VHDL 101

Chapter 3. Loop 1 – Going with the Flow

This first pass presents the “30,000 foot view” of the language – what are the key parts, the concepts of signals and concurrency, and some basic concurrent operations that can be performed on signals.

3.1. The Shape of VHDL

Let's take a look at the typical parts of a single VHDL module. A module contains two basic parts – one covers the connections made between this module and other modules (the “outside world” which may be the pins on an FPGA package or other modules within the design) and the other part, an unambiguous description of the behavior of the module. Modules may be combined in parallel or hierarchically (see Figure 3.1).

Figure 3.1 The Shape of a VHDL Module.

This is a good place to briefly discuss ...