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DRV8718-Q1: DRV8718-Q1 SPI issue

Kevin Zeng
Prodigy 10 points

Part Number: DRV8718-Q1

Hi Team,

I have a question regarding the DRV8718-Q1.

I've connected an MCU to one DRV8718 chip via SPI. The SPI configuration is: MSB first, 1MHz, CPOL=0, CPHA=1.

I'm trying to read the DRV8718's status register, but the data from the 8718 appears abnormal. I've specifically measured with an oscilloscope and observed the following data:

  • When DRV8718 SDI receives 0x4000, SDO outputs 0xe040
  • When DRV8718 SDI receives 0x4500, SDO outputs 0xe045
  • When DRV8718 SDI receives 0x4600, SDO outputs 0xe046

The datasheet shows the SDO data format, but my actual test data format is completely inconsistent with the datasheet specifications. What could be causing this situation?

image.png

  • 0
    TI__Mastermind 34525 points

    Hello, we have received your case and the investigation will take some time. Thank you for your patience.

  • +1 回复 Eirwen
    TI__Mastermind 34525 points
    Kevin Zeng 说：
    The datasheet shows the SDO data format, but my actual test data format is completely inconsistent with the datasheet specifications. What could be causing this situation?

    Please share the SPI transaction captures either with a 4-channel oscilloscope or a protocol analyzer showing nSCS, SCL, SDI and SDO simultaneously for debug. See below example of a proper SPI transaction for a similar SPI driver. 

    Kevin Zeng 说：
    The datasheet shows the SDO data format, but my actual test data format is completely inconsistent with the datasheet specifications. What could be causing this situation?

    It is likely a protocol issue. We can debug this with the captures.

  • 0 回复 Eirwen
    TI__Prodigy 10 points

    Hi Eirwen,

    The data received by the MCU side is not the expected value according to the specification. As shown in the figure below: When MCU SDO sends out 0x4600, the MCU SDI receives 0xE046 in return.

  • 0 回复 Kevin Zeng
    TI__Mastermind 34525 points

    Thanks for the capture. Yes, the SDO does not look like the expected value. Not sure what is causing this issue in your HW. The SCLK, nSCS, SDI looks correct. Do you have any other device connected to the same SPI bus? Have you tried with another DRV8718-Q1 device?

    We tried with our DRV8718-Q1EVM and captured with the same transaction multiple times. We did not observe any problem, always got the expected value. See below. Do you have one of our DRV8718-Q1EVMs for comparison?