[sdiy] A/D weirdness

[Karl Ekdahl]

Hi list, got some trouble with an A/D converter and wanted you guyses thoughts.

I'm working with a ADS8326 16-bit super nice converter but i keep getting erratic results, the data i get back fluctuates ~+-100 bytes (so app. 7 bits) which is clearly way out of range for this converter. While testing i've been tying both inputs to GND to try and minimize the variables, i've tried both buffered and unbuffered signals. The only way i've gotten non-erratic results so far was to tie the "ref"-input to GND so i figured it might be the voltage reference. However whatever i've tried (buffered through opamp, unbuffered etc.) i get the same results - also this reference (a REF5050 divided to 2.5V as the ADS8326 is running on 3.3V) is driving a D/A that works just great so i guess this is not the problem. I did for a while have some issues with not getting the lower bits in due to accidentally over-clocking the A/D, however i put in a delay that fixed that issue. I tried putting in various delays in the code but to no avail.

So i'm stumped, any help greatly appreciated.

Karl