Sigma-Delta Output
==================

This integration uses `sigma-delta modulation <https://en.wikipedia.org/wiki/Delta-sigma_modulation>`__
to output a floating-point value on a binary output. Unlike with :doc:`/components/output/slow_pwm`,
it is possible to update the output value with each update cycle, not just at the end of a longer period.

.. figure:: images/sigma-delta-example.png
    :align: center
    :width: 65.0%

    Comparison between a *Slow PWM* with a period of 100s and a *sigma-delta output* with an update interval of 1s

For example, if you choose to toggle the output at most once every 1 second and decide on a
PWM period of 10 seconds, for reasonably frequent updates, with :doc:`/components/output/slow_pwm`
there are only 10 possible levels, and for higher precision a longer update interval is needed,
restricting the update rate. 

A *sigma-delta* output is updated during each cycle, thus a higher precision can be achieved, without
being constrained by a calculation timeframe (=period).

So instead of having to define a ``period`` where the width of the pulse determines the output level, here you
choose an ``update_interval`` which acts like a clock signal from where the pulse density determines the output level. 

This component can be used as a drop-in replacement for :doc:`/components/output/slow_pwm` by changing the ``platform`` to
``sigma_delta_output`` and changing ``period`` to ``update_interval`` (you usually want to set the *sigma-delta*'s
``update_interval`` as a fraction of *Slow PWM*'s ``period`` for similar results)

.. code-block:: yaml

    # Example configuration entry
    output:
      - platform: sigma_delta_output
        update_interval: 10s
        id: sd_heater_output

        # Output to a pin
        pin: 15

        # Use the same output, but through automations
        turn_on_action:
          then:
            - output.turn_on: heater_relay
        turn_off_action:
          then:
            - output.turn_off: heater_relay
    
      - platform: gpio
        pin: 15
        id: heater_relay

Configuration variables:

- **update_interval** (**Required**, :ref:`Time <config-time>`): The cycle interval at which the output is recalculated.
- **pin** (*Optional*, :ref:`Pin Schema <config-pin_schema>`): The pin to pulse.
- **state_change_action** (*Optional*, :ref:`Automation <automation>`): An automation to perform when the load is switched. If a lambda is used the boolean ``state`` parameter holds the new status.
- **turn_on_action** (*Optional*, :ref:`Automation <automation>`): An automation to perform when the load is turned on. Can be used to control for example a switch or output component.
- **turn_off_action** (*Optional*, :ref:`Automation <automation>`): An automation to perform when the load is turned off. ``turn_on_action`` and ``turn_off_action`` must be configured together.
- All options from :ref:`Output <config-output>`.

.. note::

    - If ``pin`` is defined, the GPIO pin state is writen before any action is executed.
    - ``state_change_action`` and ``turn_on_action``/``turn_off_action`` can be used togther. ``state_change_action`` is called before ``turn_on_action``/``turn_off_action``. It's recommended to use either ``state_change_action`` or ``turn_on_action``/``turn_off_action`` to change the state of an output. Using both automations together is only recommended for monitoring.


.. note::

    If the output must not be active for more than some fixed time before it has
    to be off for a while to e.g. cool down, :doc:`/components/output/slow_pwm`
    should be used with a ``max_power`` setting to better control the duty
    cycle.

See Also
--------

- :doc:`/components/output/index`
- :doc:`/components/output/esp8266_pwm`
- :doc:`/components/output/ledc`
- :doc:`/components/output/slow_pwm`
- :doc:`/components/light/monochromatic`
- :doc:`/components/fan/speed`
- :doc:`/components/power_supply`
- `Sigma-Delta <https://en.wikipedia.org/wiki/Delta-sigma_modulation>`__
- :apiref:`sigma_delta_output/sigma_delta_output.h`
- :ghedit:`Edit`