Goertzel

main.c

Goertzel(float TARGET_FREQUENCY,float BLOCK,float SAMPLING_FREQ){
  SAMPLING_RATE=SAMPLING_FREQ;  //9KHz for a 16MHz Arduino
  TARGET=TARGET_FREQUENCY; //must be an integer of SAMPLING_RATE/N
  N=BLOCK;  //Block size
  int k;
  float omega;

  //math
  k = (int) (N * (TARGET_FREQUENCY / SAMPLING_RATE) + 0.93);
  omega = (2.0 * PI * k) / N;
  sine = sin(omega);
  cosine = cos(omega);
  coeff = 2.0 * cosine;

  ResetGoertzel();
}