mirror of
https://github.com/espressif/esp-idf.git
synced 2024-10-05 20:47:46 -04:00
c0a1d27858
Update ledc duty cycle value range in doxygen. Fix duty configuration error at 100% duty cycle for ESP32. Improve LEDC API doxygen. Closes https://github.com/espressif/esp-idf/pull/11516 Closes https://github.com/espressif/esp-idf/issues/12593 Closes https://github.com/espressif/esp-idf/issues/12083
83 lines
2.7 KiB
Markdown
83 lines
2.7 KiB
Markdown
| Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-S2 | ESP32-S3 |
|
|
| ----------------- | ----- | -------- | -------- | -------- | -------- |
|
|
|
|
# _LEDC Basic Example_
|
|
|
|
(See the README.md file in the upper level 'examples' directory for more information about examples.)
|
|
|
|
This example shows how to use the LEDC to generate a PWM signal using the `LOW SPEED` mode.
|
|
To use `HIGH SPEED` mode check if the selected SoC supports this mode.
|
|
|
|
## How to use example
|
|
|
|
### Hardware Required
|
|
|
|
* A development board with any Espressif SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
|
|
* A USB cable for power supply and programming
|
|
|
|
Connect the GPIO to an oscilloscope to see the generated signal:
|
|
|
|
|ledc channel| GPIO |
|
|
|:----------:|:-----:|
|
|
| Channel 0 | GPIO5 |
|
|
|
|
### Configure the project
|
|
|
|
The example uses fixed PWM frequency of 5 kHz, duty cycle in 50%, and output GPIO pin. To change them, adjust `LEDC_FREQUENCY`, `LEDC_DUTY`, `LEDC_OUTPUT_IO` macros at the top of ledc_basic_example_main.c.
|
|
|
|
Depending on the selected `LEDC_FREQUENCY`, you will need to change the `LEDC_DUTY_RES`.
|
|
|
|
To dynamically set the duty and frequency, you can use the following functions:
|
|
|
|
To set the frequency to 2.5 kHZ i.e:
|
|
|
|
```c
|
|
ledc_set_freq(LEDC_MODE, LEDC_TIMER, 2500);
|
|
```
|
|
|
|
Now set the duty to 100% i.e:
|
|
|
|
```c
|
|
ledc_set_duty(LEDC_MODE, LEDC_CHANNEL, 8192);
|
|
ledc_update_duty(LEDC_MODE, LEDC_CHANNEL);
|
|
```
|
|
|
|
To change the duty cycle you need to calculate the duty range according to the duty resolution.
|
|
|
|
If duty resolution is 13 bits:
|
|
|
|
Duty range: `0 to (2 ** 13) = 8192` where 0 is 0% and 8192 is 100%.
|
|
|
|
### Build and Flash
|
|
|
|
* [ESP-IDF Getting Started Guide](https://idf.espressif.com/)
|
|
|
|
Build the project and flash it to the board, then run monitor tool to view serial output:
|
|
|
|
```bash
|
|
idf.py -p PORT 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 PWM signal with a duty cycle of 50%.
|
|
|
|
|
|
|
|
## Troubleshooting
|
|
|
|
* Duty Resolution
|
|
|
|
* If you get the following error log `ledc: requested frequency and duty resolution can not be achieved, try reducing freq_hz or duty_resolution.` you need to change the `LEDC_DUTY_RES` to a lower resolution and change the range of the duty.
|
|
|
|
* Programming fail
|
|
|
|
* Hardware connection is not correct: run `idf.py -p PORT 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.
|