ADC Example

This example shows the use of the espp::OneshotAdc and the espp::ContinuousAdc components.

It uses the following components:

• adc

• logger

• task

These adc components can be used to read analog values using the ESP’s built-in ADC hardware, supporting DMA and filtering as well.

How to use example

You can build and run this example on any esp dev board, such as the QtPy ESP32 series, the TinyPICO / TinyS3 boards, the WROVER-DevKit, and the M5Stack Tab5. Make sure to set the idf target when building the example.

Configure

Select which ADC unit / channels the example reads via the ADC Example Configuration menu:

idf.py menuconfig

The Hardware option has selections for specific boards which set the ADC unit and channels to pins that are usable (exposed) on that board:

Hardware	Unit	Channels	Pins
Adafruit QtPy ESP32 Pico	1	4, 5	GPIO32 (TX), GPIO33 (SCL)
Adafruit QtPy ESP32-S3	1	7, 8	GPIO8 (A3), GPIO9 (A2)
M5Stack Tab5 (ESP32-P4)	1	0, 1	GPIO16 / GPIO17 (expansion header)
Custom	any	any	your choice

With Custom, set the ADC unit and the two channels yourself. Note that the continuous (DMA) portion of the example requires a DMA-capable unit; on ESP32 / ESP32-C3 / ESP32-S3 that is only unit 1, and on ESP32-P4 ADC2 continuous conversions currently produce all-zero samples with esp-idf (oneshot on ADC2, e.g. the Tab5’s Grove pins GPIO53/54, works fine).

Build and Flash

Build the project and flash it to the board, then run monitor tool to view serial output:

idf.py -p PORT flash monitor

(Replace PORT with the name of the serial port to use.)

(To exit the serial monitor, type Ctrl-].)

Example Output