External controller accesses

Designing the interface is not that hard.

You need to use a custom component to connect to sopc modules, but in most cases this could be a simple _hw.tcl file which exposes Avalon MM interface signals. I attached a sample.

Inside sopc builder this is seen as an Avalon MM master and you can directly connect it to onchip ram or any other Av MM slave; while outside of sopc you may need to provide some extra glue logic to comply with your processor external port.

This is straighforward if this is the only MM master inside sopc system; instead, if you have Nios or other masters on the Avalon bus, you must be aware of bus arbitration and manage the required signals.