COMMUNICATIONS BUS WITH ISOLATION CIRCUIT TO OPERATE ONE CIRCUIT DOMAIN WHILE ANOTHER IS DEACTIVE

Aspects are directed to systems in which control node communicates through a peripheral-side wired communications bus for data communications with other bus-coupled nodes. The control node acts as a master with a main-circuit domain during an initialization mode and when the main-circuit domain is deactivated, and acts as a slave, after completion of the initialization mode and when the main-circuit domain is not deactivated. An isolation circuit is used to isolate the main-circuit domain from the control node and, while the main-circuit domain is deactivated, to facilitate communications over the peripheral-side wired communications bus between the control node and another node connected to the peripheral-side wired communications bus.