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Original question:

TPS65381A-Q1: CAN WU pin & feature

TCAN1043-Q1: CAN wake up pattern

MDO
Prodigy 110 points
Part Number: TCAN1043-Q1
Other Parts Discussed in Thread: TCAN1043, TCAN1051, TPS65381A-Q1

Hello,

Can you indicate me if CAN wake up pattern is available on all vehicles (car,  tractors...) with CAN bus?

Is it a recent function?

How is it possible to check this for each brand or model vehicle?

Best regards,

MDO

  • 0
    TI__Guru 65932 points
    MDO,

    Are you referring to the dominant - recessive - dominant wake up pattern? This has been defined by ISO11898-2:2016, and has been implemented in CAN transceivers prior to that. All vehicles that have a CAN bus, which is all automotive vehicles, should have the wake up pattern implemented.

    I'm not exactly sure how to check if this is implemented in specific vehicles, but I would just assume it was if they are using a CAN bus. Using an ODB reader, you can access the CAN bus and see the messages to and from different CAN nodes, but this is presented in numerical values and not actual waveforms. There are CAN bus analyzers, but again, you'd have to probe into the CAN bus in the vehicle, which is not an easy task without an ODB port reader.

    Are you interested in learning more about CAN and the wake up function?

    Regards,
  • 0 in reply to Eric Hackett
    Prodigy 110 points
    Thanks Eric for your quick feedback.

    I am well referring to the dominant - recessive - dominant wake up pattern.
    Is it generated just after the vehicle power on?
    Which element/component generate this pattern?

    Best regards,

    MDO
  • 0 in reply to MDO
    TI__Guru 65932 points
    MDO,

    Typically, on vehicle power up a local wake up is used on an intelligent transceiver, or a system basis chip (SBC) which has a CAN transceiver with a power supply and other functions integrated in one package. A high-voltage pin dedicated to wake up is tied to an "ignition" source and is pulled up to battery when the car is started. Then, the more intelligent transceiver or SBC will initiate further system startup by issuing commands from its controller to the rest of the CAN bus. The CAN controller is ultimately what controls the CAN bus and is what will send the CAN bus wake up message.

    The transceiver merely translates the message from the controller to the bus, however more intelligent transceivers and SBCs have built-in functions that help with system initiation.

    Regards,
  • 0
    TI__Intellectual 2090 points

    MDO, 

    Wake Up Pattern functionality is not a recent feature in the automotive CAN market.  It is most commonly used in a system-level sleep mode in order to conserve power when CAN data transfer is not needed.  We see this system-level power-conservative mode being used very often in automotive CAN solutions.  However, not all automotive networks will use this feature in their systems.  There is not a catch-all answer, but most modern CAN transceivers today will support a Wake Up Pattern (WUP) detection.  WUP functionality is not specific to brand or model vehicle, but is specific to the transceivers used in their CAN networks. 

    Specifically, any TI CAN transceiver that supports Standby mode or Sleep mode will be equipped with an integrated receiver capable of processing a Wake Up Pattern.  Such transceivers include the TCAN1042, TCAN1043, and TCAN1044, to name a few.  

    Other transceivers that do not support the Wake Up Pattern usually possess a mode called Silent mode or Listen Only mode instead of Standby mode or Sleep mode.  In these devices, there is no need for a Wake Up function for the device, and so the WUP processing is not implemented.  An example of this type of transceiver is the TCAN1051.

    In short, you will need to know the specific transceivers implemented in the automotive CAN networks in order to ascertain the implementation of WUP functionality.  You will be able to identify the Wake Up functionality for each transceiver by referring to its individual datasheet.  

    What does your specific application look like?  Do you expect to implement system-level wake-up for your own system?

    Best Regards,

    Max Megee

    Transceiver Interface Apps

  • 0 in reply to Max Megee
    Prodigy 110 points

    Dear Eric & Max,

    Thanks for your answers Eric,

    My application is used on tractors but not as OEM device. So it can be used on every tractors with CAN bus and Isobus especially.
    Some of brands, as Fendt, provides power supply to the device when the tractor is powered off.
    Thus, my device is in low power mode during this state.
    That's why I need to have wake up function and especially by using CAN bus. I can't unfortunately use Ignition signal.
    So, my device uses TPS65381A-Q1 and I plan to use TCAN1042 as adviced in another post.

    So, I wander how to know if this or that tractor's model has which type of transceivers...

    Best regards,
    MDO

  • 0 in reply to MDO
    TI__Guru 65932 points
    MDO,

    Knowing when this model of tractor was developed will help, but also knowing how the CAN nodes are used in the tractor will help as well. That is, how often they are active vs. inactive, and if certain portions of the tractor turn of during operation while others stay on. This would indicate that there are already wake signals on the bus being used to wake up other nodes.

    However, more than likely there are CAN wake signals present on the bus. Is there any way to information on sections of the tractor's schematics? Or possibly a part of the tractor you are able to analyze with a logic analyzer or oscilloscope?

    Regards,
  • 0 in reply to Eric Hackett
    Prodigy 110 points

    Eric,

    Unfortunetay, our device is meant to be used with several models of tractors and we can't check bus CAN of each of them.

    I'll to check with Isobus ISO 11783 if a tractor equiped with Isobus devices induces to have CAN wake signals.

    Fortunately, we have back up solution based on the TCAN1051.

    Regards,

    MDO

  • 0 in reply to MDO
    TI__Guru 65932 points

    MDO,

    The CAN wake signals may just look like typical CAN messages, so this may be hard to determine even looking at the messages on the ISObus. 

    Given what you've told me about the Fendt tractors still having some kind of function even when the tractor is powered off, I would assume that wake-up messages are available on the CAN bus, because other CAN nodes will need to be brought to an active state. Also, depending on the data rate, CAN traffic can wake up the TCAN1043 as well.

    Regards,