Devices with RTC backup-batteries have been shown (very rarely) to have
incorrect RTC prescaler values. Such incorrect values mean the RTC counts
fast or slow, and will be wrong forever if the power/backup-battery is
always present.
This commit detects such a state at start up (hard reset) and corrects it
by reconfiguring the RTC prescaler values.
Signed-off-by: Damien George <damien@micropython.org>
Prior to this commit, the ADC calibration code was never executing because
ADVREGEN bit was set making the CR register always non-zero.
This commit changes the logic so that ADC calibration is always run when
the ADC is disabled and an ADC channel is initialised. It also uses the LL
API functions to do the calibration, to make sure it is done correctly on
each MCU variant.
Signed-off-by: Damien George <damien@micropython.org>
