Questions about 'Post Temperature Data and Read from Channel' example | ESP8266 Wi-Fi Module | Forum

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Questions about 'Post Temperature Data and Read from Channel' example
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July 2, 2018
7:40 am
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panoss
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June 24, 2018
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I 've built the example project 'Post Temperature Data and Read from Channel' .
In this example we have the output of a voltage divider.
It ranges from 0 to 3.3Volts and this voltage is read by the ADC of the ESP8266.

Thermistor_resistor_divider_ESP8266.pngImage Enlarger

But I read that the ESP8266 can 'read' from 0 to 1Volt.

So this project should not work correctly. But it works fine! (let me remind you that I 've built it and tested it).
So, how can this be explained?

July 3, 2018
4:32 pm
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cstapels
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That is a good catch, thanks. I think the 3.3 V is mostly dropped across the thermistor, and the voltages measured are close to 1 V anyway. Perhaps the ADC reading is still proportional to voltage for values outside the suggested range. I will try the experiment again with a 2k or 5k resistor in series. If you still have yours set up, can you try it with a lower resistor so we can compare?

July 12, 2018
10:29 am
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cstapels
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I used a NODEMCU, which has a built in voltage divider, to make the range 3.3 V.
https://github.com/nodemcu/nodemcu-devkit/blob/master/Documents/NODEMCU_DEVKIT_SCH.png

Ill add a note to the example. Thanks again!

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