Calculate the light


Is it possible to convert the ADC values from the light sensor to some known SI unit, like lux?
I couldn’t find any curve or specifications in the datasheet?

No - the API for the internal light sensor was really designed to give a rough idea of whether it’s bright or dark out.

The value will change based on the enclosure and how much light is let in through the light pipe vs the top of the card (in the case of the imp001) and on how you tune the BlinkUp circuit (in the case of imp002 and imp003).

In my experience the reading is about 25% of full scale even in complete darkness. Do others find this?

It should be pretty near zero in full darkness (this is what I see). However, it’s much more sensitive to IR than other wavelengths. Any IR sources about?

Lux calculation is hard and generally requires a wideband sensor vs a mostly IR sensitive one like the imp has.