Best practice: using digitalWrite in a while loop

Projects Programming
1

when analogRead V2_GPIO is more than 15 i need to blink LED and also M3_NPN should be HIGH all the time
otherwise M3_NPN should be low

is it good way to call digitalWrite(M3_NPN, LOW); or digitalWrite(M3_NPN, HIGH); all the time or not.

which of examples is best way or there is better way

Example 1:

void loop(){
      while (analogRead(V2_GPIO) > 15) {  
        digitalWrite(M3_NPN, HIGH); 

        digitalWrite(L3_NPN_led, LOW);
        delay(100);
        digitalWrite(L3_NPN_led, HIGH);
        delay(100);
       }

      digitalWrite(M3_NPN, LOW);
  delay(100);
}

Example 2:

  if (analogRead(V2_GPIO) > 15) {
    digitalWrite(M3_NPN, HIGH); // Keep M3_NPN high
      while (analogRead(V2_GPIO) > 15) {  
        digitalWrite(L3_NPN_led, LOW);
        delay(100);
        digitalWrite(L3_NPN_led, HIGH);
        delay(100);
     }
    digitalWrite(M3_NPN, LOW); // Keep M3_NPN low
  }
2

At a glance, there is no substantive difference between the two. Convince yourself - put your finger on either, they will function identically.

Oh, yes, yes there is.

Your both examples block, that is to say you are stuck in the while loop blinking, meaning any other activity (reading inputs, doing calculations, adjusting outputs, e.g.) is impossible.

We like to let the loop() do the looping. In this case it would mean reading the analog input every time through you loop() function, and with that reading decide whether or not to advance the progress of a pattern that blinks without the use of delay.

And whether to turn on or off M#_NPN

  digitalWrite(M3_NPN, HIGH); // Keep M3_NPN high

So it should be no surprise that I next direct your attention to an idea called "blink without delay" - there is an example in the IDE, and a competent enough article if you google

 arduino blink without delay

but TBH there are dozens of places to see the same idea, and since it is a bit tricky everyone likes to think she has come up with a superior introduction to the concept. Googling will turn up plenty of various points of view.

Read a few of them, see if something catches hold of you. There is an Aha! moment.

a7