Countdown timer with potentiometer

[StefanL38]

@edichumo

after putting in my potentiometer code i still got the same repetitive blinking. I don`t want the LED to blink, I want it to stay ON until time elapses and then go OFF. it MUST NOT come ON a second time. just once , like an alarm clock

Have you read what I posted in post #7 Countdown timer with potentiometer - #7 by StefanL38

@StefanL38

if (countDownStarted) {
  if(Timing-condition) 
      switch off
     countDownStarted = false;

On an alarm-clock you have a state-change from

• alarm-time not (yet) reached
  to
• alarm-time reached

what is your state-change that makes your code know:
the count-down time starts here

= switch on LED and from now on
and in 30 min. 1h, 2h in the future switch LED off

You could use the potentiometers value that changes from beeing outside the range

(potVal > 300 && potVal <= 500)

to be inside this range. But this would mean:
Your code is running very very fast as soon as you enter the range 300-500 this would be taken as the trigger.
You would not be able to choose a value

So there must be something additional that is used as the trigger to say
the count-down time starts here

My suggestion: a button press.

best regards Stefan