elapsedMillis and elapsedMicros library

Folks, for anyone interested, here is elapsedMillis and elapsedMicros (adapted by pfeerick from work done by Paul Stoffregen) simplifies timing loops a lot. This codes required NO adaptation for the Spark so I take no credit :smile:

Here it is with an simple LED blink example. Cheers!

// -------- elapsedMillis.h --------

/* Elapsed time types - for easy-to-use measurements of elapsed time
 * http://www.pjrc.com/teensy/
 * Copyright (c) 2011 PJRC.COM, LLC
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */


class elapsedMillis
{
private:
	unsigned long ms;
public:
	elapsedMillis(void) { ms = millis(); }
	elapsedMillis(unsigned long val) { ms = millis() - val; }
	elapsedMillis(const elapsedMillis &orig) { ms = orig.ms; }
	operator unsigned long () const { return millis() - ms; }
	elapsedMillis & operator = (const elapsedMillis &rhs) { ms = rhs.ms; return *this; }
	elapsedMillis & operator = (unsigned long val) { ms = millis() - val; return *this; }
	elapsedMillis & operator -= (unsigned long val)      { ms += val ; return *this; }
	elapsedMillis & operator += (unsigned long val)      { ms -= val ; return *this; }
	elapsedMillis operator - (int val) const           { elapsedMillis r(*this); r.ms += val; return r; }
	elapsedMillis operator - (unsigned int val) const  { elapsedMillis r(*this); r.ms += val; return r; }
	elapsedMillis operator - (long val) const          { elapsedMillis r(*this); r.ms += val; return r; }
	elapsedMillis operator - (unsigned long val) const { elapsedMillis r(*this); r.ms += val; return r; }
	elapsedMillis operator + (int val) const           { elapsedMillis r(*this); r.ms -= val; return r; }
	elapsedMillis operator + (unsigned int val) const  { elapsedMillis r(*this); r.ms -= val; return r; }
	elapsedMillis operator + (long val) const          { elapsedMillis r(*this); r.ms -= val; return r; }
	elapsedMillis operator + (unsigned long val) const { elapsedMillis r(*this); r.ms -= val; return r; }
};

class elapsedMicros
{
private:
	unsigned long us;
public:
	elapsedMicros(void) { us = micros(); }
	elapsedMicros(unsigned long val) { us = micros() - val; }
	elapsedMicros(const elapsedMicros &orig) { us = orig.us; }
	operator unsigned long () const { return micros() - us; }
	elapsedMicros & operator = (const elapsedMicros &rhs) { us = rhs.us; return *this; }
	elapsedMicros & operator = (unsigned long val) { us = micros() - val; return *this; }
	elapsedMicros & operator -= (unsigned long val)      { us += val ; return *this; }
	elapsedMicros & operator += (unsigned long val)      { us -= val ; return *this; }
	elapsedMicros operator - (int val) const           { elapsedMicros r(*this); r.us += val; return r; }
	elapsedMicros operator - (unsigned int val) const  { elapsedMicros r(*this); r.us += val; return r; }
	elapsedMicros operator - (long val) const          { elapsedMicros r(*this); r.us += val; return r; }
	elapsedMicros operator - (unsigned long val) const { elapsedMicros r(*this); r.us += val; return r; }
	elapsedMicros operator + (int val) const           { elapsedMicros r(*this); r.us -= val; return r; }
	elapsedMicros operator + (unsigned int val) const  { elapsedMicros r(*this); r.us -= val; return r; }
	elapsedMicros operator + (long val) const          { elapsedMicros r(*this); r.us -= val; return r; }
	elapsedMicros operator + (unsigned long val) const { elapsedMicros r(*this); r.us -= val; return r; }
};

// -------- end elapsedMillis.h --------

elapsedMillis timeElapsed; //declare global if you don't want it reset every time loop runs

// Pin 13 has an LED connected on most Arduino boards.
int led = D7;

// delay in milliseconds between blinks of the LED
unsigned int interval = 1000;

// state of the LED = LOW is off, HIGH is on
boolean ledState = LOW;

void setup() 
{                
  // initialize the digital pin as an output.
  pinMode(led, OUTPUT);     
}

void loop()
{
  if (timeElapsed > interval) 
  {				
      ledState = !ledState;         // toggle the state from HIGH to LOW to HIGH to LOW ... 
      digitalWrite(led, ledState);
      timeElapsed = 0;              // reset the counter to 0 so the counting starts over...
  }
4 Likes

Awesome, thanks @peekay123!

Aww, I wanted this to be way cooler than it looks to be! :slight_smile:

I think this would be better as:
elapsedMillis oneSecondElapsed(1000);

Instead of using the global
unsigned int interval = 1000;

And then the if:
if ( oneSecondElapsed ) { oneSecondElapsed.reset(); }

My “educator’s opinion”… I’m a Timing Guy… I love to think about how timing works, and abstracting away the super simple process of millis() - startTime > timeInterval, that is… making a whole class just to hide the millis() - startTime really makes me cringe. One reason is if you don’t do much timing stuff, you’ll probably never learn exactly what’s going on there because it’s abstracted away in a Class with lots of constructors and not that easy to see. The concept of elapsedTime > timeInteval is fine I guess but if you get into a jam timing wise it might not be so obvious why. There are lots of people that like to wrap functions inside functions inside functions inside more functions so this is probably sweet for them. You ultimately end up with:

#include <Skynet.h>

Skynet myapp();
void setup() {
  myapp.run();
}
void loop() {
 // haha, nope.avi
}
3 Likes

BDub, you have entirely too much time on your hands dude! :wink:

I left the library as-is due to legacy porting but your approach. I think your class wrapper is another great take on the code. POST IT!

Now do it in microseconds!

It’s up there already @timb

I updated the topic title and description to include elapsedMicros. :smile:

Bdub, thank you very much for expressing so succinctly and with such very good humour exactly your and my frustration with the timer solution offered. What I would like is a timer interrupt setup call (very similar to the other interrupt setup calls) where I specify which function to call every so many millis or micros. Pending that, and as I only need millis, I’ll just do my own millis() - startTime > timeInterval processing in loop() as you suggest.

You may want to include a link to your IntervalTimer Library thread in your first post in case someone who found this really wants to use hardware timers (such as myself). :wink:

wgbartley, you just did!