What is a Sleep Mode / Wake-up?

To reduce the system’s power consumption, a CAN-device may be set into sleep mode without any internal activity and with disconnected bus drivers. The sleep mode is finished with a wake-up by any bus activity or by internal conditions of the system. On wake-up, the internal activity is restarted, although the transfer layer will be waiting for the system’s oscillator to stabilize and it will then wait until it has synchronized itself to the bus activity (by checking for eleven consecutive ’recessive’ bits) before the bus drivers are set to “on-bus” again.

In order to wake up other nodes of the system, which are in sleep-mode, a special wake-up message with the dedicated, lowest possible IDENTIFIER (rrr rrrd rrrr; r = ’recessive’ d = ’dominant’) maybe used.