tree 715f632f06406a43cf775935c8e2d74571622daa
parent 53befa6f414fb4944d5d38ae11e21c9a8e9f65b2
author Jerzy Kasenberg <jerzy.kasenberg@gmail.com> 1605739752 +0100
committer kasjer <kasjer@users.noreply.github.com> 1630045560 +0200

stm32: Add tickless sleep based on RTC

RTC is available with very similar functionality
across STM32F0, STM32F4, STM32F7, STM32L0, STM32L1, STM32L4 STM32WB55.

STM32F1 had RTC base tickless sleep (where RTC is completely different).

This adds possibility to have tickless sleep based on RTC instead of
ARM tick clock.

OS ticks based on RTC are limited to 128, 256, 512, 1024 ticks per second.
If RTC is powered by battery RTC also propagated hardware kept time up
to OS at start.

RTC Alarm A interrupt is used as tick source.