I have just one easy question - will a small negative voltage on the analog input damage the Arduino board (Mega 2560)?
My project involves reading some volages from a measuring circuit, and sometimes (when the measured device operates at a higher frequency than the op-amp in the circuit can handle accurately), about -10mV to -15mV appears on the analog input. Is this a problem for the board?
Shouldn't be a problem. The negative spec is -.5 below ground I believe. That's when the internal negative clamping diode will start to conduct and it can only handle a small amount of current. So -10 - -15 mv should not be a problem in my opinion.