By design, at wake up from deepsleep, the RTC timer will be reset, but
the data stored in RTC memory will not [1]. Therefore, we have to adjust
delta in RTC memory before going into deepsleep to get almost correct
time after waking up.
[1] http://bbs.espressif.com/viewtopic.php?t=1184#p4082
Use the machine.deepsleep() function to enter the sleep mode. Use the
RTC to configure the alarm to wake the device.
Basic use is the following:
import machine
# configure RTC's ALARM0 to wake device from deep sleep
rtc = machine.RTC()
rtc.irq(trigger=rtc.ALARM0, wake=machine.DEEPSLEEP)
# do other things
# ...
# set ALARM0's alarm to wake after 10 seconds
rtc.alarm(rtc.ALARM0, 10000)
# enter deep-sleep state (system is reset upon waking)
machine.deepsleep()
To detect if the system woke from a deep sleep use:
if machine.reset_cause() == machine.DEEPSLEEP_RESET:
print('woke from deep sleep')
