LTR390 UV and Ambient Light Sensor ================================================== .. seo:: :description: Instructions for setting up LTR390 UV and light sensor :image: ltr390.jpg The ``ltr390`` sensor platform allows you to use your LTR390 UV and ambient light sensor (`datasheet `__, `Adafruit`_) with ESPHome. The :ref:`I²C Bus ` is required to be set up in your configuration for this sensor to work. .. figure:: images/ltr390-full.jpg :align: center :width: 80.0% .. _Adafruit: https://www.adafruit.com/product/4831 .. code-block:: yaml sensor: - platform: ltr390 uv_index: name: "UV Index" uv: name: "UV Sensor Counts" light: name: "Light" ambient_light: name: "Light Sensor Counts" Configuration variables: ------------------------ - **uv_index** (*Optional*): UV index (UVI). All options from :ref:`Sensor `. - **uv** (*Optional*): Sensor counts for the UV sensor (#). All options from :ref:`Sensor `. - **light** (*Optional*): Lux of ambient light (lx). All options from :ref:`Sensor `. - **ambient_light** (*Optional*): Sensor counts for the Ambient light sensor (#). All options from :ref:`Sensor `. - **gain** (*Optional*, string): Adjusts the sensitivity of the sensor. A larger value means higher sensitivity. Default is ``"X18"``, see table below for options. - **resolution** (*Optional*, int): ADC resolution. Higher resolutions require longer sensor integration times. Default is ``20``, see table below for options. - **window_correction_factor** (*Optional*, float): Window correction factor. Use larger values when using under tinted windows. Default is ``1.0``, must be ``>= 1.0``. - **address** (*Optional*, int): Manually specify the I²C address of the sensor. Default is ``0x53``. - **update_interval** (*Optional*, :ref:`config-time`): The interval to check the sensor. Defaults to ``60s``. It is recommended that the update interval is at least 1 second since updates can take up to 800ms when using a high resolution value. Lux and UVI Formulas -------------------- .. math:: \text{lux} = \frac{0.6 \times \text{als}}{\text{gain} \times \frac{\text{int}}{100} } \times \text{wfac} .. math:: \text{UVI} = \frac{\text{uv}}{\text{sensitivity}} \times \text{wfac} where: - ``als`` and ``uv`` are the sensor values. - ``gain`` is the sensor gain, see the table below for details. - ``int`` is the integration time in ms and is tied to the resolution, see the table below for details. - ``sensitivity`` is the sensor's count per UVI. See note below for details. - ``wfac`` is the window correction factor. It is recommended to use the defaults of ``X18`` gain and resolution of 20 bits when UV Index sensing is required since the data sheet only provides accurate conversion formula for this combination. The UVI value is linearly scaled from this reference point when using other combinations of gain and resolution, which may be slightly inaccurate. The scaling formula is: .. math:: \text{sensitivity} = 2300 \times \frac{\text{gain}}{18} \times \frac{\text{int}}{400} where :math:`2300` is the sensor count per UVI at the default configuration. Gain ---- .. list-table:: :widths: 25 25 :header-rows: 1 * - Configuration value - gain * - X1 - 1 * - X3 - 3 * - X6 - 6 * - X9 - 9 * - X18 - 18 Resolution ---------- .. list-table:: :widths: 25 25 10 :header-rows: 1 * - Configuration value - Resolution (bits) - Integration Time (ms) * - 16 - 16 - 25 * - 17 - 17 - 50 * - 18 - 18 - 100 * - 19 - 19 - 200 * - 20 - 20 - 400 See Also -------- - :doc:`/components/sensor/bh1750` - :doc:`/components/sensor/tsl2561` - `TEMT6000 `__ - :ref:`sensor-filters` - :apiref:`ltr390/ltr390.h` - :ghedit:`Edit`