87 lines
4.0 KiB
ReStructuredText
87 lines
4.0 KiB
ReStructuredText
Sigma-Delta Output
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==================
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This integration uses `sigma-delta modulation <https://en.wikipedia.org/wiki/Delta-sigma_modulation>`__
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to output a floating-point value on a binary output. Unlike with :doc:`/components/output/slow_pwm`,
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it is possible to update the output value with each update cycle, not just at the end of a longer period.
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.. figure:: images/sigma-delta-example.png
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:align: center
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:width: 65.0%
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Comparison between a *Slow PWM* with a period of 100s and a *sigma-delta output* with an update interval of 1s
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For example, if you choose to toggle the output at most once every 1 second and decide on a
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PWM period of 10 seconds, for reasonably frequent updates, with :doc:`/components/output/slow_pwm`
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there are only 10 possible levels, and for higher precision a longer update interval is needed,
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restricting the update rate.
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A *sigma-delta* output is updated during each cycle, thus a higher precision can be achieved, without
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being constrained by a calculation timeframe (=period).
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So instead of having to define a ``period`` where the width of the pulse determines the output level, here you
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choose an ``update_interval`` which acts like a clock signal from where the pulse density determines the output level.
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This component can be used as a drop-in replacement for :doc:`/components/output/slow_pwm` by changing the ``platform`` to
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``sigma_delta_output`` and changing ``period`` to ``update_interval`` (you usually want to set the *sigma-delta*'s
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``update_interval`` as a fraction of *Slow PWM*'s ``period`` for similar results)
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.. code-block:: yaml
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# Example configuration entry
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output:
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- platform: sigma_delta_output
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update_interval: 10s
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id: sd_heater_output
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# Output to a pin
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pin: 15
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# Use the same output, but through automations
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turn_on_action:
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then:
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- output.turn_on: heater_relay
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turn_off_action:
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then:
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- output.turn_off: heater_relay
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- platform: gpio
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pin: 15
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id: heater_relay
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Configuration variables:
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- **update_interval** (**Required**, :ref:`Time <config-time>`): The cycle interval at which the output is recalculated.
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- **pin** (*Optional*, :ref:`Pin Schema <config-pin_schema>`): The pin to pulse.
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- **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.
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- **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.
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- **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.
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- All options from :ref:`Output <config-output>`.
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.. note::
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- If ``pin`` is defined, the GPIO pin state is writen before any action is executed.
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- ``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.
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.. note::
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If the output must not be active for more than some fixed time before it has
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to be off for a while to e.g. cool down, :doc:`/components/output/slow_pwm`
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should be used with a ``max_power`` setting to better control the duty
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cycle.
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See Also
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--------
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- :doc:`/components/output/index`
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- :doc:`/components/output/esp8266_pwm`
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- :doc:`/components/output/ledc`
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- :doc:`/components/output/slow_pwm`
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- :doc:`/components/light/monochromatic`
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- :doc:`/components/fan/speed`
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- :doc:`/components/power_supply`
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- `Sigma-Delta <https://en.wikipedia.org/wiki/Delta-sigma_modulation>`__
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- :apiref:`sigma_delta_output/sigma_delta_output.h`
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- :ghedit:`Edit`
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