message: fix valgrind
diff: @@ -136,8 +136,8 @@ void SyntheticBoard::read_thread ()
  {
  // predefined sin wave for exg
  unsigned char counter = 0;
  - constexpr int num_samples = 250;
  - float base_wave[256];
  + constexpr int num_samples = 256;
  + float base_wave[num_samples];
  double amplitude = 1000.0;
  double noise = 0.6;
  double shift = 0.3;
  