ADC Options for WiFi Kit 32


I am attempting to use a WiFi Kit 32 as a remote battery monitor, which reports to me by WiFi when the battery gets low. I have that circuit working, but when I tried to use analogReference, the compiler advises me that that instruction is "not declared within this scope". So apparently this chip requires some other reference, or only has a default built in? I really can't find any clarification of this online. Any help would be greatly appreciated.

Thanks in advance for any thoughts.


Which microcontroller does this WiFi Kit 32 use?

The Wifi Kit 32 uses an ESP32.