Counter

Using Arduino Programming Questions
1

Hi all.
i need to do a counter, ex:
if (buttonState == HIGH) {
// turn LED on:
digitalWrite(ledPin, HIGH);
for 5 minutes.

I need reverse counting

2

Take a look at millis - that'll help you establish how much time has passed.

3

i not need to now how much time has passed. i need to do for 5 minutes.

4

sinsetsin:
i not need to now how much time has passed. i need to do for 5 minutes.

Rubbish.
You need to know that 5 minutes has passed

Look at Using millis() for timing. A beginners guide, and look at the BlinkWithoutDelay example in the IDE.

5

Indeed rubbish. If you're counting, how do you know how much time has passed if you don't know how long each count takes?

6

So you need to turn the LED on then 5 minutes later turn it off. The way you know when to turn it off is to check the time until you know that 5 minutes has passed.

If you really don't need the Arduino to be doing anything else at all for that 5 minutes you can use delay() to do the checking for you.

    digitalWrite(ledPin, HIGH);
    delay(300000);  // do nothing for 5 minutes
    digitalWrite(ledPin, LOW);

But it's usually better to use millis(). You can use that to time things without completely stopping everything else from working.

Steve

7

Thank you for help. You are very nice.