Comments on: Arduino Millis() Rollover Handling http://www.faludi.com/2007/12/18/arduino-millis-rollover-handling/ Thu, 04 Dec 2008 21:19:56 +0000 http://wordpress.org/?v=2.6.3 By: faludi http://www.faludi.com/2007/12/18/arduino-millis-rollover-handling/#comment-548 faludi Mon, 24 Nov 2008 02:27:23 +0000 http://blog.faludi.com/2007/12/18/arduino-millis-rollover-handling/#comment-548 Glad you asked because it's worth noting that the millis() function was greatly improved in Arduino 0012: * Improved millis(): it now overflows after 49 days instead of 9 hours, but now uses slightly more processing power. I'm assuming this means that it now fills the full unsigned long variable. So in your case you should just be able to do the math. The rollover will cause your subtraction to overflow an the result would be correct. Glad you asked because it’s worth noting that the millis() function was greatly improved in Arduino 0012:

* Improved millis(): it now overflows after 49 days instead of 9 hours, but
now uses slightly more processing power.

I’m assuming this means that it now fills the full unsigned long variable. So in your case you should just be able to do the math. The rollover will cause your subtraction to overflow an the result would be correct.

]]> By: John http://www.faludi.com/2007/12/18/arduino-millis-rollover-handling/#comment-547 John Mon, 24 Nov 2008 01:59:41 +0000 http://blog.faludi.com/2007/12/18/arduino-millis-rollover-handling/#comment-547 I'm having a little difficulty understanding how I would use your rollover function in a scenario where I tick a clock if 1000 ms has elapsed, like: if( millis() - previousMillis > 1000 ) { previousMillis = millis(); // One second has elapsed, tick the clock. } It seems like this will "hiccup" during a rollover. I’m having a little difficulty understanding how I would use your rollover function in a scenario where I tick a clock if 1000 ms has elapsed, like:

if( millis() - previousMillis > 1000 ) {
previousMillis = millis();
// One second has elapsed, tick the clock.
}

It seems like this will “hiccup” during a rollover.

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