Temporize is posible?

Projects Programming
1

Hello!

Anyone knows how to temporize an action? I want that if a temperature is less then "x" to do something (just some digital outs) but no more than "y" minutes. How could I do this?
Thank you!

2

Lots of ways to do that. Some better than others.

if(temp < x)
{
   digitalWrite(somePin, HIGH);
   delay(y * 60 * 1000UL);
      digitalWrite(somePin, LOW);
}

is one way. Not a very good one.

if(someTime == 0)
{
   if(temp < x)
   {
      digitalWrite(somePin, HIGH);
      someTime = millis();
   }
}

if(millis() - someTime > y * 60 * 1000UL)
{
   digitalWrite(somePin, LOW);
   someTime = 0;
}

is another way that is more responsive..

There is the TimeAlarm library, too, that provides a third way. Turn the pin on, set an alarm, with callback. When called back, turn the pin off.

3

Thank you!
I'll study how TimeAlarm library works.
The solution with delay() is the worst! This means that the program is "stuck" there for a long time and can't "read" what temperature I have. The solution with "milis()" looks fine, but I have 2 questions:
I. What does "1000UL" mean??
II. Could I use, in the same sketch, more then one interval independently?

4

I. What does "1000UL" mean??

The 1000 part should be pretty obvious. There are 1000 milliseconds in a second. The UL on the end tells the compiler to treat the value as an unsigned long. Without that, the 60 * 1000 part would be stored in an int sized register, which would overflow. With it, the 60 * 1000 result is stored in a long register, which is the proper size.

II. Could I use, in the same sketch, more then one interval independently?

Absolutely.

5

Ok!
Thank you very much Paul!