NRF: Persist RTC offset across reboots #2924
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This section immediately follows the .bss section, and is designed to contain uninitialized variables that should persist across reboots. The section is placed directly after .bss, under the theory that the size of Circuit Python's .bss + .data is bigger than the bootloader's .bss + .data, so there is less likely to be a conflict. Signed-off-by: Sean Cross <sean@xobs.io>
Previously, it was placed following .bss. However, now that there is a new section after .bss, the heap must be moved forward. Signed-off-by: Sean Cross <sean@xobs.io>
Circuit Python supports saving a single word of data across reboots. Previously, this data was placed immediately following the .bss. However, this appeared to not work, as Circuit Python zeroes out the heap when it starts up, and the heap begins immediately after the .bss. Switch to using the new .uninitialized section in order to store this word across resets. Signed-off-by: Sean Cross <sean@xobs.io>
Store the RTC value in the .uninitialized section, but make sure to flank it with some known values. That way we can determine if the RTC value has been initialized, or if it's random uninitialized garbage. As part of this, add a `common_hal_rtc_init()` routine to determine if the value is correct, or reset it to 0 if it is not valid. Signed-off-by: Sean Cross <sean@xobs.io>
Call the new function to set the RTC, or reset it if the offset is not valid. Signed-off-by: Sean Cross <sean@xobs.io>
tannewt
approved these changes
May 18, 2020
|
No, because right now we don't actually power off -- we need to keep Bluetooth running. The plan is to check to see if it's the year 2000, and if so set the current time to the time of import os
import rtc
import time
system_rtc = rtc.RTC()
if system_rtc.datetime.tm_year == 2000:
system_rtc.datetime = time.localtime(os.stat("/code.py")[8]) |
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This patchset introduces a new
.uninitializedlinker section and places the RTC value into this section. It uses sentinal values to determine if the RTC offset is valid.As part of this rework, the
port_saved_wordAPI was reworked to also use a value in this new section.