Building a WiFi weatherstation
Posted: 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?
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?