LPC11Cx2/Cx4 IRC, increase precision by IRCCTRL TRIM

[arnepagel]

I am considering to use the IRC (Internal RC Oscillator), but the 1% Tolerance does not meet my requirements.

In the system, we have one master witch has a more accurate crystal clock.

The Idea is to use time stamps from this master to adjust the IRC of the LPC11C24,

by changing the TRIM Value in the IRCCTL Register.

But the Documentation of the Trim Value is not very precise.

I understand that there is a factory value written to that Bitfield during startup, but it is not indicated,

what is the typical influence of the Trim Value to the RC oscillator's Output Frequency.

Also it would be interesting, if the maximums of this register are already used during factory programming,

means if there would be some room for further adjusting the Frequency, typically.

best regards
  Arne

[kerryzhou]

Hi Arne Pagel,

     Normally, the internal IRC is really not very precise,  about the detail TRIM method, we also don't have it.

    So, if you want to get the more preciser clock, we suggest you use the external crystal instead of the internal IRC, it will be more easier and stable.

Wish it helps you!

If you still have question, please contact me!

Have a great day,
Kerry

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