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I am wondering why oscillator is configured to internal RC?
I think it is not like that. For bangle 2 32768Hz xtal is used however it is still inaccurate. However when switching to RC (you may try with this line commented out) it becomes much worse so I guess it is what it is. Search this forum, there were some attempts to autoadjust/correct this over time, maybe even some app. It is supposed to be synced periodically when connected to the phone so not the best crystals are used in these smart watches.
fanoush
I bought a Bangle.js 2 half a year ago. One thing that been bothering me is how inaccurate the clock is, drifting a minute over a week. At first I thought the 32768Hz xtal were saved to use pins for something else, but recently saw it is mounted on a picture. Failed to find a schematic.
Now I am wondering why oscillator is configured to internal RC? I know the softdevice can calibrate it to about 250ppm, good enough for BLE with cost of extra power consumption. But seems strange why xtal not used they usually 20ppm if balanced properly.
Anyone knows reason behind it?