Several VHDL code examples are listed below. Each example includes the source code and simulation waveform. Also, at the footer of each example you can find a link to download both the model source and testbench files.
Note: The categories marked with an (includes exercises) have proposed exercises for you to practice. Check them out!
Generic up-down counter (includes exercises)
Parameterized PWM controller (includes exercises)
Serial to parallel converter (includes exercises)
All the examples in this site are according Altera recommended coding style. Altera recommends using asynchronous reset at the Flip Flop level.
Xilinx recommends using synchronous reset at the FF level.