1. A doorbell system comprising a system device that includes: a plurality of flag registers, each having a corresponding flag register address, and each having a plurality of flag entries for storing status/error information associated with the system device; a flag scan controller configured to monitor the flag registers, and activate a doorbell request upon detecting that one or more of the flag entries of a flag register is asserted; and a doorbell generator configured to receive the activated doorbell request, and in response, route the flag entries and the flag register address of the flag register as a doorbell command.