esphome-docs/components/output/ledc.rst
declanshanaghy af01734499
Adding example of how to use a buzzer (#570)
* Adding example of how to use a buzzer

* Making sub-sections
2020-05-10 16:29:49 -03:00

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ESP32 LEDC Output
=================
.. seo::
:description: Instructions for setting up LEDC hardware PWM outputs on the ESP32.
:image: pwm.png
The LEDC output component exposes a `LEDC PWM
channel <https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/ledc.html>`__
of the ESP32 as an output component.
The frequency range of LEDC is from 10Hz to 40MHz - however, higher frequencies require a smaller
bit depth which means the output is not that accurate for frequencies above ~300kHz.
Example Usage For a Light
*************************
.. code-block:: yaml
# Example configuration entry
output:
- platform: ledc
pin: GPIO19
id: gpio_19
# Example usage in a light
light:
- platform: monochromatic
output: gpio_19
name: "Kitchen Light"
Example Usage For a Piezo Buzzer
********************************
.. code-block:: yaml
# Configure the output
output:
- platform: ledc
######################################################
# One buzzer leg connected to GPIO12, the other to GND
######################################################
pin: GPIO12
id: buzzer
# Example usage in an automation
on_press:
then:
######################################################
# Must be turned on before setting frequency & level
######################################################
- output.turn_on: buzzer
######################################################
# Frequency sets the wave size
######################################################
- output.ledc.set_frequency:
id: buzzer
frequency: "1000Hz"
######################################################
# level sets the %age time the PWM is on
######################################################
- output.set_level:
id: buzzer
level: "50%"
Configuration variables:
------------------------
- **pin** (**Required**, :ref:`config-pin`): The pin to use LEDC on. Can only be GPIO0-GPIO33.
- **id** (**Required**, :ref:`config-id`): The id to use for this output component.
- **frequency** (*Optional*, float): At which frequency to run the LEDC
channels timer. Defaults to 1000Hz.
- All other options from :ref:`Output <config-output>`.
Advanced options:
- **channel** (*Optional*, int): Manually set the `LEDC
channel <https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/ledc.html#configure-channel>`__
to use. Two adjacent channels share the same timer. Defaults to an automatic selection.
Recommended frequencies
-----------------------
To get the highest available frequency while still getting the same bit depth it is
recommended to pick one of the following frequencies.
Higher bit depth means that the light has more steps available to change from one
value to another. This is especially noticeable when the light is below 10% and takes
a long transition, e.g. turning slowly off.
================================== =================================== ===================================
**Frequency** **Bit depth** **Available steps for transitions**
---------------------------------- ----------------------------------- -----------------------------------
1220Hz 16 65536
---------------------------------- ----------------------------------- -----------------------------------
2441Hz 15 32768
---------------------------------- ----------------------------------- -----------------------------------
4882Hz 14 16384
---------------------------------- ----------------------------------- -----------------------------------
9765Hz 13 8192
---------------------------------- ----------------------------------- -----------------------------------
19531Hz 12 4096
================================== =================================== ===================================
The ESP8266 for instance has *usually* a frequency of 1000Hz with a resolution of 10 bits.
This means that there are only 4 steps between each value.
.. _output-ledc-set_frequency_action:
``output.ledc.set_frequency`` Action
------------------------------------
This :ref:`Action <config-action>` allows you to manually change the frequency of an LEDC
channel at runtime. Use cases include controlling a passive buzzer (for pitch control).
.. code-block:: yaml
on_...:
- output.ledc.set_frequency:
id: ledc_output
frequency: 100Hz
Configuration variables:
- **id** (**Required**, :ref:`config-id`): The ID of the LEDC output to change.
- **frequency** (**Required**, :ref:`templatable <config-templatable>`, float): The frequency
to set in hertz.
See Also
--------
- :doc:`/components/output/index`
- :doc:`/components/output/esp8266_pwm`
- :doc:`/components/light/monochromatic`
- :doc:`/components/fan/speed`
- :doc:`/components/power_supply`
- :apiref:`ledc/ledc_output.h`
- `esp-idf LEDC API docs <https://docs.espressif.com/projects/esp-idf/en/latest/api-reference/peripherals/ledc.html>`__
- :ghedit:`Edit`