Calibration of analog sensor

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Dennis Roschke
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Joined: 21 May 2018, 22:37

Calibration of analog sensor

#1 Post by Dennis Roschke » 21 May 2018, 23:16

Hello to everyone,
I am very confused right now. I´m trying to connect several ADC sensors to my ESP chip for days now.

My project:
I am using a raspberry pi 3b with IO broker and mqtt. I want to transfer the ADC values to IO broker.
The moisture sensors are connectred to a ESP 32 - the plan is to monitor the water level of a few plants. If the soil gets too dry, a water pump starts to water it again.

Everything is fine until it comes to the point of calibration. I want the sensors to start at 0, but I simply dont get it.
At this moment there are two different sensors that are planned to have the same task (If they are completely dry they show a value of around 16126 and 39). If it is completely dry i want to calibrate the sensor to display 0. If it is completely wet it should display any value that is high enough. It also could the other way round (eg. completely dry: 1000, completely wet: 0).
I dont know if the settings are correct.
Gain - 2/3x gain (FS=6.144V)
Input Multiplexer - AIN0-GND (single ended)
No ,,two point calibration"

Well I hope there is someone who is knowing well about this concept to help me.
(If there are any mistakes in this text, please excuse. English is not my mothertongue.)
If there should be anything unclear or if you have questions, please let me know, so I´ll try to explain it again.

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Joined: 11 May 2017, 01:19

Re: Calibration of analog sensor

#2 Post by danmero » 22 May 2018, 13:10

Min and Max are relative especially for analog, try values in between, like less that %5 equal %0 and greater that %95 equal %100
What is your max Vc max?


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