Method _timerShot

examples/WebCamServer/ESP32Cam.cpp:584–606

* Exclusively get semaphore and repeatedly takes a one-shot image. * The cycle for the timer shot is generated by the hardware timer provided by * the ESP32 module. This function initializes the timer for periodic execution * of the timer interrupt function for taking pictures. * @param period Period to shoot in seconds. * @param filenamePrefix File name for saving the captured imag

 * @param  filenamePrefix File name for saving the captured image.
 */
void ESP32Cam::_timerShot(const unsigned long period, const char* filenamePrefix) {
  if (!period)
    return;

  if (!filenamePrefix)
    filenamePrefix = "/" ESP32CAM_GLOBAL_IDENTIFIER;
  if (!strlen(filenamePrefix))
    filenamePrefix = "/" ESP32CAM_GLOBAL_IDENTIFIER;

  // Save the global variables for the ISR and cancel the timer residue.
  _captureName = filenamePrefix;
  _purgeTimer();

  // Register a task to secure and shoot a hardware timer.
  _hwTimer = timerBegin(ESP32CAM_OCCUPIED_TIMER, getApbFrequency() / 1000000UL, true);
  timerAttachInterrupt(_hwTimer, &ESP32Cam::_timerShotISR, true);
  timerAlarmWrite(_hwTimer, period * 1000000UL, true);

  // Start an alarm
  ESP32Cam_internal::esp32cam = this;
  xSemaphoreGive(ESP32Cam_internal::xMutex);
  timerAlarmEnable(_hwTimer);
}

/**
 * A hardware timer interrupt routine is called when the shooting cycle of the