89 lines
3.2 KiB
ReStructuredText
89 lines
3.2 KiB
ReStructuredText
HX711 Load Cell Amplifier
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=========================
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.. seo::
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:description: Instructions for setting up HX711 load cell amplifiers with esphomelib
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:image: hx711.svg
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:keywords: HX711
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The ``hx711`` sensor platform allows you to use your HX711
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load cell amplifier
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(`datasheet <https://www.mouser.com/ds/2/813/hx711_english-1022875.pdf>`__, `Sparkfun`_) with esphomelib
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.. figure:: images/hx711-full.jpg
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:align: center
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:target: `Sparkfun`_
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:width: 60.0%
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HX711 Load Cell Amplifier. Image by `Sparkfun`_ licensed and re-distributed under `CC BY 2.0 <https://creativecommons.org/licenses/by/2.0/>`__.
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.. _Sparkfun: https://www.sparkfun.com/products/13879
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Connect ``GND`` to ``GND``, ``VCC`` to ``3.3V`` and the other three ``MISO`` (or ``SO`` for short),
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``CS`` and ``CLOCK`` (or ``SCK``) to free GPIO pins.
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.. code:: yaml
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# Example configuration entry
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sensor:
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- platform: hx711
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name: "HX711 Value"
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dout_pin: D0
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clk_pin: D1
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gain: 128
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update_interval: 15s
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Configuration variables:
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------------------------
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- **name** (**Required**, string): The name for the load cell sensor.
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- **dout_pin** (**Required**, :ref:`Pin Schema <config-pin_schema>`): The DOUT (or DAT) pin.
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- **clk_pin** (**Required**, :ref:`Pin Schema <config-pin_schema>`): The CLK pin.
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- **update_interval** (*Optional*, :ref:`config-time`): The interval to check the sensor. Defaults to ``15s``.
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See :ref:`sensor-default_filter`.
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- **id** (*Optional*, :ref:`config-id`): Manually specify the ID used for code generation.
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- All other options from :ref:`Sensor <config-sensor>` and :ref:`MQTT Component <config-mqtt-component>`.
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Converting Units
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----------------
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As the HX711 does not have any calibration data, you have to convert the measurement to units yourself.
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To calibrate the sensor:
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1. Place nothing or a known mass on the sensor, for example ``0kg``
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2. Wait for the data to arrive in the logs and write down the value. For example ``120``.
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3. Place another (different) known mass on the sensor, for example ``1kg``
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4. Again wait for the data to arrive and note the value, for example ``810``.
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Once you've done those steps, you can use the ``map`` function to map the incoming value to the calibrated one:
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.. code:: yaml
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# Example configuration entry
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sensor:
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- platform: hx711
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# ... Other HX711 options
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filters:
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- lambda: |-
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auto first_mass = 0.0; // first known mass was 0kg
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auto first_value = 120.0; // value for the first known mass was 120
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auto second_mass = 1.0; // second mass was 1kg
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auto second_value = 810.0; // second value was 810
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return map(x, first_value, second_value, first_mass, second_mass);
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unit_of_measurement: kg
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Replace the masses and values ``120.0``, ``810.0``, etc with your values.
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See Also
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--------
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- :ref:`sensor-filters`
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- :doc:`adc`
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- :doc:`API Reference </api/sensor/hx711>`
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- `HX711 Library <https://github.com/bogde/HX711>`__ by `@bogde <https://github.com/bogde>`__
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- `Edit this page on GitHub <https://github.com/OttoWinter/esphomedocs/blob/current/esphomeyaml/components/sensor/hx711.rst>`__
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.. disqus::
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