In the lowest power state it's the only clock we have which is usable.LPOSC is not meant to be precise, just to have a low power profile or to be used as a last resort clock.
And we need to use that to keep the Always-On Timer ticking along, to keep track of time for when it returns to a more operational state, if not wanting to use an external battery backed-up RTC.
On boards where a buck-boost or linear regulator delivers 3V3 the effects of voltage on LPOSC should be minimal unless it is far more variable than anticipated. Temperature is however quite often outside of the user's control. Unfortunately the datasheet doesn't quantify the effect of either voltage nor temperature.However, the LPOSC frequency varies with voltage and temperature, so fine-tuning is only useful in systems with stable voltage and temperature.
If the LPOSC is too variable to be useful then I am not sure what usefulness the Always-On Timer has in the situations where it would be most desirable for it to be usable.
For keeping track of time in the lowest power mode it would not seem to be fit for that purpose.
Other than doing that in the lowest power mode I am not sure what usefulness or purpose the Always-On Timer has. When run from XOSC it has only millisecond resolution while other equally accessible and usable clocks have microsecond resolution and can track time far beyond anything ever needed.
The only real use I can see for most users is in keeping track of time in lowest power mode, providing RTC functionality without needing an external RTC. But I'll accept I may have only imagined it would be more useful than it is for how I had hoped to use it. Getting LPOSC calibrated was just the first steps towards determining whether it is usable or isn't, quantifying what it's usefulness would be.
Yes, I had considered that but didn't want to spend the time understanding this frequency counter, how to configure and use it, when there seemed to be alternative, simpler and easier, ways to achieve the same thing.The LPOSC clock can also be sent to the frequency counter for calibration
I might consider that a future adventure and I will take a look in the datasheet to see if it's worth a detour that way while all this is fresh in my mind.
Statistics: Posted by hippy — Thu Nov 14, 2024 5:35 pm