From: Dave Hylands <dhylands@gm...> - 2008-10-23 05:20:20
On Wed, Oct 22, 2008 at 8:39 PM, <amey0821@...> wrote:
> Hi dave, i checked the voltage across all of the regulators and they are all 5V, but the voltage across the ADC pins is now around 2.8V.
If the ADC pins are configured as inputs, then the voltage on the pins
will essentially be random unless something is connected.
> The problem with the robostix flash was that i forgot to put S10robostix in /etc/init.d ... remedied thanks.
> big problem with the ADC tho, flight trials were going really well and my thesis is due in a week, this is devastating!
> I did a basic test with your i2c-io program
> i2c-io 0x0b setdir f.0 in
> i2c-io 0x0b get adc.0
> with no sensor plugged in (i.e no voltage to adc.0 pin) i am getting ~400 reading from i2c-io, as soon as i plug the sensor in it goes to zero. With the sensor plugged in, when i read the voltage across the avcc and ground it reads about 1.4V and between adc.0 pin and ground it reads at about 0.2v which should be picked up by the ADC.
With no sensor plugged in, the input will be floating, so the value
you get back is no reliable.
Try connecting the input signal to ground and then read it, and
connect the input signal to AVCC and then read it. If those are
working fine, then the fault lies with the sensor itself.
With the sensor hooked up, what voltage are you seeing?
I'm assuming that you're connecting the ground pin from the robostix
to the ground pin on the sensor (without common grounds, none of the
voltages make any sense).
The ADC inputs also assume that the sensor has a low-impedance output.
If the impedance is too high, then this will also cause weird
Shuswap, BC, Canada