Arduino ADC specifying input range

Development Tools IDE 1.x
1

Hello fellow Arduino'ers!

Is there any way to specify an input range for the ATmega328 ADC?
I.e. if analog input voltage ranges from 3 - 3.5 V is there a way to make 3 V zero and 3.5 V 1024 ?
It seems the ATmega328 only allows for the top limit to be specified through AREF pin, but so far I haven't found a way to "cut off" the lower 3V range.

Does anybody know a way to solve this or a workaround?

Thanks a lot in advance & have a great day!! :slight_smile:
Tom

2

If you want or need full 10 bit resolution range for converting a 3-3.5vdc signal you must use an external op-amp set up to have a -3 volt offset and gain of 10.

Lefty

3

Thanks Lefty, I already thought that either that or an external ADC with min and max input voltage will be required.

I appreciate your help! :slight_smile: