I am planning on simple program which flashes an LED to the beat of music. It is going to use a 3.5mm audio jack plus an opamp, voltage divider, etc. to have an input of 2.5v +/-2.5v. I have read that while FFT gives you the amplitudes of the bins of the whole spectrum of the audio input, Goertzel's algorithm -which gives you the amplitude of just one completely customizable bin- sounds like it would fit my needs best.
I would greatly appreciate it if someone could walk me through an implementation of Goertzel's algorithm, assuming I have my 2.5v +/- 2.5v audio source connected to A0 analog input pin, and an LED on PWM pin 13 and that I want the LED on pin 13 to correspond to the amplitude of the 0-64Hz range of the audio input.