open-source-silicon.dev

while doing   digital design ,  can i connect the input and output pins of user module directly  to GPIO of user wrapper?  In what cases should I use wishbone interface? Also, Am I  allowed  to  modify  user wrapper?

yes, you can. Look at the example project for how things are wired up.

wishbone is for when you want the cpu to interact with your design in some way, for example process some data or configure

there is a bug in the management core at the moment that limits wishbone address from 0x3000_0000 to 0x3010_0000, so be aware of that

yes you can modify user_project_wrapper (you have to, to add your design and wire it)

but you can't add anything in there that needs standard cells, only wires

so even when i  dont need  wishbone interfcae, iam not supposed to  remove wishbone from user wrapper?

No. Pins should stay there. There is requirements list specified in caravel, it includes all pins, names, etc