Random zero appears in display!

Projects Programming
5

  • 5 minutes + 27 seconds is 327000 milliseconds

  • You divide this number by interval which is (1000/100) = 10 (not 100 as the comment says) so the result is close to the max of a signed 16 bits int

  • You store the result in elapsedFrame which is a signed 16 bits int.

So a few milliseconds later, elapsedFrame will be negative and the rest of your code will break

One solution is to use a type that can hold a much bigger value, like uint32_t (unsigned long)

Here is an example that should demonstrate the problem

int frameRate = 100; 
long interval = (1000/frameRate);
long elapsedTime;
int elapsedFrames;

void setup()
{
  Serial.begin(57600);
}

void loop()
{
  elapsedTime = micros();
  elapsedFrames = (elapsedTime / interval); // divide by 10, not 100
  Serial.print( "elapsedTime = " );
  Serial.print( elapsedTime );
  Serial.print( " elapsedFrames = " );
  Serial.println( elapsedFrames );
}

Then change int elapsedFrames; to uint32_t elapsedFrames; and see the difference