[Tinyos-2.0wg] Concerns about ADC in 0.1mV

[Philip Levis]

On Jul 26, 2006, at 4:45 PM, Prabal Dutta wrote:

> I think the real problem is making sure you know the value of Vref
> used for the A/D conversion.  If Vref is static, then that's great and
> an ADC count will suffice.  However, if Vref can change, then the
> conversion factor needs to be sent along with the ADC counts.  This
> approach allows engineering units to be recovered from the data and
> also minimizes conversion computation on the mote.  However, it might
> (a) not be supported in all platforms (if Vref can't be compared to a
> bandgap reference) and (b) could require two ADC conversions -- one
> for the signal and one for Vref.
>
> - Prabal

This was the point I was trying to (incoherently) make during the  
telecon. A voltage is not meaningful without a voltage reference.

Phil