Tips and tricks for accomplishing things with VHDL
Many people struggle to understand the ModelSim/QuestaSim VHDL simulator’s workflow. I think that’s unnecessary because the basic workflow isn’t hard to learn.
I regard the graphical user interface (GUI) as a front-end for the commands listed in this article. For example, when you click the Compile button in the ModelSim GUI, it runs the vcom command back-end. The screenshot below shows the command echoed to the transcript window after we click the Compile button.
Professional VHDL simulators are more expensive than most individuals can afford. But fortunately, there are many free and legal alternatives that you can download and install.
Microsoft Windows is the easiest to install on, but many simulators also have a Linux version. FPGA vendors usually only support the Red Hat Linux distribution. But with a little effort, you can make it work in other distros, including Ubuntu.
Mac OS is the most challenging platform because there’s only one open-source simulator that works natively.
This tutorial shows how to install the Lattice iCEcube2 FPGA design software on Ubuntu 20.04. Instead of the Lattice Diamond Programmer, we will use the alternative programmer from Project IceStorm that works flawlessly on Ubuntu Linux.
The Lattice iCEcube2 FPGA design software only works on Red Hat-based Linux distributions out of the box. Fortunately, we can make it run perfectly on Ubuntu Linux by installing dependencies and making a few changes to our system.
The ModelSim version that comes with Intel Quartus Prime Lite Edition is a good alternative if you want to try out VHDL simulation on your home computer. The software is available for both Windows and Linux, but Intel only supports Red Hat-based distros like CentOS Linux.
Fortunately, you are just a few hacks away from ModelSim working nicely on your Ubuntu box.
I know that I have googled this at least a hundred times throughout my career as an FPGA engineer; how to check if all bits in a std_logic_vector signal are ‘0’ or ‘1’. Of course, you know a few ways to do it already, but you want to find the most elegant code that will work with vectors of any length. Right?
Let’s have a look at the best methods for checking that all the bits in a vector are set or unset.
