One example relates to a device that includes an activity monitor. The activity monitor includes a bus interface having inputs coupled to receive signals from a bus and having outputs coupled to provide signals to an other device. The activity monitor monitors the bus for a message directed to a predefined address that is associated with the other device in response to detecting that the other device is a low power sleep mode, the activity monitor outputs the predefined address to the other device to enable the other device to capture the predefined address, via the bus interface, in response to the monitored address matching the predefined address that is associated with the other device.