Analog READ - Precision?

E-M-Dev
Posts: 10
Joined: Sun Apr 02, 2017 3:57 pm

Analog READ - Precision?

Postby E-M-Dev » Wed May 31, 2017 10:02 pm

Hello,

Is there a solution for Analog READ (silicon revision 0) allready?
I'm reading 1438-1440 for 1,32V (@3.33V Supply).

No matter if floating or with pulldown, the readings are allways the same.
Basically accurate with a shift of -0.15V

Regards,
Rick

ukonline2000
Posts: 1
Joined: Mon Jun 05, 2017 12:06 pm

Re: Analog READ - Precision?

Postby ukonline2000 » Mon Jun 05, 2017 12:09 pm

yes,me too. I'm reading IO39 for 1.71V ~1.75V(The actual voltage is 1.9V). :(

E-M-Dev
Posts: 10
Joined: Sun Apr 02, 2017 3:57 pm

Re: Analog READ - Precision?

Postby E-M-Dev » Tue Jun 06, 2017 7:04 pm

Can anybody from espressif please make a statement on this problem?

Basically I don't need to measure Voltages lower than 0.15v
but I would like to be sure about what is going on there.

@ukonline2000 Currently I correct the measured values by software
and it works pretty well so far. I didnt made test readings over the full range from 0.15V-3.3V yet.

Regards,
Rick

mnemonix
Posts: 9
Joined: Mon Jan 23, 2017 11:07 pm

Re: Analog READ - Precision?

Postby mnemonix » Tue Jun 06, 2017 10:35 pm

There is some non-linearity in the ADC range, see my post here: viewtopic.php?f=12&t=1045#p4636

As you can see there the linearity is much better with the -0dB and -6dB settings. But there is always a little blind spot near zero.

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