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TCAN1162-Q1: Trouble to wakeup CAN transceiver

Anisha George
Prodigy 10 points
Part Number: TCAN1162-Q1

Tool/software:

We are facing problems with the waking up of TCAN1162 transceiver. We managed to put it in to sleep but couldn't wake up using a CAN WUP frame. We also have some confusions on the states of this transceiver. We are following this diagram.

 

These are our assumptions.

  1. The transceiver will enter into normal mode if the supply voltage is greater than under voltage limit and the nSPL pin is high
  2. When nSLP is low the transceiver enters standby mode
  3. When nSLP is low for more than tSLP, the transceiver is in sleep mode.

 

Our confusion is what is the difference in standby mode and sleep mode? If we keep the nSLP low, does it immediately go to standby mode and if we keep the nSLP pin low for more than tSLP, does it enter to sleep automatically? Or do we need to apply a pulse to enter standby mode? Is it possible to keep the transceiver in standby mode for a period of time?

 

We tried to wake up the transceiver using a WUP CAN frame, but it did not wake up the transceiver. Can you please suggest a CAN message frame to check this from our side? We are using CAN FD 500kbps.

  • 0
    TI__Mastermind 28550 points

    Hi Anisha,

    Standby mode is an intermediate mode between sleep mode and normal mode, it's not the lowest mode because INH is ON in standby mode. After initial power up, the device will enter standby mode first. POR is counted as a wake event so it won't immediately go to sleep mode after initial power up. If you pull nSLP to low (or left floating) in normal mode, the device will first enter standby mode, then enter sleep mode after nSLP = low for t > tSLP.

    Basically any CAN frame can wake up the device, do you mean sending a CAN frame doesn't bring INH to high?

    Regards,

    Sean

  • 0 in reply to Sean Guo
    Prodigy 10 points

    Sending a CAN frame doesnt bring INH to high . Can you share any example of CAN frame that work? We are using CAN FD 500kbps. Is there any sequence it expects ?

  • 0 in reply to Anisha George
    Prodigy 10 points

    This is an excerpt from Data Sheet - What is the wakeup pattern referred here

  • 0 in reply to Anisha George
    TI__Mastermind 28550 points

    Hi Anisha,

    A valid WUP is a dominant + recessive + dominant pattern, each bit time should be at least tWK_FILTER. Please find a more detailed description in 7.4.1.3.1

    Can you check if the duration of each state meet this requirement?

    Regards,

    Sean

  • 0 in reply to Sean Guo
    Prodigy 10 points

    Is the highlighted statement true? Does the chip wakeup with any CAN message and make the INH high?  Currently we don't have facility to check the timing duration of CAN Message. Is it possible to share an example of a sleep wakeup feature?

  • 0 in reply to Anisha George
    TI__Guru 52116 points

    Hi Anisha,

    Sean is currently OoO at the moment. Any valid WUP wakes the device similar to the mentioned 7.4.1.3.1 of the data sheet. This ensures unintentional wake ups do not occur, thanks.

    Best Regards,

    Michael.

  • 0 in reply to Michael Ikwuyum
    TI__Guru 53575 points

    Hi Anisha,

    Here is an example of a CAN frame acting as a WUP for a CAN transceiver. The wake filter for a WUP is defined to be a maximum of 1.8us for this device. With a data rate of 500kbps, the bit time of 2us satisfies this requirement for the filter. Because a CAN frame is guaranteed to have at least one set of transitions that include a dominant-recessive-dominant pattern this means any CAN frame at this data rate will include a WUP. 

    In this waveform we can see that the INH signal only goes high after the second dominant state on the CAN bus (high period on CANH). The added delay includes the additional 1.8us twk_filter as well as the mode change delay (up to 50us) from where the WUP was recognized. 

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

    Regards,
    Eric Schott

  • 0
    Prodigy 10 points

    Hi Eric,

    Thank you for the response.

    We are using Vector Canoe tool and do not have any function generators to generate message from waveform patterns.
    That is the reason we have been asking for a while for a sample CAN message frame .Can you please provide an example message id to be sent while using CAN FD 500kbps?

  • 0 in reply to Eric Schott1
    Prodigy 10 points

    Hi Eric,

    Thank you for the response.

    We are using Vector Canoe tool and do not have any function generators to generate message from waveform patterns.
    That is the reason we have been asking for a while for a sample CAN message frame .Can you please provide an example message id to be sent while using CAN FD 500kbps?

  • 0 in reply to Anisha George
    TI__Guru 53575 points

    Hi Anisha,

    A waveform generator should not be needed to evaluate here. Any CAN message ID at 500kbps will act as a WUP and wake the device. The example above is a CAN frame at 500kbps. The ID and data can be seen in the terminal on the right side of the first screenshot. 

    Regards,
    Eric Schott