[Gumstix-users] ADC sampling rate and

[sudil <su...@gm...>]

I am using Gumstix overo 2.6.36 ADCs for reading analog signal. I used the
code shown here http://wiki.gumstix.org/index.php?title=ADC_overo_2.6.38-
for testing. 
I am modified the code just with 100 loops and gave 5 Hz sinosoidal signal
to pin 2-7 separately with ground at AGND. Amplitude of the signal varies
from 500 mV to 250 mV. But I am having strange problem with this as shown in
this figure. http://old.nabble.com/file/p32807936/adc.jpg adc.jpg 

1. As you can see, I am getting the signal only in channel 2, but this has a
kind of gain (max amplitude is ~1V instead of 500mV). while other channels
are almost useless. 

2. The sampling rate is very less than expected (< 100 samples/s). I need
around 10 times more.

3. Even if I dont give any signal, I get fluctation on ADC's of around 0.2 -
0.5 V.

I need help in this issues because I can't move on without this. 
Here is the code i used:  http://old.nabble.com/file/p32807936/adc.c adc.c 

Thank you.




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