ISR_Timer callback function is not getting called

[khoih-prog]

ISR_Timer callback function is not getting called

[khoih-prog]

You comment them out and disable the TimerHandler

//ESP8266Timer ITimer;
...
// if (ITimer.attachInterruptInterval(TIMER_INTERVAL_MS1 * 1000, TimerHandler))
// Serial.println("Starting ITimer1 OK, millis() = " + String(millis()));

[rohitranjan1991]

can you please elaborate as to what should i be doing to fix the above code ?

[khoih-prog]

I suggest you restart with a simplest example Argument_None and try to understand it before going forward. Then compare the differences between the usages.
Then you'll find out why. This way it'll be more beneficial for you in the future, especially when using the ISR-based features.