kopia lustrzana https://github.com/espressif/esp-idf
80 wiersze
2.5 KiB
Markdown
80 wiersze
2.5 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 any Espressif 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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