TimerManager question

[vidojev]

Hello Bruno,

First I have to thank you for the library, it is helping me a lot to learn C++ basic with Arduino. I have a question regarding management of multiple timers, as I am unable to understand how does it work.

Here is a scenario:

We have 5 timers, like in your multi-timer example and I want to handle them independently (like start/stop/pause) in two groups, like first 3 and last 2. I know how this can be managed individually one by one, but as you have provided TimerManager class I would like to have that “nice” solution. I have tried numbers of options, but, as I am lacking knowledge of a professional, was unable to achieve anything but constant compile errors (mostly “Compilation error: expected primary-expression before '*' token” after trying with i.e. “TimerManager::instance().add(Timer *timer5);”).

Or, maybe approach is to add/remove timers to one single group and then to start/stop/pause them? Whatever it is, I have no idea how to setup a code to manage that…

Can you help with an advice/example for this scenario?

Thank you in advance,
Vidoje.

[brunocalou]

Hello,

The TimerManager class is a singleton, it's meant to be used to manage all timer instances at once. Unfortunately, there is no built-in way to create timer groups and manage them individually.

The TimerManager::add method is private. It can only be called from a TimerManager instance or from a Timer instance, since Timer is declared as a friend class on the TimerManager.h.

But it is indeed a valid use case. You can make your own TimerGroup class, for example, to achieve your goal. You can copy the TimerManager class, remove the instance method and change the constructor and the other methods to be public. Then you'll be able to create multiple TimerGroup instances and manage them individually.

Something like that:

timergroup.h

#ifndef TIMERGROUP_H
#define TIMERGROUP_H

#if defined(ARDUINO) && ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

#ifndef NULL
#define NULL 0
#endif

#include "timer.h"

class TimerGroup {
public:

  TimerGroup();
  TimerGroup(TimerGroup const &);
  void operator=(TimerGroup const &);

  /**
     Updates all timers
   */
  void update();

  /*
		Starts all timers
	*/
	void start();

	/*
		Stops and resets all timers
	*/
	void stop();

	/*
		Pauses all timers
	*/
	void pause();

	/*
		Resets elapsed time of all timers. If any timer was running, it will continue to do so
	*/
	void reset();

  /**
     Adds a timer to the TimerGroup
   */
  void add(Timer *timer);

  /**
     Removes a timer from the TimerGroup
     @return True if the timer was removed, false otherwise
   */
  bool remove(Timer *timer);

  class TimerNode {
    public:
      TimerNode(Timer *timer) {
        next = NULL;
        value = timer;
      }
      TimerNode *next;
      Timer *value;
  };

  TimerNode *first;
  TimerNode *last;
};
#endif //TIMERGROUP_H

timergroup.cpp

#include "timergroup.h"
#include "timer.h"

TimerGroup::TimerGroup() {
  last = NULL;
  first = NULL;
}

void TimerGroup::update() {
  TimerNode *current = first;
  while (current != NULL) {
    current->value->update();
    current = current->next;
  }
}

void TimerGroup::start() {
  TimerNode *current = first;
  while (current != NULL) {
    current->value->start();
    current = current->next;
  }
}

void TimerGroup::stop() {
  TimerNode *current = first;
  while (current != NULL) {
    current->value->stop();
    current = current->next;
  }
}

void TimerGroup::pause() {
  TimerNode *current = first;
  while (current != NULL) {
    current->value->pause();
    current = current->next;
  }
}

void TimerGroup::reset() {
  TimerNode *current = first;
  while (current != NULL) {
    current->value->reset();
    current = current->next;
  }
}

void TimerGroup::add(Timer *timer) {
  TimerNode* node = new TimerNode(timer);

  if (last == NULL) {
    last = node;
    first = node;
  } else {
    last->next = node;
    last = node;
  }
}

bool TimerGroup::remove(Timer *timer) {
  TimerNode *current = first;
  TimerNode *previous = NULL;

  while (current != NULL) {
    if (current->value == timer) {
      if (previous != NULL) {
        previous->next = current->next;
      }

      if (current == last) {
        last = previous;
      }

      if (current == first) {
        first = current->next;
      }

      delete current;
      return true;
    }

    previous = current;
    current = current->next;
  }

  return false;
}

Usage

// Create timers
Timer timer1;
Timer timer2;
Timer timer3;
Timer timer4;
Timer timer5;

// Create TimerGroup instances and manage them
TimerGroup group1;
group1.add(&timer1);
group1.add(&timer2);

TimerGroup group2;
group2.add(&timer3);
group2.add(&timer4);
group2.add(&timer5);

// Start just group 1
group1.start();

// Stop just group 2
group2.stop();

I haven't tested this code, but that's the general idea.