Implementation of FIR and IIR Filters using Arduino

No, that would be a terrible filter. You need different coefficients for the x and y components.

You also can't have a scalar variable called y as well as a vector (array) called y[].

output = y[i]*w[i] + x[i]*v[i];

Don't forget to save output into the correct location in the y[] array.

The other problem with this simplistic code is that it assumes you're always storing values from 0 to LEN, whereas a real filter implementation would have to treat the vectors as circular buffers.