ADC2 channel 0 is GPIO4 (ESP32), GPIO11 (ESP32-S2).
ADC2 channel 1 is GPIO0 (ESP32), GPIO12 (ESP32-S2).
ADC2 channel 2 is GPIO2 (ESP32), GPIO13 (ESP32-S2).
ADC2 channel 3 is GPIO15 (ESP32), GPIO14 (ESP32-S2).
ADC2 channel 4 is GPIO13 (ESP32), GPIO15 (ESP32-S2).
ADC2 channel 5 is GPIO12 (ESP32), GPIO16 (ESP32-S2).
ADC2 channel 6 is GPIO14 (ESP32), GPIO17 (ESP32-S2).
ADC2 channel 7 is GPIO27 (ESP32), GPIO18 (ESP32-S2).
ADC2 channel 8 is GPIO25 (ESP32), GPIO19 (ESP32-S2).
ADC2 channel 9 is GPIO26 (ESP32), GPIO20 (ESP32-S2).