Espressif ESP32 Technical Reference Manual page 640

29 On-Chip Sensors and Analog Signal Processing
29.3 SAR ADC
29.3.1 Introduction
ESP32 integrates two 12-bit SAR ADCs. They are managed by five SAR ADC controllers, and are able to measure
signals from one to 18 analog pads.
The SAR ADC controllers have specialized uses. Two of them support high-performance multiple-channel scan-
ning. Another two are used for low-power operation during Deep-sleep, and the last one is dedicated to PWDET
/ PKDET (power and peak detection). A diagram of the SAR ADCs is shown in Figure 29-5.
Note:
PWDET/PKDET controller is for Wi-Fi internal use only. If Wi-Fi module is using the SAR ADC2, users can not measure
the analog signal from the pins using SAR ADC2. After SAR ADC2 is released by Wi-Fi, users can use SAR ADC2 normally.
Espressif Systems
Figure 29-4. Touch FSM Structure
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