CCS/RM44L920: how to diagnostic oscillator shift?

Hello,

There are multiple ways to detect an oscillator frequency shift. The question is about how much of a shift can actually be detected accurately. The OSCIN frequency gets "scaled" by the PLL and this output frequency is "measured" with respect to an internal low-power-oscillator (HF LPO) clock source as a reference clock input to the Dual-Clock-Comparator (DCC). However, this method relies on the HF LPO being more accurate than the oscillator, which is typically not true. The clock monitor on-chip is a gross loss-of-clock detector with low-, and high-frequency thresholds that are 1/4th and 4x the HF LPO frequency.

The main oscillator is expected to be the most accurate clock source on the microcontroller.

Regards,
Sunil