subroutines

Using Arduino Programming Questions
1

Hi,
I'm new here and also new in programming arduino.
First project I started is a small home control system.
I want to program a subroutine for an time relay.
When I put the commands in the void loop, everything is working except that the output comes high after reset.
When i put the same commands in a subroutine, the output stays high after pushing the buttom ones.

int drukknop = 22;
int LED = 13;
long starttijd;

void setup()
{
  pinMode(LED,OUTPUT);
  pinMode(drukknop,INPUT);
  //digitalWrite(LED,LOW);
}

void loop()
{
    if (digitalRead (drukknop) == LOW) {
        starttijd = millis();
        tijdrelais();
            }
}
 
void tijdrelais()
{
 if ((millis()- starttijd) < 2000){digitalWrite (LED,HIGH);}
         else {digitalWrite (LED,LOW);
}
}

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2

Schematic?

3

what do you mean ?

I want that after pushing the button, the output wil stay high during 5 minutes and then commes low again. (in the test it is 2 sec).

4

I want to see what you have got wired and how it is wired.
That is a schematic (circuit diagram).

5

only digital pin 22 is wired with a push button between ground and input and a pull up resistor of 1 K to 5V
The board is detecting the change of the button that's not the problem.

6

Vin: 5V---*
|

R 1 K
/
|
|
22----*
|
|
| push button
|
|
|
*----> Ground

7

You only call tijdrelais when the button is pressed. Move it out of the body of the if.

8

thanks. It's working

9

the only problem is that after reset op the arduino. The relay is going on for the programmed time. Why, I don't know because I force him low in the setup.

char drukknop = 22;
char LED = 13;
long starttijd;

void setup()
{
pinMode(LED,OUTPUT);
pinMode(drukknop,INPUT);
digitalWrite(LED,LOW);
}

void loop()
{
if (digitalRead (drukknop) == LOW) {
starttijd = millis();
}
tijdrelais();
}

void tijdrelais()
{
if ((millis()- starttijd) < 10000)
digitalWrite (LED,HIGH);
else
digitalWrite (LED,LOW);
}

10

It's because when you reset the arduino, millis is zero and so for the first ten seconds, this will be less than 10000:

(millis()- starttijd

One way to solve it is to turn the relay on when you detect the button press and use your subroutine to turn it off when millis()- starttijd is greater than 10K

11

thanks