2.7 KiB
Supported Targets | ESP32 | ESP32-C2 | ESP32-C3 | ESP32-C6 | ESP32-H2 | 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 dinamicaly set the duty and frequency, you can use the following functions:
To set the frequency to 2.5 kHZ i.e:
ledc_set_freq(LEDC_MODE, LEDC_TIMER, 2500);
Now the duty to 100% i.e:
ledc_set_duty(LEDC_MODE, LEDC_CHANNEL, 8191);
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) - 1 = 8191
where 0 is 0% and 8191 is 100%.
Build and Flash
Build the project and flash it to the board, then run monitor tool to view serial output:
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 theLEDC_DUTY_RES
to a lower resolution and change the range of the duty.
- If you get the following error log
-
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.
- Hardware connection is not correct: run
For any technical queries, please open an issue on GitHub. We will get back to you soon.