Once you get the ASF_Core thing figured out, here's another library you might want to try. I've gotten my Feather M0 proto down to 30 uA while sleeping.
https://github.com/ee-quipment/ZeroPowerManager
Feather M0 - Sleep Mode - Help needed
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Please be positive and constructive with your questions and comments.
Please be positive and constructive with your questions and comments.