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srdjan
srdjan
Associate III
May 27, 2016
Question

MSI calibration and MSICAL register

  • May 27, 2016
  • 3 replies
  • 879 views
Posted on May 27, 2016 at 15:16

Hello,

I'm calibrating my MSI clock when I'm switching frequencies, and I noticed that whenever I write a value to MSITRIM register, MSICAL automatically changes value too. The reference maual states that this is a readonly register, which is factory calibrated, and I would expect that it should have constant value, but it changes based on what I write in the MSITRIM. How is this working? I coudn't find any details in the ref manual.

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    3 replies

    Amel NASRI
    Amel NASRI
    ST Technical Moderator
    May 27, 2016
    Posted on May 27, 2016 at 17:16

    Hi stokic.srdjan,

    This is aligned with MSICAL description in the STM32L4 reference manual (RM0351): 

    These bits are initialized at startup with the factory-programmed MSI calibration trim value. When MSITRIM is written, MSICAL is updated with the sum of MSITRIM and the factory trim value.

    -Mayla-

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    srdjan
    srdjanAuthor
    Associate III
    May 27, 2016
    Posted on May 27, 2016 at 17:23

    This information is missing from RM0038 STM32L1 Reference manual.

    Thank you for your quick reply!

    Amel NASRI
    Amel NASRI
    ST Technical Moderator
    May 30, 2016
    Posted on May 30, 2016 at 19:20

    Hi stokic.srdjan,

    Please note that RM0038 will be updated in order to align MSICAL (and HSICAL) description with the one in RM0351.

    -Mayla-

    To give better visibility on the answered topics, please click on "Best Answer" on the reply which solved your issue or answered your question.
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