AVR-Chat

I tried it with both axis, and I've unbiased my signal. One axis works 
fantastically; the other does not.
Gustavo

Jim Wagner wrote:
>
> On Sat, 08 Sep 2007 03:11:18 -0400
> Gustavo Goretkin <gustavo@goretkin.com 
> <mailto:gustavo%40goretkin.com>> wrote:
> > Hi,
> > I'm running some code on an ATMega32 (PDIP, 16mHz) I'm
> > using 4 of the 8
> > ADC channels to collect data from sensors (gyros and
> > accelerometers).
> > These are channels 1,2,3,4 (channels from 0-7). I am, in
> > reality, using
> > only channel 1,3,4 (plan to add a sensor connected to 2
> > soon). Channels
> > 1 and 3 receive very accurate data, but for some reason
> > channel 4's data
> > is always off. For example, I'm using a two-axis accel.
> > connected to
> > channels 3 and 4. After I average 3 and 4's values for a
> > while to get
> > the bias of the accelerometer's outputs, 3 always returns
> > a value of
> > zero (after removing the bias and having the sensor
> > still), but 4 always
> > returns some random value that is anywhere from 15-30 ADC
> > units off. I
> > have switched the sensor configuration (swapped 3 and 4),
> > and still 4
> > returns non-ideal values and 3 is fine. I have read of
> > problems on the
> > ATMega 128 with JTAG on the first four pins of Port A,
> > but Port A's
> > alternate function on the ATMega 32 is ADC only. Is there
> > something I am
> > missing?
> >
> > Thanks.
> > Gustavo Goretkin
>
> Is the axis with steady signal the Z axis, perhaps? If it
> is, you are just measuring gravity?
>
> Jim
>
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