How do I code a timer into an if else statement?

Projects Programming
1 
if (distance>10 [for 5 seconds])

{

Console.WriteLine("Distance is greater than 10");

}

How do i code it to only display "Distance is greater than 10" only after it has been greater than 10 for 5 seconds?

edit: thank you all for all your help! greatly appreciated!

2

When distance>10 is true and a Flag variable is reset, set that Flag variable and start your 10sec TIMER.

When distance<=10 reset that Fag variable.

When the Flag variable is set, check the 10sec TIMER, if it has expired, do your stuff.

3

So yeah, pretty much as @LarryD has said.

boolean timerIsStarted = false;
unsigned long startTime = 0;

void loop()
{
  if (distance > 10)
  {
    if (timerIsStarted)
    {
      if (millis() - startTime > 5000)
      {
         // Do the stuff when timer > 5 seconds
      }
    }
    else
    {
      timerIsStarted = true;
      startTime = millis();    
    }
  }
  else
    timerIsStarted = false;
}
4

more compact version with additional comments

void loop(){
  if (distance > 10) {
    if (timerIsStarted == true){ // can be coded shorter as if (timerIsStarted) 
      if (millis() - startTime > 5000) { // check if more than 5000 milliseconds have passed by since distance was > 10
        // if more than 5000 milliseconds HAVE passed by since distance > 10 has begone
        // Do the stuff when timer > 5 seconds
      }
    }
    
    else  { // if distance is > 10 but timer was NOT yet started
      // set flag-variable to true to avoid repeating startTime = millis();
      // we want the BEGINNING of distance > 10 
      timerIsStarted = true; 
      startTime = millis();  // store snapshot of time in that moment WHEN distance STARTED to be > 10
    }
  }
  else // if distance is LESS than 10 
    timerIsStarted = false; // set flag-variable to false to stop time-checking
}

best regards Stefan

5

Sorry... I missed the value you added ( = 0).

6

to stay in your philosophy: here's a short answer. Find out the details yourself

not seeing the value is caused by experts blindness for beginner difficulties

7

The one thing worse is blindness by people that are obsessed with their own ego.

1 Like
8

I like to reverse the test:

  static unsigned long LastTimeDistanceWasLE10 = 0;

  if (distance <= 10)
  {
    LastTimeDistanceWasLE10 = millis();
  }

  if (millis() - LastTimeDistanceWasLE10 >= 5000)
  {
    // Distance has been > 10 for more than 5 seconds
    Console.WriteLine("Distance is greater than 10");
  }
2 Likes
9

In the mean time, should 5-sec timer be stopped if distance becomes < 10?

10

That bit isn't more compact! :wink:

Comparing a Boolean variable to == true adds nothing to the readability of the code, just clutters it.

11

Where do i put the

boolean timerIsStarted = false;
unsigned long startTime = 0;

?

12

They are intended to be global variables, so put them at the top of the code with the other global variables. (Not inside any function, and somewhere before/above where they are used)

13

for a beginner that sees this for the first time it might look odd to her/him if you code

if (timerIsStarted)

I wrote

if (timerIsStarted == true){ // can be coded shorter as if (timerIsStarted)

Your feedback made me think about it. So maybe places vice versa would be better

if (timerIsStarted ) { // a boolean variable does NOT need an explicit comparising if (timerIsStarted == true)

Anyway for a real expert the code could be much more "cluttered" she/he will be able to read and understand quickly just the same as a real expert is able to understand quickly the most compact code that has no comments at all.

Well me myself I'm not a real expert. And I'm not obsessed with my ego. I'm obsessed with writing code for beginners that is easy to understand. And as I'm no longer a beginner but a somehow to some extent advanced C++-user I started to get blind for beginners difficulties myself. It is an unavoidable effect that grows with the knowledge. Then you have to become an advanced user / expert in a second field: the beginners difficulties. And this is the reason why I almost always invite beginners to ask many questions. Because the beginners are the experts about beginners difficulties.

But I guess - for some users - writing such an answer will be seen as
you see he's obsessed with his ego.

best regards Stefan

1 Like
14

Again ?

15

tstbu (idu)

16

:thinking:

#define ENABLED      true
#define DISABLED     false

#define PUSHED       LOW
#define RELEASED     HIGH
. . .

if (timerIs == ENABLED){
17

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.