Hello, @DaveG! I'll go pinpoint some observations that might help you with your issue:
1. I don't see the IP Digilent provides in your design. In order for Pmod DHB1 to correctly work you should use the IP provided by Digilent. Here is the tutorial for general Digilent IP usage. If you have actually followed the tutorial please tell mention this.
2. The source code files you attached cannot be opened. Could you please provide them so that we could open them?
3. Here you can find a reference project with something similar.
Good luck!
