[time-nuts] Poor man's oven

Adrian Godwin artgodwin at gmail.com
Tue Jun 6 12:13:33 EDT 2017


The specs for the ADC are pretty vague : most of the errors are around 2
LSB but all are quoted with vref at 4V. If you reduce vref (there's an
internal option of 1.1V) you'll increase gain but some of those errors are
going to stay physically the same. In general, I'd tend expect to get more
precision but also more noise. Averaging may help a bit.


On Tue, Jun 6, 2017 at 3:00 PM, Riley, Ian C CTR NSWC Philadelphia, 515 <
Ian.Riley.ctr at navy.mil> wrote:

> Chris,
>
> > The trick with using a uP and it's built-in A/D converters is scale.  You
> > want the limited 10-bits of revolution to fall over the operating range
> > which is very narrow, like 1C.   Anything outside of that is either 0000
> or
> > 1111 and only seen at start-up.,  So at start up the the controller is on
> > "bang-bang" mode then later you have milli-degree resolution over your 1C
> > range.   Basically you are measuring noise. but your $2 uP can take
> 100,000
> > measurments per second and putt tour a digital filter.
>
> I have seen but not used the AREF pins on Arduino and similar uPs; as you
> lower AREF, do you lose any sort of accuracy? Is there a practical minimum
> for what voltage you can feed into AREF?
>
> -Ian R.
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