MSI calibration and MSICAL register

srdjan · ‎2016-05-27

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.

Amel NASRI · ‎2016-05-27

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 · ‎2016-05-27

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 · ‎2016-05-30

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-

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