Band Pass filter output data

Your output doesn't look right.

your input swings between 0 and 243, yet your output is of +160,000 order with repeated close values.It doesn't look you have done any bit truncations.

Go to matlab and type:

h = < your above coefficients>;

x = <your input vector>;

now apply filter:

y = filter(h,1,x); you should check your results against this as reference

I got an initial y values of +80 followed by +4