issues on ESP32 under heavy load (watchdog + endless loop)

[Jeronimo59]

Hello,

Thank you for this useful library.

When using it on a "heavy loaded" ESP32-S3, I experienced watchdog timer (WDT) issues, suggesting a loop task was running for too long.

After some investigation, I found that delay(0) was not yielding, so I solved the issue by replacing

      delay(0);

by

      vTaskDelay(1);

in the following functions:

DFRobotDFPlayerMini::sendStack()
DFRobotDFPlayerMini::waitAvailable(unsigned long duration)
DFRobotDFPlayerMini::available()

I also came across situation where DFRobotDFPlayerMini::sendStack() whould be stuck in endless loop, so I replaced in

      while (_isSending)

by

      long timeout = millis() + 1000; // wait no more than 1000 ms
      while (_isSending && millis() < timeout)

I found those changes to make the library more robust in my context.

HTH