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JLee.75
JLee.75
Associate
August 24, 2022
Solved

IIS3DWBTR I2C address with SA0 high or low. I didn't see this in the datasheet.

  • August 24, 2022
  • 4 replies
  • 1729 views

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    This topic has been closed for replies.
    Best answer by Tesla DeLorean

    1101010x for SA0=0 (0x6A << 1)

    1101011x for SA0=1 (0x6B << 1)

    4 replies

    Tesla DeLorean
    Tesla DeLoreanBest answer
    Guru
    August 24, 2022

    1101010x for SA0=0 (0x6A << 1)

    1101011x for SA0=1 (0x6B << 1)

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    JLee.75
    JLee.75Author
    Associate
    August 24, 2022

    Thank you, did I miss this in the datasheet?

    Tesla DeLorean
    Tesla DeLorean
    Guru
    August 24, 2022

    The low order bit was mentioned several times, the actual address pattern wasn't, even in things like the timing diagram

    https://github.com/STMicroelectronics/iis3dwb-pid/blob/master/iis3dwb_reg.h

    @Amel NASRI​ can we flag the data sheet issue to the technical writers, thanks

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    Amel NASRI
    Amel NASRI
    ST Technical Moderator
    August 25, 2022

    Hi @Community member​ ,

    I let @Eleon BORLINI​  take care of this request.

    -Amel

    To give better visibility on the answered topics, please click on "Best Answer" on the reply which solved your issue or answered your question.
    Eleon BORLINI
    Eleon BORLINI
    ST Employee
    August 25, 2022

    Hi,

    let me add that, for IIS3DWB, the SPI communication protocol is recommended, especially if the device is configured in 3-axis mode, since the ODR is fixed at 26.67kHz and is quite high for a sensor.

    Anyway, I'll notify this missing info to our technical writers team.

    -Eleon

    Tesla DeLorean
    Tesla DeLorean
    Guru
    August 25, 2022

    Understood, playing devils advocate here.

    Data sheet lacks detail on I2C speed supported too, so 400 KHz, or 1 MHz ?

    A table of anticipated bandwidths may make the I2C vs SPI case more strongly.

    I think @JLee had a different question/thread, where it's a sub-set of functionality, or triggering, that's desired.

    https://www.st.com/resource/en/datasheet/iis3dwb.pdf

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    JLee.75
    JLee.75Author
    Associate
    August 26, 2022

    But as I mentioned in my other post and repeated here, I don't care about getting the data out at high sample rates. I'm just using the interrupts for thresholds and want to use this part because it has a higher bandwidth for detection.

    In I2C mode for the IIS3DWB device the datasheet says it only support single axis mode because I2C is too slow to get the data. I want to use I2C mode to configure either wake up or activity thresholds for all 3 axis and then configure the interrupts to tell me those thresholds were exceeded. I don't need the data.

    So the questions are In I2C mode:

    1. Are all the axes still active?
    2. Can I access all the registers in I2C mode to configure the thresholds for all axes of the device for the interrupts?
    3. Can I effectively get two thresholds for each axis if I use one set of thresholds for wake up configured on INT1 pin and another set of thresholds for activity configured on INT2 pin?

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