The second version of the Air Quality Monitor

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    Some time ago, I described a device for monitoring indoor air quality, which can be done independently from parts ordered at a well-known Chinese online store.

    And then a new version of the device appeared.

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    The improvements in the new version are small, mainly related to firmware. But the addition of a new BME280 sensor significantly expanded the functionality of the device.

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    Now information is available on temperature, humidity, and atmospheric pressure.
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    For those who assembled the device of the first version, its revision and improvement will be the simplest task. Just add a new sensor and re-flash the controller.

    The new sensor is connected via the I2C interface directly to the already installed clock.
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    If there is a BME280 sensor, the device will switch the panel every 15 seconds showing the dust measurement parameters to the mode of demonstrating temperature, humidity, atmospheric pressure, and after 15 seconds back to the mode of demonstrating dust.

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    The BMP280 sensor is removed from the housing so that it would not be affected by heating of the other components of the device. In the picture, this is a small radiator in the upper left corner.
    For the operation of the remaining sensors, a fan is used, which slowly blows the case.

    Even in this version, it became possible to use the device without a formaldehyde sensor. In the old firmware, without this sensor, the dust sensor did not work.

    Here  you can take a new firmware
    Here  Archive with script files
    Here is an instruction on how to assemble a similar device yourself

    Instructions on how to flash the controller can be found here .



    Electric circuit:


    Scheme


    Circuit board: 



    Additional information can be found on my website.

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