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Original question:

TCAN1145-Q1: Selective wake up support

TCAN1145-Q1: Selective Wakeup on CAN FD message.

Mukthabai Karajagi
Prodigy 10 points
Part Number: TCAN1145-Q1

Hello TI Team,

I'd like to confirm TCAN1145-Q1's capability of wake-up behavior.

As per the TCAN1145-Q1 Datasheet it is evident that the Wake up Frame(WUF) is valid if the received frame is Classical CAN Frame.

Hence I would like to confirm if the Selective wakeup is possible for range of Extended FD CAN Frames.

And also I wanted to know if there any other TI transceivers which support Selective wakeup on Extended FD CAN Frames.

Thank you.

Regards,

Muktha Karajagi

  • 0
    TI__Guru 53555 points

    Hi Muktha,

    Thanks for bringing your question to E2E. 

    Selective wake is compatible with the CAN FD frame format, but WUFs can not switch data rates in the middle of a frame like most CAN FD frames will do. It is possible to maintain the CAN FD format without changing data rates by ensuring that the bit rate switch (BRS) field is disabled in the frame before it is transmitted. 

    The selective wake function is defined in the ISO 11898-2 CAN standard to only use wake up frames (WUF) with a fixed data rate. This drastically reduces the complexity and therefore cost of the supporting transceiver. The capability of using an FD frame for selective wake would also provide no benefit to the system as the ID of the WUF (the part of the frame that is filtered for WUF recognition) is transmitted at arbitration rates and thus sees no benefit from the FD data rate. For these reasons I don't expect that any future selective wake capable transceivers will change in order to support wake via CAN FD frames with the BRS active. 

    Let me know if you have any more questions. 

    Regards, 
    Eric Schott