Arduino – Lecture d’une donnée à intervalle régulier

unsigned long lastTime = 0;
unsigned long currentTime;

const int readPeriod = 900000; //each 15 mn

void readDatas()
{
  currentTime = millis();

  if (currentTime == 0)
  {
    lastTime = 0;
  }

  if (lastTime == 0 || (currentTime - lastTime) > readPeriod)
  {
    lastTime = currentTime;

    // read datas ...
  }
}

void loop()
{
  ...

  readDatas();

  ...
}