I'm storing in an array the voltage I read from the electrodes, I'm using 256 samples, and then I'm calculating the FFT. I'm repeating that all the time so that I get the actualised BPM. The thing is that if I have to read and store all new 256 it takes more time. I wanted to know if there is a way in which I don't have to do that. I could just read the next voltage value and put it in my Fourier transform (to do that I would have to eliminate the first voltage value I used so that I still have 256 samples). I don't know if I'm making myself clear.