core32 ain resolution

[ultra]

here's a question i haven't been able to find documented anywhere: what is the ain resolution for the core32?

thanks,

ultra

[nILS]

12bits

[baptistou]

I think it's 12 bits but I haven't tried it yet, I should do that by the end of the week.

I think also that as the Core32 is powered by 3.3V the AIN range is from 0 to 3.3v can anybody confirm?

Then I heard somewhere that its easy to get jitter (12 bits resolution on a 3.3V range means 0,8 millivolts steps) and to avoid this it's better to uses shielded cables between the pots and the AINs, and between the AIN and the core, or to reduce at maximum the wire distances.

Baptistou

[baptistou]

nILS you are quicker than me for pressing post! :thumbsup:

Edited November 26, 2009 by baptistou

[philetaylor]

I have had quite a few jitter problems using USB power and unshielded cables so yes I would definately recommend using shielded cable and external power.

If you are using an AINX4 then I believe that the range is 0-5V but don't quote me on that!

The latest updates that TK has done have helped to reduce jitter by setting an idle threshold.

Cheers

Phil

[seppoman]

If you are using an AINX4 then I believe that the range is 0-5V but don't quote me on that!

I think that's not right, the AIN uses analog multiplexers that only do routing but don't change the voltage levels. The STM32 runs at 3.3V and usually an ADC can't make sense on voltages that are beyond its supply rails. Probably you can't damage anything by applying 5V but everything above 3.3V will read as max value.

S

[philetaylor]

You qre quite right.... From the core_stm32 page:

• ADCs cannot be supplied at 5V, 3.3V is the limit. This increases the signal/noise ratio

Cheers

Phil

[bilderbuchi]

shouldn't this _decrease_ the SN ratio? i.e. noise gets stronger? :yes:

Edited November 27, 2009 by bilderbuchi

[TK.]

shouldn't this _decrease_ the SN ratio? i.e. noise gets stronger? :yes:

Of course! Thanks! :)

Best Regards, Thorsten.