[time-nuts] uC ADC resolution (was: Poor man's oven)

Bob kb8tq kb8tq at n1k.org
Tue Jun 6 20:04:56 EDT 2017


Hi

You can only get back bits to the degree that the problems are caused by noise. 
If it is 1/F noise, averaging over long periods is going to be really tough.

Bob

> On Jun 6, 2017, at 7:43 PM, Chris Albertson <albertson.chris at gmail.com> wrote:
> 
> On Tue, Jun 6, 2017 at 2:17 PM, Attila Kinali <attila at kinali.ch> wrote:
> 
>> On Tue, 6 Jun 2017 16:37:27 -0400
>> Bob kb8tq <kb8tq at n1k.org> wrote:
>> 
> 
> 
> 
>> . Heck, the STM32F4xx have so much internal noise that the ENOB
>> of their ADC is below 6bit... so low that they even had to write an
>> appnote on how to do averaging to get back to the 12 bits the ADC is
>> spec'ed for. (but don't mention that to an ST sales person, they will
>> hate your guts afterwards).
>> 
> 
> Can you actually get back all of those bits?   How many samples would you
> need?   My current use case for the STM32 ADC is to track battery voltage
> and maybe 6 bits is enough but if I can get to 12 with a software-only fix
> I'll take it.  Batteries volts charge slowly so I'd have time to take many
> samples.   It's a rather mundane application.  Controlling a battery
> powered motor and I can't let theLiPo battery dichange below a limit so I'm
> sampling voltage at 1Hz.   Got a link to or the name of the app note?
> 
>> 
>> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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