Newbie Coding Problem... argh!! Help Please!

Hi all,
I have written some code but when i test it, it doen’t work as i would like it to work.
Here is the code:

int cutdownPin = 10; // Pin linked to Cutdown
int x = 0; // X is for Cutdown timer

void setup()
  pinMode (cutdownPin, OUTPUT);

void loop()
  while (x < 15) 

  if (x >= 10 && x <= 15) // Time Zone for cutdown
    digitalWrite (cutdownPin, HIGH);


I want the led to turn on at 10 secs but it turns on at 15?? Why is this?
Also when i implement an “else” statement after the last if for

else {
digitalWrite (cutdownPin, LOW)

it doesn’t turn the led off after 15 secs instead it stays off all the time?
Help would be much appreciated,
Many Thanks :slight_smile:

I want the led to turn on at 10 secs but it turns on at 15?? Why is this?


  while (x < 15)

Correct me if I’m wrong, but it looks like you want a delay of ten seconds, then turn the LED on for 5 seconds, then off?

So, why not write it like that?

delay (10 * 1000);
digitalWrite (LEDpin, HIGH);
delay (5 * 1000);
digitalWrite (LEDpin, LOW);

Thanks! That is what i want to do.

But, I also want to have another "loop" running at the same time sending gps data. For testing i set the time to 10secs and 15secs but in the real thing it will be 3 hours, so if i had a delay then that would delay sending data aswell? Is there a way to have two loops running side by side? Many thanks :)

If you have a "delay", yes, you stop other stuff running as well.

Think about how you yourself would perform a task like this.

Look at the clock ("millis()"), and note the time. Has ten seconds gone by? ie. Is "millis" now > (the time I noted PLUS ten seconds' worth of milliseconds)?

No? Ok just carry on. Have another look at the clock, whatever. Yes (tens seconds has elapsed) - do what you have to do after ten seconds.


startTime = millis();
if (millis () > (startTime + (10* 1000))
  {turn your LED on}

VERY IMPORTANT: Remember : as soon as "loop" has finished, it gets called again, so be careful about not over-writing your "startTime" AND "delay" blocks everything else from happening.

FANTASTIC! Thanks for the great help :)