@lukasmaximus Thanks so much for your reply! Sorry I missed it. I found the Arduino sample and confirmed it works. Somehow I had been led to believe from issues on Github that it was only supported on Fire, but the battery sample works on my M5 Basic (black).

I know we can’t read the charge level on the M5 core, but is there any way to detect if the power source is battery vs USB? Even adding some custom circuit?