Reading a li-ion with a 1v adc

[solexious]

Hello all,

I'm trying to read the voltage of my power source for my esp8266 with its inbuilt adc. Ideally I want to use as full of the 0-1v range of it's adc so a simple voltage divider doesn't seem to be the answer to my problem.

Is there a better technique for reading 2.8-4.3v with a 0-1v adc?

Cheers

Sol

[jeroen79]

Why would a voltagedivider not work?
Just scale it down so that the max input is less than 1V and then scale it back up in the software.

[solexious]

Why would a voltagedivider not work?
Just scale it down so that the max input is less than 1V and then scale it back up in the software.

I would if I was wanting to read 0-4.3v but ideally I want to use the adc's full range to read 2.8-4.2v rather than lose resolution scaling it up in software.

[jeroen79]

Put a zener diode between the + and the voltage divider to take 2.x V off the battery voltage.

[hamdi.tn]

one option is to use basic opamp circuit and a couple of resistances will do that for you ... subtract Vbat  - 2.8V with a differential than apply that to a voltage divider of 1/1.4
second, if you can change the negative voltage reference of the adc, then move it up to 2.8V and scale down your Vbat by 1/1.4