implementing bandpass filtering from an analog audio input

I'm trying to create a bandpass filter (0.5-1 kHz) digitally on the arduino, and this input will drive a dc motor if the frequency of the input sound is within the range.

Thanks.

Have got anywhere? Or do you want to know where to start?

Perhaps: https://www-users.cs.york.ac.uk/~fisher/mkfilter/trad.html

Note that floating point can be very slow, fixed point arithmetic might be worthwhile.

Look at:-

DSP filter code designer