Congratulation, you did your first step with data acquisition.
alitarraf:
So my question is how to minimize the noise variance, to have a better signal to noise ratio?
Applying an FFT on the data collected is showing a low frequency noise ~0.01-0.03Hz.
What software calculates fft? Your peaks, in 0.01-0.03 likely to be windowing problem, what kind of windowing you apply?
Printing data over serial one by one isn't gonna to work above 10 samples / sec. Especially with low serial baud rate, increase to 115200 at least. To get correct fft results, you must acquire samples precisely in timing, there are libraries TimerOne or MsTimer2 that could help you to run "results = ads.readADC_Differential_0_1(); " periodically, let say 500 Hz, but you have to define a sampling array, store data to this array and print it to PC ones it finish.