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57 lines
2.4 KiB
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57 lines
2.4 KiB
ReStructuredText
TEMT6000
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========
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The TEMT6000 is a simple and cheap ambient light sensor. The sensor itself
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changes its resistance based on how much light hits the sensor. In order
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for us to read this resistance the breakout boards you can buy these chips on
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often have a small constant value resistor and three pins: ``GND``, ``VCC`` and
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``SIG``. Connect ``VCC`` to ``3.3V``, ``GND`` to ``GND`` and ``SIG`` to any
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available :doc:`analog pin </esphomeyaml/components/sensor/adc>`.
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To get the brightness the sensor measures, we then simply have to measure the voltage
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on the ``SIG`` pin using the :doc:`/esphomeyaml/components/sensor/adc` and convert those
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voltage measurements to illuminance values in lux using a forumla:
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.. code:: yaml
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- platform: adc
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pin: A0
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name: "TEMT6000 Illuminance"
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unit_of_measurement: lux
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filters:
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- lambda: >-
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return (x / 10000.0) * 2000000.0;
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Formula Explanation:
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^^^^^^^^^^^^^^^^^^^^
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To get the illuminance in lux, we first need to convert the measured voltage to the
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current flowing across the TEMT6000 sensor. This current is also equal to the current
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flowing across the 10kΩ resistor in the voltage divider circuit, which is
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``I = adc_value/10000kΩ``.
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The `datasheet for the TEMT6000 <https://www.sparkfun.com/datasheets/Sensors/Imaging/TEMT6000.pdf>`__
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specifies a proportional correlation between current and illuminance: Every 2 µA of current
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correlates to 1 lx in the illuminance.
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.. note::
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The default voltage range of the ADC for the ESP8266 and ESP32 are from 0 to 1.0V.
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So you won't be able to measure any value above 200 lx using the default setup.
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For the ESP32, you have the option of setting a :ref:`Voltage Attenuation <adc-esp32_attenuation>`
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(note that the formula doesn't need to be adjusted if you set an attenuation, as the value ``x``
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is automatically converted to volts).
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For the ESP8266, you unfortunately need to tinker with the hardware a bit to decrease
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the voltage a bit. So one option would be to create another voltage divider on the ``SIG`` pin
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to divide the analog voltage by a constant value.
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See Also
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^^^^^^^^
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- :doc:`/esphomeyaml/components/sensor/adc`
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- `TEMT6000 datasheet <https://www.sparkfun.com/datasheets/Sensors/Imaging/TEMT6000.pdf>`__
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- :doc:`bruh`
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- `Edit this page on GitHub <https://github.com/OttoWinter/esphomedocs/blob/current/esphomeyaml/cookbook/temt6000.rst>`__
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