title: How to use multiple Verilog files in Quartus
body: <p>I am learning Verilog with Altera's (now Intel) Quartus Prime development s/w and a DE0_Nano Cyclone IV dev board. I have the Charles Roth et al book "Digital Systems Design Using Verilog" which seems very good at the Verilog module level. I have also looked through a number of on line tutorials and I have a project working using a single Verilog file which is fine as far as it goes.</p>
  
  <p>What I am missing and cannot find any guidance on is how to split a project into multiple hierarchical Verilog source files. I only want the hierarchy's top level file with the top level module instantiated in the Quartus project's .bdf file (the top level of the project drawn like a circuit).</p>
  
  <p>Anyone any ideas how to do this? I presume simply <em>including</em> the lower level files in the top level Verilog file (via `include directive) is not the best way to do it. (Although do doubt it would work)</p>
  
  <p>Help appreciated,
  John</p>