The user memory area - accessible by machine.RTC.memory() -- will now
survive most reboot causes. A power-on reset (also caused by the EN pin on
some boards) will clean the memory. When this happens, the magic number
not found in the user memory will cause initialization.
After other resets (triggered by watchdogs, machine.reset(), ...), the user
is responsible to check and validate the contents of the user area.
This new behaviour can be changed by enabling
MICROPY_HW_RTC_MEM_INIT_ALWAYS: in that case the RTC memory is always
cleared on boot.
Signed-off-by: Thomas Wenrich <twenrich@gmail.com>
78b3fe5689