ML8511, why not always use EN pin?

Other Hardware Sensors
1

Hello
i have a wemos d1 and want to use the ML8511.

I found some tutorials. It's a little bit strange.... sometimes the wiring connect EN to 3.3v and in other tutorilas the leave it blank

here are two different tutorials

What does the EN pin do?

thank you a lot
https://learn.sparkfun.com/tutorials/ml8511-uv-sensor-hookup-guide/all

2

I'm not sure, but I believe that if you leave EN unconnected it is the same as setting it to HIGH, but I recommend connecting to 3.3V.

The datasheet say " EN I Active high enable pin. (High: Active mode, Low: Standby mode)

and

TIMING CHART
Supply voltage and EN signal state should take one of the following procedures:

  1. EN should be HIGH or LOW at the same time when VDD is applied.
  2. EN should be HIGH or LOW while VDD is applied.

" https://cdn.sparkfun.com/datasheets/Sensors/LightImaging/ML8511_3-8-13.pdf?_gl=1*ke92jp*_ga*MjE4OTcxODYwLjE3MDA0MzQzMjM.*_ga_T369JS7J9N*MTcwMDQzNDMyMi4xLjEuMTcwMDQzNDM1OS4yMy4wLjA.

3

okay. thank you
the sensor show me values in mw/cm²
do you know if i can calculate it to the UV-Index???
i found a duv-factor 1.61 but i don't know if ít is correct.

4

UV Sensor Application Note: UV Index Measurement.

How do you convert irradiance to UV Index?

This gives us an Erythema corrected irradiance figure of 0.0916 W/m2. The UV Index itself is an irradiance scale calculated by multiplying the Erythema corrected irradiance in watts per m2 by 40. This gives us a UV index figure for the sample of 0.0916 x 40 = 3.66.

5

thank you for the doument

i found the factor 40 too. but that's confuse.
For example:

my ML8511 shows me the value: 0.80mw/cm²

this should be 8 w/m².

When i multiplicate it, i will get 320. the uv-index is from 1-15.

???

7

at this moment i get a outputVoltage from the A0 oin about 1.09, but it's night. Fully dark outside...

but i knwo, that the wemos d1 has a constant A0 reading volt, without any sensors too.
on a other wemos i have always around ~2.25mV. So maybe this is the reason, for the postivie value although it is dark

8

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