Is the internal RTC a separate circuit on the STM32 chip, able to continue running somehow when there is a re-start or power loss? Can a small backup battery be attached to the Spark Core for this purpose?
Thanks,
Paul
Hello @PaulRB
The RTC is internal to the STM32 microcontroller. The VBAT pin is used to power the internal RTC (via a battery or a super capacitor). But in its current configuration, its powered by the main 3V3 supply and cannot be kept running on power loss.
If you really want to, you could technically hack your way into the Core and power the VBAT separately.
This is a great question… didn’t even think of this til now.
So would it be a fairly good way to power the Core via Vin with a tiny 150mAh (or as large as you want) lipo to keep the RTC powered, but then to conserve power put the Core to deep sleep via Spark.sleep(SLEEP_MODE_DEEP,60);
http://docs.spark.io/#/firmware/sleep-spark-sleep
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