Min i/p voltage ADC of arduino MEGA

Dear all, what is the minimun voltage the arduino can read to the ADC? Can it read from 3mV to 4mV??

tnx

It depends upon the range of your signal. If you select the internal 1.1V reference voltage then in the 10-bit resolution you have (1024 steps) each bit represents 1.1V/1024 = 1.07mV. That's the theory. In reality, the 1.1V reference voltage is anywhere from 1.0V-1.2V, and the 10-bit resolution does not mean you get 10-bit accuracy. The absolute accuracy is typically about 2-3 LSB's (i.e., anywhere from +/-3.21mV off the actual reading) but worst-case accuracy is not specified.

Generally, reading voltages down in the 3mV-4mV range needs to be done by a carefully-designed external ADC circuit. The A/D converters built into microcontrollers are not designed for this kind of thing.

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My min volt is 1.8mV to 4.1mV. I tried amplifying it to 5V but I just burned everything!!SHIT!!!!

I dont know why this haappend!!(I dont think i had any shorts)

RuggedCircuits: It depends upon the range of your signal. If you select the internal 1.1V reference voltage...

Hey! I really needed that information, I didn't know it was available. Where do I find... here! http://www.arduino.cc/en/Reference/AnalogReference

Is there anything else to be aware of than the possibly bad reference? Quote: "Note After changing the analog reference, the first few readings from analogRead() may not be accurate. "

Apparently it changes all channels at the same time?

Thanks!!!!!!!

Cheers, Kari

[quote author=Daniel Formosa link=topic=55568.msg398334#msg398334 date=1300309388] My min volt is 1.8mV to 4.1mV. I tried amplifying it to 5V but I just burned everything!!SHIT!!!!

I dont know why this haappend!!(I dont think i had any shorts) [/quote]

Burning everything usually means shorts. Can you post your wiring drawing and let us see what you tried to build.

Lefty