VEML 6075 UV negative values

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kevinjwalters
 
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VEML 6075 UV negative values

Post by kevinjwalters »

I've had a VEML 6075 for a while now. I was sad to see that it's discontiued but I finally soldered the header on at the weekend. Monday obliged with some sunshine. It was fine until I allowed direct (winter) sunlight onto the sensor and then the values went very negative. It's fine as long as it doesn't get a direct blast. Is the sensor designed for direct exposure?

I'm using the CircuitPython library. Similar report of testing under the sun in UV Sensor Veml 6075 bad reading although only the UVB has gone negative there.

I see the library's got a compensation equation in it based on the application note. I thought it might only be intended for use behind an attenuating filter/cover but that note describes a comparison with 100ms integration time with Davis 6490 UVI sensor with some uncovered sensors.

I was running it on 100ms integration time. There appears to be a slightly mysterious HD bit that sets "0 = normal dynamic setting, 1 = high dynamic setting". I'll have a look at the raw values and maybe play with that HD thing.

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kevinjwalters
 
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Re: VEML 6075 UV negative values

Post by kevinjwalters »

I looked at the raw (16 bit) values and those behave themselves. In low/morning winter sun at 50ms integration time I got about (3400,4200) and in mysterious HD mode (1800, 2200).

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