Building a WiFi weatherstation

[michelm]

Allright, before I continue you should know that I’m an espNOOB and that this is me first project.

I’m building an WiFi weatherstation using a NodeMCU Esp board (for ease of use), the great Lets Control It firmware and several sensors. Most of the sensors I’m using make use of the I2C protocol...... exept for one. An UV sensor. It uses the ADC converter on pin AO. Al is working well exept the UV sensor.

The UV sensor uses the following specs:

Input voltage: 3.3 v
Output voltages: 0.96v to 2.8v where 0.96 volt equals 0 UVI and 2.8v equals 15 UVI

Because the ADC of the ESP can only read up to 1v I have made a voltage divider. With the voltage divider in place it know outputs 0.375v to 1.05v. Close enough for me.

Next I added a new Analog Input device in the firmware. I used the new calibration section and added the following values:

0 = 0.375
15 = 1.000

I’ve measured the output voltage when there is no UV light and it outputs 0.375v. Therefore the calculated sensorvalue should give exactly 0. But instead of a 0 it gives a 0.50.

What am I missing?

[Domosapiens]

Without a screenshot, it is just an assumption,
But I assume you swapped the values.

First field is what you measure, second field is what it means.
The sign in the middle means "equals"

So your values should be:
0.375 ... 0
1.000 ... 15

Hope this helps
Domosapiens

[Ton_vN]

Which mark & model of UV-device?