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  • TI Thinks Resolved

ISO7331-Q1: Data mismatch between pin 5 and pin 12

Part Number: ISO7331-Q1

Hello,

There is a data transfer error issue. I checked the waveform at pins which are pin 3, pin 4, pin 5 and pin 12.

Pin 3(yellow) is CS signal from MPU. Pin 4(blue) is CLK of SPI. Pin 5(purple) is DATA out of SPI. PIN12(green) is ADC DATA of SPI.

Pin 5(ch3) and pin 12(Ch4) should be almost identical but the second bit of data became mismatch. This waveform is probed ISO7331 pins.

Why this kind of thing happens?

Best regards,

Toshihiro Watanabe

  • Hi Toshihiro-san,

    Thank you for sharing the details and waveform regarding the issue observed. Instead of pin3 (CS) & pin4 (SCLK), could you please share me a waveform with VCC1, VCC2 along with pin5 & pin12? All four waveform in one scope capture. It is okay if GND1 & GND2 get shorted while capturing the waveform, it doesn't cause any issue or error. Thanks.


    Regards,
    Koteshwar Rao
  • In reply to Koteshwar Rao:

    Hello Rao-san,
    Thank you four your feedback. I will ask to capture this but It may need time to capture because all next week is holiday in Japan. Meanwhile I will try to measure the same test by using single chip, not using system.
    Best regards,
    Toshihiro Watanabe
  • In reply to Toshihiro Watanabe:

    Hi Toshihiro-san,

    Sure, testing the same sample or new sample separately for such inputs would also help us understand if there is any problem with device though we don't expect it. I will wait for customer or you to test the device and capture all 4 waveform so that we know the supply is not the one causing the issue. Thanks.


    Regards,
    Koteshwar Rao
  • In reply to Koteshwar Rao:

    Hello,
    I checked this issue. The root cause seems to hazard the timing spec which enable-to-high output delay.
    I think this issue will be solved if 23us is waited to send data.
    Best regards
    Toshihiro Watanabe

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