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Analog-to-Digital Converter (ADC)

Overview

This sample demonstrates how to use the ADC driver API.

Depending on the target board, it reads ADC samples from one or more channels and prints the readings on the console. If voltage of the used reference can be obtained, the raw readings are converted to millivolts.

The pins of the ADC channels are board-specific. Please refer to the board or MCU datasheet for further details.

Building and Running

The ADC peripheral and pinmux is configured in the board’s .dts file. Make sure that the ADC is enabled (status = "okay";).

In addition to that, this sample requires an ADC channel specified in the io-channels property of the zephyr,user node. This is usually done with a devicetree overlay. The example overlay in the boards subdirectory for the nucleo_l073rz board can be easily adjusted for other boards.

Configuration of channels (settings like gain, reference, or acquisition time) can be specified in devicetree, in ADC controller child nodes. Also the ADC resolution and oversampling setting to be used for particular channels can be specified there. See boards/nrf52840dk_nrf52840.overlay for an example of such setup. If these parameters are not specified in devicetree, default values, supposed to be supported by most ADCs, are used instead.

Building and Running for ST Nucleo L073RZ

The sample can be built and executed for the ST Nucleo L073RZ as follows:

west build -b nucleo_l073rz samples/drivers/adc
west flash

To build for another board, change “nucleo_l073rz” above to that board’s name and provide a corresponding devicetree overlay.

Sample output

You should get a similar output as below, repeated every second:

ADC reading(s): 42 (raw)

Note

If the ADC is not supported, the output will be an error message.