stimav4: getSDFromUV bug for slow wind

[pat1]

La funzione:

void ElaborateDataTask::getSDFromUV(float u, float v, float *speed, float *direction)
{
  *speed = sqrt(u * u + v * v);
  *direction = RAD_TO_DEG * atan2(-u, -v);
  int16_t tmp_dir = round(*direction);
  if(tmp_dir < 0) tmp_dir += 360;
  *direction = tmp_dir % 360;
  if(*speed < CALM_WIND_MAX_MED_VECT) {
    *speed = 0;
    *direction = 0;
  } else if (*direction == 0) {
    *direction = WIND_DIRECTION_MAX; // Translate 0 -> 360 (WIND_DIRECTION_MAX)
  }
}

manca del test per intensità molto basse o zero
Il test è necessario per evitare errori di troncamento successivi
e fondamentalmente perchè atan2(0,0) ha risultato indefinito

Questa la versione corretta:

void getSDFromUV (float u, float v, uint16_t *speed, uint16_t *direction) {

  if (abs(u) < CALM_WIND_MAX_MS*100 && abs(v) < CALM_WIND_MAX_MS*100){
    *speed = 0;
    *direction = 0;
  } else{
  *speed = round(sqrt(u*u + v*v));
  *direction = round(RAD_TO_DEG * atan2(-u, -v));
  *direction = *direction % 360;
  }

[digitecomg]

Inserito check su limite ATAN2