16, 2 LCD trying to blink colon

Projects Programming
1

Can anyone please tell me why this does not work?

void BlinkColon()
{
  static unsigned long ColonBlink;
  while (millis() > ColonBlink + 1000)
  {
    lcd.setCursor(13, 0);
    lcd.print(":");
    ColonBlink = millis();
  }
  while (millis() > ColonBlink + 1000)
  {
    lcd.setCursor(13, 0);
    lcd.print(" ");
    ColonBlink = millis();
  }
}

What i am trying to is to get time colon separator to blink without delay on my clock

2

Because you keep on updating ColonBlink in the while loop. Chances that millis() is greater than ColonBlink + 1000 are very very slim because ColonBlink is nearly the same as millis() when you test at the beginning of the while.

3

Tried this still does not work

void BlinkColon()
{
  unsigned long ColonBlink = millis();
  const long ColonDelay = 1000;
  while (millis() - ColonBlink >= ColonDelay)
  {
    lcd.setCursor(13, 0);
    lcd.print(":");
    //ColonBlink = millis();
  }
  while (millis() - ColonBlink >= ColonDelay)
  {
    lcd.setCursor(13, 0);
    lcd.print(" ");
    
  }
}
4

something like this:

void setup() {
  // put your setup code here, to run once:

}

void loop() 
{
  BlinkColon();
}

void BlinkColon()
{
  static unsigned long ColonBlink = 0;
  static bool blinkState = false;
  if (millis() - ColonBlink >= 1000UL)
  {
    blinkState = -blinkState;
    lcd.setCursor(13, 0);
    lcd.print(blinkState ? ":" : " ");
    ColonBlink = millis();
  }
}
5

Between to the two while loops you need to 'reset' ColonBlink to the new time

while(...)
{
}
ColonBlink = millis();
while(...)
{
}

The way you have coded this does not have any benefits over a simple delay. If it's the intention to prevent blocking of the main loop where you call BlinkColon, you're not quite on track yet.

6

Try this untested non blocking version

void BlinkColon()
{
  static unsigned long ColonBlink = millis();
  static colonState = true;
  static char colonChar = ':';
  const long ColonDelay = 1000;
  if (millis() - ColonBlink >= ColonDelay)
  {
    if (colonChar == ':')
    {
      colonChar == ' ';
    }
    else
    {
      colonChar == ':';
    }
    lcd.setCursor(13, 0);
    lcd.print(colonChar);
    ColonBlink = millis();
  }
}
7

Thanks I will try all suggestions and update

8

UKHeliBob:
Try this untested non blocking version

  const long ColonDelay = 1000;

if (millis() - ColonBlink >= ColonDelay)
 {
   if (colonChar == ':')
   {
     colonChar == ' ';
   }
   else
   {
     colonChar == ':';
   }

but fix it a little first

9

I've been trying for ten minutes to blink my...oh...never mind.

10

Do you need this

static colonState = true;

I cant see where it being used

11

but fix it a little first

Pooh !

Corrected version

void BlinkColon()
{
  static unsigned long ColonBlink = millis();
  static char colonChar = ':';
  const long ColonDelay = 1000;
  if (millis() - ColonBlink >= ColonDelay)
  {
    if (colonChar == ':')
    {
      colonChar = ' ';
    }
    else
    {
      colonChar = ':';
    }
    lcd.setCursor(13, 0);
    lcd.print(colonChar);
    ColonBlink = millis();
  }
}
12

Thanks a lot