If you used a divider with a 1 k at top 3.9 k bottom and 1 k to adc you should get good results
On Thu, Oct 28, 2010 at 9:05 AM, Sebastien Lelong < [email protected]> wrote: > > 2010/10/28 Oliver Seitz <[email protected]> > >> >> Good thinking, but check the datasheet, I think the ADC doesn't work well >> with Vref lower than about 3V. >> > > Right, it seems hardware limitations are: > > - Vref+ - Vref- > 2V > - Vref+ > Vdd - 2.5V (so Vref+ > 2.5V since PIC is powered at 5V) > - VRef- < 2V > > I wouldn't use Vref- (Vss instead), so Vref+ would have to be between > [2.5V, 5V]. > > Internal voltage generator, according to 16F88's datasheet (page 127, when > CVRR=0), won't output more than (1/4 * 5) + (1/2 * 5) = 3.75V (it also > mentioned 0.72 * CVRSRC ~ 3.6V). I guess it's possible to bring this up to > 5V. > > Cheers > Seb > > -- > You received this message because you are subscribed to the Google Groups > "jallib" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<jallib%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/jallib?hl=en. > -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
