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TCAN1145-Q1: Transmit Delay Compensation and Mechanism of secondary sample points

Ryker She
Expert 7620 points

Part Number: TCAN1145-Q1
Other Parts Discussed in Thread: TCAN4550-Q1

Tool/software:

Hi expert,

Does the TCAN1145 have a mechanism to transmit time delay compensation (TDC) and a secondary sample point? Currently the measured CANFD data segment sampling point is lower than the setting and R&D wants to know if this is related to the configuration of TCAN1145 and if this can be resolved by TCAN1145? Thanks.

  • Issue background: The measured CANFD segment sampling point is always lower than the software configured sample point value, which cannot meet customer request. The data segment sampling point requirement for the CANFD network is to meet the [78%, 82%] interval. The actual sample point will be lower than 78%.

Best Regards,

Ryker

  • 0
    TI__Mastermind 31980 points

    Hi Ryker,

    No, this is not a mechanism on the CAN transceiver. They need to configure that on the CAN controller.

    Regards,

    Sean

  • 0 in reply to Sean Guo
    TI__Expert 7620 points

    Hi Sean,

    So all CAN transceiver don't integrate transmit time delay compensation (TDC) and secondary sample point (SSP)? Customer has configurate TDC and SSP in MCU, customer tested the sample point rate of the output port configured on the MCU side, within the allowed range. But the CANFD segment sampling point in CAN transceiver is always lower than the software configured sample point value. Do we have some suggestion to solve this issue? Customer is testing competitor devices and confirm competitor's performance. Thanks.

    Best Regards,

    Ryker

  • 0 in reply to Ryker She
    TI__Mastermind 31980 points

    Hi Ryker,

    Sampling point is not controlled by CAN transceiver, it is a mechanism totally handled by CAN controller. The CAN transceiver is simply translating digital signal to analog differential signals, and vice versa. So that's not something we can do on the transceiver side.

    Please let them contact their CAN controller supplier directly. Here is a software guidance from TCAN4550-Q1 for their reference.

    https://www.ti.com/lit/ug/sllu270/sllu270.pdf

    Regards,

    Sean

  • 0 in reply to Sean Guo
    TI__Expert 7620 points

    Hi Sean,

    Thanks for your information. What kind of parameter would influence sample point in CAN controller? Customer has involved CAN controller (NXP MCU), but NXP pass the buck to CAN transceiver. So I want to fight back with detailed proof. Thanks.

    Best Regards,

    Ryker

  • 0 in reply to Ryker She
    TI__Mastermind 31980 points

    Hi Ryker,

    You do not need any proof, it is a common knowledge about CAN. Sample point is a phrase from CAN protocol layer, any protocol layer configuration is not related to a CAN transceiver. Our transceiver only implement physical layer. Let them read ISO11898:1 and ISO11898:2 if they don't believe. Or a simpler way, let them read through our CAN transceiver's datasheet, or any other competitor's, they won't find any instruction to configure sample point. That's not something physically can be handled by the CAN transceiver. The TCAN4550-Q1 software guidance I mentioned above is a good resource for understanding CAN controller, or they can refer to NXP's CAN controller user's manual.

    Your question is also not something I would answer, I'm not supporting NXP's MCU, please let them contact NXP directly.

    Regards,

    Sean