Please note: Friday June 18 is a holiday celebrating Juneteenth, please allow extra time for your order to arrive and plan accordingly.
0

ADC readings off on Itsy Bitsy M4
Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.

Re: ADC readings off on Itsy Bitsy M4

by Bekar_T on Thu May 06, 2021 3:54 am

Nope, actually, cancel that.

2% is an expression of the sum of ADC and DAC errors. ADC alone has a very consistent 5% error when readings are taken in reference with the external source.

I'm assuming I'll find a DAC error to be about 3% and "in an opposite direction", resulting in 2% net error when they are tied with a jumper wire.

If that can't be addressed at least to some extent, I think it should at least mentioned somewhere because when a description says:

Dual 1 MSPS 12 bit true analog DAC
Dual 1 MSPS 12 bit ADC

A beginner like myself (who, as we've established, these boards are targeted at) would not assume there could be an unspoken assumption that 5% error in readings is not an odd thing to happen.

Bekar_T
 
Posts: 22
Joined: Wed Apr 21, 2021 12:41 am

Re: ADC readings off on Itsy Bitsy M4

by Bekar_T on Thu May 06, 2021 4:56 am

Wellp, now I'm confused.

DAC output has barely 0.5% error when measured independently.

So main source of error is ADC and it varies A LOT depending on . . . I don't know what.

Does this mean that even if I go through the labors of calibrating and compensating for the error in ADC, it will still need adjusting in every specific circuit configuration?

Bekar_T
 
Posts: 22
Joined: Wed Apr 21, 2021 12:41 am

Please be positive and constructive with your questions and comments.