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mailmail9113
Visitor II
November 5, 2012
Question

A3G4250D gyro measurements

  • November 5, 2012
  • 4 replies
  • 1651 views
Posted on November 05, 2012 at 18:57

I cannot find a forum for MEMS sensors, so I'm posting here. 

Is anyone using the a3g4250d gyro?  I'm having a problem where I get only one set of measurements after power up.  After that, the measurements do not change (x, y, z, temperature).  I've tried FIFO bypass mode, stream mode, power down/sleep modes, various settings of FIFO_CTRL, etc, and cannot get past this problem.  WHOAMI reads back correctly, and other register values look reasonable.  Does anyone have working example source code?  Are there any errata out there that I'm missing?  

Thanks,

Brian

#a3g4250d-mems-gyro
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    4 replies

    P
    pit
    Visitor II
    January 10, 2013
    Posted on January 10, 2013 at 18:08

    Hello Brian,

    I'm experiencing the exact same problem with the A3G4250D gyro as you describe in your post.

    Could you resolve the issue meanwhile?

    Any hint how you did it would be greatly appreciated!

    Thanks in advance

    Pit

    J
    jtorok
    Visitor II
    August 6, 2013
    Posted on August 06, 2013 at 20:41

    I've seen the same issue as well.  What we have seen is the gyroscope ''locks'' up an I2C bus, and the data freezes.

    What has been interesting, is that when we have three devices on the I2C bus, we never see the issue.  When only two devices, the problem occasionally occurs.  If you lower the temperature of the gyroscope (freeze spray), the problem occurs very frequently.

    It is not on start-up, as I will see readings for about 3 seconds before the data locks up.

    We are still working the issue, but if you have made any breakthroughs and are willing to share, it would be greatly appreciated. 

    G
    gist
    Visitor II
    January 27, 2015
    Posted on January 27, 2015 at 16:41

    Our problem was that the phase locked loop circuit on pin PLLFILT. We had a short between two points so that it didn't work. This caused the issues with only able to read 1 sensor value, then they stayed the same. 

    For reference, my CTRL regs was:

    CTRL1 = 0x0F

    CTRL5 = 0x02

    CTRL[2,4] = 0x0

    Z
    zuo shengting
    Visitor II
    June 17, 2018
    Posted on June 17, 2018 at 06:55

    I also have this problem.... Does anyone know how to fit those regs?

    thanks.

    M
    Miroslav BATEK
    ST Employee
    June 18, 2018
    Posted on June 18, 2018 at 12:12

    zuoshengting

    ‌ what exactly is your problem? Can you share your schematic?

    Z
    zuo shengting
    Visitor II
    June 29, 2018
    Posted on June 29, 2018 at 03:25

    thank you for your reply.

    I bought the steval-MKI125V1, and the schematic is here:

    0690X0000060LUKQA2.png

    Now, I am able to read the angular rate of X,Y,Z, but there is a lot of noise. Here is Z axis data:

    0690X0000060LXSQA2.png

    I really confused. Do I use the wrong way of getting those data? Or these noise is exist truly?

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