Weird IR reciever values

[silo_xtreme]

Hey All,

Anyone know why I would get values in the range of 65533 - 65535 on an ADC measurement?  I only seem to get this on my IR receiver from my ATXMEGA chip.

I've verified that we're not exceeding any electrical characteristics.

I have an interrupt that keeps sampling the ADC pin and updated a variable.

Could I be sampling too fast or something? 

[bsamuels]

Try it with another IR sensor, or another microcontroller and make sure the problem isn't hardware related.

[silo_xtreme]

Heh.  Sorry for not updating this sooner.

The problem is actually cause because the Voltage was too small for the resolution selected on the ADC.

Thanks,

[bo13th]

what type of ADC?

[silo_xtreme]

The Xmega128A1 ADC.

For some reason it was not resolving values less than 1.7 ma. 

[Admin]

The Xmega128A1 ADC.

For some reason it was not resolving values less than 1.7 ma. 

ma or mV?

Is it 10 bit ADC?

[silo_xtreme]

mV ... Yes, 10 bit.  It ends up being a moot problem since I don't need to filter out ambient light in the s/w ... We have a hardware filter on it

[Admin]

Well

5V/(2^10 bit) = 0.0049 V

or 4.9mV

So getting 1.7mV resolution with a 10 bit system is impossible

. . . well, unless you are making assumptions based on a timer in a dynamic system . . .

[silo_xtreme]

Doh!  Now that is good to remember! Thanks.