std_logic vs std_ulogic

std_logic vs std_ulogic

VHDL includes few built-in types but offers several additional types through extension packages. Two of the most widely used types are std_logic and std_ulogic. The difference between them is that the former is resolved while the latter isn’t. Before we go on to investigate what it means that a type is resolved, let’s first look…

Delta cycles explained

Delta cycles explained

Delta cycles are non-time-consuming timesteps used by VHDL simulators for modeling events during execution of VHDL code. They are events that happen in zero simulation time after a preceding event. VHDL is a parallel programming language, while computers and CPUs work in a sequential manner. When a normal programming language is run, the CPU executes…

One-process vs two-process vs three-process state machine

One-process vs two-process vs three-process state machine

Most of us stick to a certain way of writing a state machine. Perhaps you type out the construct that you are most familiar with without giving much thought to the alternatives. Depending on the method that you were taught when learning VHDL, you may prefer one method to another. Over the years, I have…

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