ADS1015 The ADS1015 is a 12 bit ADC which is connected via I2C. Pins: ADS1015 ESP32 VDD 3.3 GND GND SCL SCL GPIO22 SDA SDA GPIO21 ADDR GND ALRT - A0 Analog Source (e.g. Electic Guitar) Conclusion The sampling rate is too low to be usefull.