Physical Layer - CAN System Engineering - page 109

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Fig. 2.49 ECU modes for partial network applications

• A compare unit

During selective wake mode, this unit is active and monitors the CAN communica-
tion like a watchdog. If a dedicated CAN frame is observed, the transceiver wakes
up the ECU. These kinds of transceivers have now two modes in the so-called low-
power mode:

• Sleep mode
• Selective wake mode

In sleep mode, the current consumption is reduced to a minimum and all functions
in the ECU are disabled. Every message on the bus wakes up the transceiver and
the ECU.
In selective wake mode, the current consumption is also low, but the WUF detec-
tion unit is active and monitors the bus. All other functions are disabled. With the
dedicated WUF, the transceiver and the ECU will be woken up.
In Fig. 2.49 , the ECU modes with this new implementation are demonstrated.