| Supported Targets | ESP32 | ESP32-C3 | ESP32-C6 | ESP32-S2 | ESP32-S3 |
| ----------------- | ----- | -------- | -------- | -------- | -------- |

# Sigma Delta Modulation DAC Example

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

This example uses the sigma-delta driver to generate modulated output on a GPIO. If you filter the output signal with an active or passive filter, you can get a 1 KHz sine wave.

## How to use example

### Hardware Required

* A development board with any supported Espressif SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
* A USB cable for Power supply and programming
* An active or passive filter. Connect them as below:

```
┌──────────────────────────────┐
│             ESP              │     ┌───────────────────┐
│                              │     │ Active or Passive │    Sine Wave
│ EXAMPLE_SIGMA_DELTA_GPIO_NUM ├────►│      Filter       ├──────────────
└──────────────────────────────┘     └───────────────────┘
```

### Configure the project

The main configurations can be update by the macro that defined at the top of the [example source file](main/sdm_dac_example_main.c), including the output gpio, timer callback interval and the sine wave frequency and amplitude.

### Build and Flash

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

Run `idf.py -p PORT flash monitor` to build, flash and monitor the project.

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

See the [Getting Started Guide](https://docs.espressif.com/projects/esp-idf/en/latest/get-started/index.html) for full steps to configure and use ESP-IDF to build projects.

## Example Output

Once the upload is complete and the board is reset, the program should start running. This is reported on the monitor as below:

```
...
I (299) main_task: Calling app_main()
I (309) gpio: GPIO[0]| InputEn: 0| OutputEn: 1| OpenDrain: 0| Pullup: 1| Pulldown: 0| Intr:0
I (309) sdm_dac: Sigma-delta output is attached to GPIO 0
I (319) sdm_dac: Timer allocated with resolution 10000000 Hz
I (329) sdm_dac: Timer callback registered, interval 10 us
I (329) sdm_dac: Timer enabled
I (339) sdm_dac: Output start
```

After the output stated, you can monitor the sine wave after the filter by an oscilloscope.

![output_wave](output_wave.jpeg)

## Troubleshooting

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