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TCAN1145-Q1: CAN Transceiver "TCAN1145-Q1" take long time to wakeup

Hossam Afifi
Prodigy 50 points
Part Number: TCAN1145-Q1

Tool/software:

Hello Team,

I'm using  Can Transceiver  "TCAN1145-Q1"  and configure speed of CAN to be 500K and CANFD 2000K. When using this TCAN1145-Q1 in Partial Network and send "NM" message - sleep request to ECU "PNC not valid " -, Can Transceiver is going to sleep mode and INH pin set to low. But when we set PNC correctly from CANOE (send valid 'NM' message to) the CAN transceiver. It does wakeup and INH pin is set to high after 10s ('NM' message has to be sent repetitively 10 times to wakeup. 1 'NM' message every 1s) . I need to know why do I need to wait 10s to set INH pin High and wakeup the CAN transceiver ? and how to fix this ?

Note:

- We send NM message through CAN not CAN FD 

- attached below the configuration of selective wakeup. 'Selective_wakeup_Config' function is called to sleep the CAN transceiver  

 

Thanks

Hossam Afifi

  • +1
    TI__Guru 53555 points

    Hi Hossam,

    When TCAN1145 is in sleep mode with partial networking enabled, it has two states - one with only the internal low power receiver enabled where the device is monitoring the bus for a wake up pattern (WUP) and one with the partial networking receiver active monitoring the bus and decoding CAN frames for a wake up frame.(WUF). When the CAN bus is idle, the be in this first state with only the low power receiver active. When a WUP is detected (any CAN activity will satisfy this) the transceiver will switch into the second active listening mode and decode all incoming classic CAN frames. However, if the bus remains idle for longer than tSILENCE (0.6 - 1.2 seconds), the device will switch back into the low power WUP detection mode. 

    In your test because you are sending CAN frames at an interval longer than tSILENC, it is possible that the device is never in an active listening mode when the CAN frames are sent. Each frame will be recognized as a WUP and the device will time out back into a low power listening state before the next frame as transmitted. In order to properly wake the device, the WUF will need to be sent within tSILENCE(min) of an earlier CAN frame to ensure the device is in active selective wake listing mode. 

    Let me know if this is clear and if you have any more questions. 

    Regards, 
    Eric Schott 

  • 0 in reply to Eric Schott1
    Prodigy 50 points

    Hi Eric,

    Thanks for your reply.

    Is there a way to disable tSILENCE so that the time between WUP and WUF can be extended further?

    Thanks

    Hossam Afifi

  • 0 in reply to Hossam Afifi
    TI__Guru 53555 points

    Hi Hossam,

    Unfortunately the tSILENCE timer cannot be disabled. This timer is used to control the power state of the device while in sleep mode so it is important to the function of partial networking to minimize the time that the device spends in an elevated power state when on an idle bus.

    In most CAN systems this will not be an issue due to the way that CAN controllers will auto-retransmit CAN frames that are not met by an ACK. This means that the two CAN frames will likely appear right after one another - a much shorter time than the 600ms allotted by tSILENCE.

    Regards, 
    Eric Schott