delay() in setup - The delay prevents a task from executing. #214

In the example: Scheduler_example00_Blink.ino

You've coded two delay(x) in the setup function. That adds up to 3 seconds.
However, the scheduler doesn’t start until **ts.execute()** is called in loop().
By that point, more than 3 seconds have passed, but several 500-ms intervals have already elapsed.
The library attempts to catch up on these missed intervals.
This results in rapid function calls.

To measure the time, I modified the blink1CB() function:

bool LED_state = false;
// === 1 =======================================
void blink1CB() {
  static uint8_t Anzahl = 0;
  if ( tBlink1.isFirstIteration() ) {
    _PP(millis());
    _PL(": Blink1 - simple flag driven");
    LED_state = false;
  }
  Anzahl++;                   // number of call 
  // Serial.printf("Aufruf: %u \tbei %ums\n", Anzahl, millis());
  Serial.printf("Call: %u \tat %ums\n", Anzahl, millis());

  if ( LED_state ) {
    LEDOff();
    LED_state = false;
  }
  else {
    LEDOn();
    LED_state = true;
  }

  if ( tBlink1.isLastIteration() ) {
    tBlink2.restartDelayed( 2 * TASK_SECOND );
    LEDOff();
  }
}

Monitor output:
3027: Blink1 - simple flag driven
Call: 1 at 3027ms
Call: 2 at 3027ms
Call: 3 at 3027ms
Call: 4 at 3027ms
Call: 5 at 3027ms
Call: 6 at 3027ms
Call: 7 at 3038ms
Call: 8 at 3501ms
Call: 9 at 4001ms
Call: 10 at 4501ms
Call: 11 at 5001ms
Call: 12 at 5501ms
Call: 13 at 6001ms
Call: 14 at 6501ms
Call: 15 at 7001ms
Call: 16 at 7501ms
Call: 17 at 8001ms
Call: 18 at 8501ms
Call: 19 at 9001ms
Call: 20 at 9501ms

The first 7 function calls occur within 10 ms; after that, everything works as intended every 500 ms.

Solution: Start the task only after initialization (after the delays).
Conclusion:
Task tBlink1(PERIOD1, DURATION / PERIOD1, &blink1CB, &ts, false);

At the end of Setup
tBlink1.enableDelayed(PERIOD1);