This directory provides a tutorial on how to create structural descriptions, which are generally just code representations of a schematic. A schematic is just an interconnection of existing components, which can be any type of logic, and any level of granularity.
For structural descriptions, designing the circuit means creating the schematic. For every component in the schematic, you will simply instantiate an existing entity (or create one if necessary), and then connect them together as shown in the schematic. The primary creativity in structural descriptions is identifying patterns (or exceptions) in the structure that can be described with generate constructs, as the examples will show.
- 4:1 mux
- Illustrates the basic techniques for converting a schematic (in this case mux4x1.pdf) into VHDL code.
- Ripple-Carry Adder
- Introduces the for-generate construct.
- See the schematic ripple_carry_adder.pdf for reference.
- Important point: Use the "for generate" statement anytime that there is a pattern in a structural description. This construct will allow you to specify very large structures with very little code.
- Delay
- Introduces arrays and if generate.
- See the schematic delay.pdf for reference.
- Add Tree (TBD)
- Introduces recursion.