I’m working on a prototype which needs to wake-up once every few minutes to sample sensors and go back to sleep. I aggregate a bunch of data and send it to the cloud later. Basically, I want to timestamp my readings if the wakeup source timer is has sufficient precision(based on the external RTC Xtal).
I have a few questions,
What timer is used in the STM32 to wakeup from DeepSleep? Digging through the STM32 datasheet, I realize there is a IWDG and a RTC Alarm which can wake the chip up. Which is used in the Sleep() routine specified in the Particle OS?
Is the IWDG clocked from the same 32.768KHz RTC crystal?