esp-idf/examples/peripherals/adc/README.md

# ADC1 Example

(See the README.md file in the upper level 'examples' directory for more information about examples.)

This example shows how to configure ADC1 and read the voltage connected to GPIO pin.

## How to use example

### Hardware Required

* A development board with ESP32 SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
* A USB cable for power supply and programming

In this example, we use `ADC_UNIT_1` by default, we need to connect a voltage source (0 ~ 3.3v) to GPIO34. If another ADC unit is selected in your application, you need to change the GPIO pin (please refer to Chapter 4.11 of the `ESP32 Technical Reference Manual`).

### Configure the project

```
make menuconfig
```

* Set serial port under Serial Flasher Options.

### Build and Flash

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

```
make -j4 flash monitor
```

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

See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.

## Example Output

Running this example, you will see the following log output on the serial monitor:

```
Raw: 486	Voltage: 189mV
Raw: 435	Voltage: 177mV
Raw: 225	Voltage: 128mV
Raw: 18	    Voltage: 79mV
```

## Troubleshooting

* program upload failure

    * Hardware connection is not correct: run `make monitor`, and reboot your board to see if there are any output logs.
    * The baud rate for downloading is too high: lower your baud rate in the `menuconfig` menu, and try again.

For any technical queries, please open an [issue](https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you soon.