Building a WiFi weatherstation

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michelm
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Joined: 04 Jan 2018, 21:53

Building a WiFi weatherstation

#1 Post by michelm » 04 Jan 2018, 22:13

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
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Posts: 307
Joined: 06 Nov 2016, 13:45

Re: Building a WiFi weatherstation

#2 Post by Domosapiens » 05 Jan 2018, 00:14

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
30+ ESP units for production and test. Ranging from control of heating equipment, flow sensing, floor temp sensing, energy calculation, floor thermostat, water usage, to an interactive "fun box" for my grandson. Mainly Wemos D1.

Ton_vN
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Joined: 21 Oct 2016, 15:20
Location: Hengelo (Ov)/ NL
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Re: Building a WiFi weatherstation

#3 Post by Ton_vN » 23 Jan 2018, 22:19

Which mark & model of UV-device?

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