testbenches for simulation

Entities and architectures

Signals and variables

Concurrent vs sequential execution

Processes and sensitivity lists

FSMs, datapaths, and timing

src/ - VHDL source files

tb/ - testbenches

pkg/ - custom packages

constraints/ - FPGA pin mappings

simulation/ - waveform files

Write VHDL entity & architecture (.vhd)

Compile with GHDL or vendor compiler

Run simulation with testbench

Analyze waveforms in GTKWave

Synthesize for FPGA vendor tools

Beginner: logic gates, multiplexers

Intermediate: counters, registers, FSMs

Advanced: CPU cores, DSP pipelines

Expert: full SoCs or radiation-hardened FPGA architectures

More verbose but more structured than Verilog

Better for large systems than SystemVerilog in some industries

Preferred in Europe and aerospace/defense

Strong typing reduces design bugs

Slower for rapid prototyping than Verilog

1980s – Initial DoD development

1987 – First IEEE 1076 standard

1993 – Major updates with modern features

2002 – Extended operators and libraries

2008+ – Enhanced synthesis and modern revisions

Entity: hardware interface

Architecture: implementation

Process: sequential logic block

Signal: concurrent hardware connection

Testbench: simulation wrapper