Declare a time check function.

Projects Programming
1

Hi guys,

For simplicity consider a rather simple state machine with a button and LEDs: A single button press should light up an LED and after a specific ammount of time the LED should automatically turn off. In fact this works if I write the condition in the loop() like this:

if (millis()-t1>=timeLimit){          
    digitalWrite(L1,0);
  }
  if (millis()-t2>=timeLimit){          
    digitalWrite(L2,0);
  }
  if (millis()-t3>=timeLimit){          
    digitalWrite(L3,0);
  }

t1, t2, and t3 are assigned the sketch uptime 'millis()' at the time the button was pressed.

I want to declare a function just to reduce the size of my loop() function. I tried to declare this function:

void timeCheck()
{
  millis();
  if (millis()-t1>=timeLimit){          
    digitalWrite(L1,0);
  }
  if (millis()-t2>=timeLimit){          
    digitalWrite(L2,0);
  }
  if (millis()-t3>=timeLimit){          
    digitalWrite(L3,0);
  }
}

and call it in the loop() function, but by doing so, the LEDs won't light up.

Any ideas on what I'm missing or doing wrong?

Thanks for your help.

2

Let's see all your code.

.

3

LarryD:
Let's see all your code.

Sure. Here it is:

int buttonPIN=2; //Button

int L1=6; //LED 1
int L2=5; // LED 2
int L3=4; // LED 3

int buttonPushCounter = 0;   
int buttonState = 0;         
int lastButtonState = 0;


unsigned long t1=0; 
unsigned long t2=0; 
unsigned long t3=0;
unsigned long timeLimit = 2500; //The time after each LED should turn off


void setup()  
{
  pinMode(L1, OUTPUT);
  pinMode(L2, OUTPUT);
  pinMode(L3, OUTPUT);
  pinMode(buttonPIN, INPUT);

}



void loop() 
{
  buttonState = digitalRead(buttonPIN);

  if (buttonState == 1 && lastButtonState==0) 
  {
    buttonPushCounter++;
    switch(buttonPushCounter)
    {
    case 1:
      digitalWrite(L1,1);
      t1=millis();
      break;

    case 2:
      digitalWrite(L2,1);
      t2=millis();
      break;

    case 3:
      digitalWrite(L3,1);
      t3=millis();
      buttonPushCounter=0;
      break;
    }
  }

  lastButtonState = buttonState;
  
  if (millis()-t1>=timeLimit)
  {          
    digitalWrite(L1,0);
  }
  if (millis()-t2>=timeLimit)
  {          
    digitalWrite(L2,0);
  }
  if (millis()-t3>=timeLimit)
  {          
    digitalWrite(L3,0);
  }
}
4

pinMode(buttonPIN, INPUT);
Change to:
pinMode(buttonPIN, INPUT_PULLUP);

BTW
Instead of
if (buttonState == 1 && lastButtonState==0)
Use:
if (buttonState == HIGH && lastButtonState==LOW)

Instead of
int buttonPIN = 2; //Button
int L1=6; //LED 1
int L2=5; // LED 2
int L3=4; // LED 3
Use:
const byte buttonPIN = 2; //Button
const byte L1=6; //LED 1
const byte L2=5; // LED 2
const byte L3=4; // LED 3
.

5

LarryD:
pinMode(buttonPIN, INPUT);
Change to:
pinMode(buttonPIN, INPUT_PULLUP);

BTW
Instead of
if (buttonState == 1 && lastButtonState==0)
use
if (buttonState == HIGH && lastButtonState==LOW)

.

I implemented the pullup resistor with an actual resistor, but I know how the INPUT_PULLUP works.

Thanks for your reply, but do you have any idea on how to declare the timeCheck function i proposed I mentioned?

6

This should work:

  . . . 

  lastButtonState = buttonState;

  timeCheck();

} //end loop()

void timeCheck()
{
  if (millis() - t1 >= timeLimit)
  {
    digitalWrite(L1, 0);
  }
  if (millis() - t2 >= timeLimit)
  {
    digitalWrite(L2, 0);
  }
  if (millis() - t3 >= timeLimit)
  {
    digitalWrite(L3, 0);
  }
}
7

Note:
You have set up a potential problem with the way you are using this.
if (millis() - t1 >= timeLimit)
{
digitalWrite(L1, 0);
}

The code will constantly turn off the LED when >= is met.
This might be hard find, in a much larger program, if you ever turn on L1 somewhere else.
Also, at every ~72 days >= will not be true for 2.5 seconds.

It is best to include a disable flag to preempt the above.
if (L1Flag == true && millis() - t1 >= timeLimit)
{
digitalWrite(L1, 0);
L1Flag = false;
}

And in:
case 1:
digitalWrite(L1,1);
t1=millis();
L1Flag = true;
break;

8

LarryD:
This should work:

  . . .

lastButtonState = buttonState;

timeCheck();

} //end loop()

void timeCheck()
{
  if (millis() - t1 >= timeLimit)
  {
    digitalWrite(L1, 0);
  }
  if (millis() - t2 >= timeLimit)
  {
    digitalWrite(L2, 0);
  }
  if (millis() - t3 >= timeLimit)
  {
    digitalWrite(L3, 0);
  }
}

Thanks for the input. Your approach worked. Thanks!