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EC Meter issue with ESP and or ADS1115

PostPosted: Mon Jul 23, 2018 5:06 am
by cybergogo
Hi everybody.

I've been successfully reading EC with this code and my arduino UNO & Mega:
https://hackaday.io/project/7008-fly-wa ... ssion-list

But the thing is, when i try with my ESP32 on an ADC port, i get incoherent voltages. Same thing with an arduino + ADS1115.

For example :

Arduino+EC sensor+ 1.55mS calibration solution : Value read : 403 (so 1.96v)

Arduino+EC sensor+ 2.8mS calibration solution : Value read : 277 (so 1.35v)

Arduino without sensor plugged : Value read : 1023 (so 5v)

Arduino+ADS1115@15bits+EC sensor+ 1.55mS calibration solution : Value read : 24560 (so 4.6v)

Arduino+ADS1115@15bits+EC sensor+ 2.8mS calibration solution : Value read : 25520 (so 4.79v)

Arduino+ADS1115@15bits without sensor plugged : Value read : 27000 (so 5v under 15bits)

I'm always using a 1kohms resistor for those tests (between +5v and analog signal).

I don't have the numbers now for the ESP32+sensor@3.3v but it's the same than with the ADS (voltages read higher than on arduino).

Do someone have an idea about what is happening here?

I'm reaching the limit of my basic knowledge here :-(