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Nic400: Create Simple mux instead of arbiter between multiple Initiators.

I have a design with multiple communication interfaces connected to nic400 via either AXI4 or AHBLite and accessing the same set of targets.

Only one interface is guaranteed to be operational on PCB(shared IO pins)

How do I use this knowledge to ensure that Instead of implementing an arbiter between the 3 Initiators and their corresponding targets, NIC400 implements a simple mux with the mux select controlled via the toplevel IO  mux select pins

  • Unfortunately the simple answer is that you cannot. The NIC-400 is an AXI based interconnect with arbitration logic at each destination point to decide which of competing requests to access a target are allowed. There isn't any way to remove this arbitration logic and replace it with a simple MUX.

    However if you know for a fact that only one of the transaction sources will  be active at any one time, the arbitration logic won't be active, so you wouldn't then see any functional penalty in having it there, other than the additional gates you won't be using.

    But if you must avoid having this arbitration logic you would need to implement all the required switching external to the NIC-400, making sure that the switching between sources takes into account any outstanding transactions completing. Not trivial logic !