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DRV8899-Q1: SPI timing

Youhei Miyaoka
Expert 3995 points
Part Number: DRV8899-Q1

Tool/software:

Hi team,

My customer are currently doing some SPI Timing measurements on the EVM and they don’t see any SPI Timing diagrams for reference in the latest datasheet.

Could you provide the SPI timing diagram?

Regards,

Youhei MIYAOKA

  • 0
    TI__Mastermind 44615 points

    Hi Miyaoka-san,

    Please use the below diagram for reference. Some of the labeling may include an additional letter "S" compared to the names in the table. Thank you.

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    TI__Expert 3995 points

    Hi Murugavel,

    They want to confirm one item for the SPI timing measurements that I am doing with the DRV8899-Q1EVM.

    According to the datasheet, tdis(nSCS) the expected nominal measured value is 10ns. (No minimum or Maximum)

    They’ve tried to take multiple measurements following the SPI timing diagram you’ve provided for this measurement, but they cannot get any value close to 10ns, the nominal value.

    The bottom waveform is the closest waveform they can capture, but they are still getting 11.8us, instead of anything close to 10ns.

    Could you please let me know if there is a specific method of capturing this waveform?

    Regards,

    Youhei MIYAOKA

  • +1 in reply to Youhei Miyaoka
    TI__Mastermind 44615 points

    Hi Miyaoka-san,

    Youhei Miyaoka said:
    According to the datasheet, tdis(nSCS) the expected nominal measured value is 10ns. (No minimum or Maximum)

    How did the customer measure SDO becoming high impedance? Please describe this process. And why is the customer wanting to measure this time? Are they having another SPI device on the same bus and seeing issues? 

    Youhei Miyaoka said:
    Could you please let me know if there is a specific method of capturing this waveform?

    Our tests are based on internal operating modes or the SPI and it is not externally tested. I'm not sure if there is a way to measure this parameter externally because we need to differentiate between a push-pull output vs. floating output for Hi-Z. Thanks.

    Regards, Murugavel  

  • 0 in reply to Murugavel4637
    TI__Expert 3995 points

    Hi Murugavel,

    Thank you. They understood your comments. They have other question on SPI timing. Could you help them please.

    They are taking the t(HI_nSCS) measurement and getting nSCS high time of 840us.

    According to the datasheet, the maximum minimum time is 2us.

    If their understand correctly, 840us should not be an issue since the spec says the minimum high time is 2us max, however could you please confirm if it is acceptable.

    Regards,

    Youhei MIYAOKA

  • +1 in reply to Youhei Miyaoka
    TI__Mastermind 44615 points

    Hi Miyaoka-san,

    Youhei Miyaoka said:
    According to the datasheet, the maximum minimum time is 2us.

    Unfortunately this is a typo. the minimum high time min is 2us. There is no max limit to this specification. Customer application should be good with 840us, no issues. Thank you.

    Regards, Murugavel