topic Re: Please let me know what we should do to write values to MCG_C3/MCG_C4 registers. in Kinetis Microcontrollers

Please let me know what we should do to write values to MCG_C3/MCG_C4 registers.

tanaka_shinsuke — Tue, 18 Dec 2018 08:03:14 GMT

Dear Sirs or Madams,

Please let me have a question regarding what we should do to write values to MCG_C3 and MCG_C4 registers.
Concretely speaking, I want to know what the following descriptions shown on K61P256M150SF3RM document mean;
-A value for SCTRIM is loaded during reset from a factory programmed location.(for MCG_C3)
-A value for FCTRIM is loaded during reset from a factory programmed location.(for MCG_C4)
-A value for SCFTRIM is loaded during reset from a factory programmed location.(for MCG_C4)
I now guess that the above descriptions mean as follows;
   1) "factory programmed location" means memory or register addresses like 0x400*_****,
       which are different from MCG_C3 and MCG_C4 addresses 4006_4002h/4006_4003h.
   2) In order to write intended values to MCG_C3 and MCG_C4 registers, we have to
      determine the appropriate values by ourselves and store the pre-determined values
      to "factory programmed location" in advance.
   3) During reset of K61, 32-bit MCU core inside K61 itsef
      executes read access to "factory programmed location" and then
      it writes the values acquired from "factory programmed location" to 4006_4002h/4006_4003h.

Are my above guesses correct?
If they are correct, please let me know the concrete address of "factory programmed location".
If they are incorrect, please let me know what "factory programmed location" actually means
and let me know what we should do to write intended values to MCG_C3 and MCG_C4 registers.

Best regards,
Shinsuke Tanaka

Re: Please let me know what we should do to write values to MCG_C3/MCG_C4 registers.

Robin_Shen — Thu, 20 Dec 2018 03:17:58 GMT

Hi Shinsuke Tanaka,

1) Yes. But we don't know the concrete address of "factory programmed location".

2) No. Usually we use the external debugging tool to operate the trim. Refer: Yes, OSDA can trim the reference of internal clock source!

3) Yes. If default IRC frequency is needed, you don't need to write MCG_C3 and MCG_C4.

Best Regards,

Robin

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Re: Please let me know what we should do to write values to MCG_C3/MCG_C4 registers.

tanaka_shinsuke — Thu, 20 Dec 2018 06:02:19 GMT

Dear Mr.Shen,

I appreciate your rapid response.

And, to deepen my understanding, could you please let me have additional questions?

Q4.

>Manufacturing process yealds to frequency deviation, that is why all MCU devices are factory programmed

>with a trim value in a reserved memory location.

Above description is shown on the Q&A page you referred to.

Does this description mean that

the values for MCG_C3 and MCG_C4 stored on "factory programmed location" are different one by one per K61 chip?

For example, when I have two MK61FX512VMJ15 chips, which I now call SampleA and SampleB, is it possible that

the values for MCG_C3 and MCG_C4 stored on "factory programmed location" of SampleA are different

from those of SampleB?

Best regards,

Shinsuke Tanaka

Re: Please let me know what we should do to write values to MCG_C3/MCG_C4 registers.

Robin_Shen — Wed, 26 Dec 2018 02:28:43 GMT

Does this description mean that the values for MCG_C3 and MCG_C4 stored on "factory programmed location" are different one by one per K61 chip?

Yes