KL82 RTC load capacitance setting

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KL82 RTC load capacitance setting

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Contributor II

I have this crystal as my rtc timer clock: NX2012SA-32.768K-STD-MUB-1 NDK | Crystals, Oscillators, Resonators | DigiKey  for a KL82 micro controller. Any the RTC is drifting a lot. So I looked into the datasheets and found load capacitance setting on page 1299 of the manual:

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cause there is no 12.5pf setting, should I enable SC16P bit or should I enable both SC8P and SC4P?

What's the meaning of enable the additional load? When I set these bits, do they enable the cap inside mcu or just tell the mcu we have a crystal which has this amount of load capacitance?

Thank you very in advance.

Best,

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Contributor II

46.4.1.1 Oscillator control
The 32.768 kHz crystal oscillator is disabled at VBAT POR and must be enabled by
software. After enabling the cystal oscillator, wait the oscillator startup time before
setting SR[TCE] or using the oscillator clock external to the RTC.
The crystal oscillator includes tunable capacitors that can be configured by software. Do
not change the capacitance unless the oscillator is disabled.

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