In an I3C Hub, the SMBus Agent is a specialized functional unit associated with each downstream (Target) port. It acts as a bridge that allows legacy SMBus devices to coexist with modern MIPI I3C networks by managing the specific timing and protocol requirements of SMBus that differ from standard I3C. 

This blog introduces how to Testing the I3C Hub SMBus Agent based on the Tower I3C Host Adapter:

Testing the I3C Hub SMBus Agent based on the Tower I3C Host Adapter