How in the deuce can I measure the voltage of an attached LiPo battery? There is nothing in the [Hookup Guide
On that note what is the correct pin name/number for VBAT or VUSB? When I try either of those in the arduino ide I get a compile error:
#define BATT_PIN VBAT
gives the error
error: 'VBAT' was not declared in this scope
](https://learn.sparkfun.com/tutorials/esp32-s2-thing-plus-hookup-guide)