Found this peice of code to study.

Trying to understand how to interface to a MIDI interface by starting with some random piece of code you found on the internet is not going to help.

I have not used the MIDI interface, but it looks like an interface with a standardized hardware interface, and a signalling protocol.

To interface to an FPGA I/O pins, you need to determine whether you need logic-level translators. Once you have it interfaced to an FPGA, you need to review the timing diagrams for the protocol and determine whether the interface is synchronous or asynchronous. Once you have that information you can write a state machine for decoding the protocol, and then simulate it in Modelsim to confirm that it works. Once your simulation works, you can interface to a MIDI instrument, and use SignalTap II to trace the hardware interface signals to confirm that they operate like your simulation assumes.

At that point you will have a functional MIDI interface.

Cheers,

Dave