ghdl-examples

VHDL examples simulated using GHDL.

Install GHDL and GTKWave on Ubuntu 22.04

sudo apt update
sudo apt install ghdl gtkwave

Install GHDL from Source

If you get the following error:

error: unit "numeric_std" not found in library "ieee"

then you can build ghdl from source

sudo apt update
sudo apt install gnat
git clone https://github.com/ghdl/ghdl
cd ghdl
./configure
make
sudo make install

Compile VHDL Blinky RTL and Testbench

There are two steos to compile a VHDL program with GHDL. The first step is to analyze the VHDL source files and the second step is to elaborate, producing the compiled executable.

ghdl -a --std=08 blinky.vhd blinky_tb.vhd
ghdl -e --std=08 tb

Simulate VHDL Blinky with GHDL

The simulation is run with the -r option and the signal waveform is output with the --vcd option. A VCD file is an ASCII text Value Change Dump file captures signal transitions from the simulator.

ghdl -r --std=08 tb --vcd=test.vcd

View Signal Waves with GTKWave

gtkwave test.vcd