Why does this delay hang with certain values?

Projects Programming
1

Hello all, pretty much of a newb here, but trying to work things out. I have an issue with delay hanging when I try to use some values. Yes, I know there are other ways to blink an LED and to time it, such as millis, but I want to understand why this does not work.

The idea is to make the LED flash twice in a 60 second cycle. Flash 1 and Flash 3 happen 60 seconds apart, Flash 2 happens a variable time between 1 and 3. Flash 2 starts close to 1 and then walks closer to 3 for 60 cycles.

Yes, this is part of a larger effort, but this portion of the code will not run on its own for some reason with certain delays selected. For example, if I use 60 in the FOR loop (to get 60 seconds Flash 1 to Flash 3) it will give me the first 2 flashes and then hang, never flashing again after that. But it I use 30 (for a 30 second cycle) it runs fine.

Is there a maximum delay using the DELAY function, and if so have I exceeded it here? Or have I made some other bone headed mistake?

/*
Flash Cycle Investigation
*/


int led = 13;
int FlashSpeed = 4;
int PulseDelay = 0;


void setup()
{
  pinMode(led, OUTPUT);
}


void loop()
{
  FlashCycle();
}


void FlashCycle()
{
  FlashSpeed = 5;
  for (int i=1; i<60; i++)
  {
    Flash();
    delay (1000*i);
    Flash();
    PulseDelay = 60 - i;
    delay (1000*PulseDelay);
  }
}


void Flash()
{
  digitalWrite(led,HIGH);
  delay(25*FlashSpeed);
  digitalWrite(led,LOW);
  delay(25*FlashSpeed);
}

Any ideas? Thanks

T!

(edit) Sorry, did not specify, I am trying to run this on an UNO.

2

That cannot be the code that you are actually running as it does not compile.

digitaWrite in 2 places instead of digitalWrite and a semi-colon on the end of the for loop statement

3

Yes, sorry, typos. The computer with the code on it is not connected to the web, and this computer is locked down and cannot have the Arduino environment installed. I manually transcribed from one machine to the other and typoed.

I have corrected the two digtalWrites and the errant semi-colon. The rest appears to match what compiles.

T!

4

Your problem is with signed sixteen bit arithmetic in the call to your delay().

Edit: it isn't hanging, you're just not being patient enough.

5

You had a semicolon after the for loop.

This caused your loop to finish and then stop

6

AWOL:
Your problem is with signed sixteen bit arithmetic in the call to your delay().

Edit: it isn't hanging, you're just not being patient enough.

OK, I think I have it then, if I use more than 32 in my example, say 33, then the delay count becomes 33000, and 2's complement only up to 32767 can be accommodated?

T!

7

FirstToken:
, and 2's complement only up to 32767 can be accommodated?

Right. ALWAYS use unsigned long variables for millis(), mocros(), delay(), etc.

8

Excellent, thanks much for the answers.

T!