How to manually build and simulate a VHDL project? A brief guide is provided in this presentation. GHDL was chosen to approach the goal. It is a free and open-source VHDL simulator published at https://github.com/ghdl/ghdl. The presentation was given at the Faculty of Informatics of Masaryk University in 2018 within the PA176 Architecture of Digital Systems II course.

1. VHDL Building
Dominik Salvet
github.com/dominiksalvet

2. Common VHDL Design Flow

3. FPGA-Delivered IDEs

4. GHDL Compiler and Simulator

5. Then Why Use GHDL?
●
speed (it is not an interpreter)
●
runs on Windows, Linux and even on macOS
●
target platform independent (Xilinx, Altera, Lattice)
●
easy start with manual building
●
decent documentation
●
it is open-source software (see this GitHub repository)

6. How To Use GDHL?
●
it is terminal-based program
●
very similar to gcc in terms of use
●
it has multiple back-ends, such as mcode, gcc and LLVM
● -a option
●
analyzes/compiles one or more files
●
creates object files as a result
● -e option
●
elaborates an unit (must be already analyzed)
●
creates an executable file (usable for test benches)

7. Example of Using GHDL
●
we need to follow the order of GHDL commands
●
simulate clk_divider module with associated clk_divider_tb
1.ghdl -a --std=93 clk_divider.vhdl
2.ghdl -a --std=93 clk_divider_tb.vhdl
3.ghdl -e --std=93 clk_divider_tb
4.ghdl -r --std=93 clk_divider_tb
or
./clk_divider_tb

8. Makefile
● a file used for make build automation
●
it can be used literally for any software to build
● it can be invoked by make command in the directory
containing the makefile or Makefile file
●
basically it contains a set of rules with the following form:
target: dependencies
system command(s)
● when used only make command, it will start from the first
stated target
● to choose the entry target, use make target command

9. Example of a Makefile (1)
clk_divider_tb: clk_divider_tb.o
ghdl -e --std=93 clk_divider_tb
clk_divider_tb.o: clk_divider_tb.vhdl
clk_divider.o
ghdl -a --std=93 clk_divider_tb.vhdl
clk_divider.o: clk_divider.vhdl
ghdl -a --std=93 clk_divider.vhdl

10. Example of a Makefile (2)
.PHONY: run clean
run: clk_divider_tb
ghdl -r --std=93 @<
clean:
rm -f clk_divider_tb
rm -f *.o
rm -f *.cf

11. Questions?
Dominik Salvet
I do not own copyright to images.