Yes, Vref is the battery voltage. I think you might be able to switch the ADC to the internal ref but it won't do you much good because it's 2.5v or something. But setting a very low ref voltage probably won't help due to noise anyway.
The ATMEGA has an option to use differential inputs and set a x200 gain which might do your trick for you, but I don't know of any TOS impl for it so you'll have to go rummage though the spec-sheet to figure it out. I just looked and it doesn't seem to be the most obvious thing in the manual... Or you could use an opamp to pre-condition your input. Most likely with sub-milli-volt signals (EEG electrodes?) you'd want a pretty good well isolated amp in front of your converter anyway. MS [EMAIL PROTECTED] wrote:
the actual ADC reference on Mica2 is the supply voltage (3.3 V),isnt it?. Is it posibble to change this reference value, without mayor hardware changes. Cuase I wanted to measure voltages in the order of milivolts and I am thinking in a reference voltage like 10 mV. What would be the answer in Tmote platform?? thanks. -Bill _______________________________________________ Tinyos-help mailing list [email protected] https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
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