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a6798eac98
Changes on the ledc_init function Review on the README, docs and example functions Added how to set freq and duty on README Fix on the ledc.rst docs in the App Example Added new example reference in the Chinese docs
80 lines
2.6 KiB
Markdown
80 lines
2.6 KiB
Markdown
# _LEDC Basic Example_
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(See the README.md file in the upper level 'examples' directory for more information about examples.)
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This example shows how to use the LEDC to generate a PWM signal using the `LOW SPEED` mode.
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To use `HIGH SPEED` mode check if the selected SoC supports this mode.
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## How to use example
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### Hardware Required
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* A development board with ESP32, ESP32-S2, ESP32-C3 or ESP32-S3 SoC (e.g., ESP32-DevKitC, ESP-WROVER-KIT, etc.)
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* A USB cable for power supply and programming
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Connect the GPIO to an oscilloscope to see the generated signal:
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|ledc channel| GPIO |
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|:----------:|:-----:|
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| Channel 0 | GPIO5 |
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### Configure the project
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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.
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Depending on the selected `LEDC_FREQUENCY`, you will need to change the `LEDC_DUTY_RES`.
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To dinamicaly set the duty and frequency, you can use the following functions:
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To set the frequency to 2.5 kHZ i.e:
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```c
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ledc_set_freq(LEDC_MODE, LEDC_TIMER, 2500);
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```
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Now the duty to 100% i.e:
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```c
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ledc_set_duty(LEDC_MODE, LEDC_CHANNEL, 8191);
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ledc_update_duty(LEDC_MODE, LEDC_CHANNEL);
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```
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To change the duty cycle you need to calculate the duty range according to the duty resolution.
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If duty resolution is 13 bits:
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Duty range: `0 to (2 ** 13) - 1 = 8191` where 0 is 0% and 8191 is 100%.
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### Build and Flash
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* [ESP-IDF Getting Started Guide](https://idf.espressif.com/)
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Build the project and flash it to the board, then run monitor tool to view serial output:
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```bash
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idf.py -p PORT flash monitor
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```
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(To exit the serial monitor, type ``Ctrl-]``.)
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See the Getting Started Guide for full steps to configure and use ESP-IDF to build projects.
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## Example Output
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Running this example, you will see the PWM signal with a duty cycle of 50%.
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## Troubleshooting
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* Duty Resolution
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* 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.
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* Programming fail
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* Hardware connection is not correct: run `idf.py -p PORT monitor`, and reboot your board to see if there are any output logs.
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* The baud rate for downloading is too high: lower your baud rate in the `menuconfig` menu, and try again.
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For any technical queries, please open an [issue](https://github.com/espressif/esp-idf/issues) on GitHub. We will get back to you soon.
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