ESP32 ADC calibration - nliaudat/esp32_8ch_motor_shield GitHub Wiki
Some ESP have very bad factory ADC calibration (eFuse Vref value burn on to the chip)
Look at https://github.com/e-tinkers/esp32-adc-calibrate to fix
Some ESP have very bad factory ADC calibration (eFuse Vref value burn on to the chip)
Look at https://github.com/e-tinkers/esp32-adc-calibrate to fix