How to use attachInterrupt in class

Using Arduino Programming Questions
1

Hi guys,

I am creating the class MyOptocoupler supposed to manage the optocoupler on my robot. I have created a methode begin() for the pinMode declaration and the attacheInterrupt function, but I have got an error:

C:\Users\USER\Documents\Arduino\libraries\MyOptocoupler\MyOptocoupler.cpp: In member function 'void MyOptocoupler::begin(int)':
C:\Users\USER\Documents\Arduino\libraries\MyOptocoupler\MyOptocoupler.cpp:29:31: error: cannot convert 'void (MyOptocoupler::*)()' to 'void (*)()' for argument '2' to 'void attachInterrupt(uint8_t, void (*)(), int)'
   attachInterrupt(0, p, CHANGE);
                               ^
Erreur lors de la compilation.

So do you know how to convert void (MyOptocoupler::)() to void ()() ?

I give you my code :

MyOptocoupler.h

#ifndef MyOptocoupler_h
#define MyOptocoupler_h

#if defined(__AVR__)
	#include "Arduino.h"
#elif defined(__PIC32MX__)
	#include "WProgram.h"
#elif defined(__arm__)
	#include "Arduino.h"
#endif

class MyOptocoupler
{
	public:
		MyOptocoupler(int pin);				
		void begin();						
		void begin(int goalOfCount);
		void changement();					
		bool isOutOfCount();	
		


	private:
		int _pin;
		int _goalOfCount;
		volatile int _counter;

};

#endif

My Optocoupler.cpp:

#include "MyOptocoupler.h"

	MyOptocoupler::MyOptocoupler(int pin): _pin(pin), _counter(0)
	{
	
	}
	
	void MyOptocoupler::begin()
	{
                //Does not metter it will be quite the same as begin(int goalOfCount)

		//_goalOfCount = 0;
		//pinMode(_pin, INPUT);
		//attachInterrupt(digitalPinToInterrupt(_pin), changement, CHANGE);
	}
	
	void MyOptocoupler::begin(int goalOfCount)
	{
		_goalOfCount = goalOfCount;
		pinMode(_pin, INPUT);
		void (MyOptocoupler::*p)();
		p = &MyOptocoupler::changement;
		attachInterrupt(0, p, CHANGE);
	}
	
	void MyOptocoupler::changement()
	{
		_counter++;
	}
	
	bool MyOptocoupler::isOutOfCount()
	{
		return _counter >= _goalOfCount;
	}

Thank you so much for your help.

Frank

2

The only way you can get a pointer to a class member function is if that function is defined static. This topic is beat to death on a regular basis in this forum. A search will turn up numerous threads that explain the few options you have.

Regards,
Ray L.

3

I am creating the class MyOptocoupler supposed to manage the optocoupler on my robot.

Creating a class to deal with ONE instance of a piece of hardware is rarely useful. Why do you need a class?

4

Thank you for your answers ! The code I shared with you yesterday was an attempt but the first code I wrote was this:

void MyOptocoupler::begin(int goalOfCount)
	{
		_goalOfCount = goalOfCount;
		pinMode(_pin, INPUT);
		attachInterrupt(0, changement, CHANGE);
	}

And I don't uderstand why is it impossible. The error is:

C:\Users\USER\Documents\Arduino\libraries\MyOptocoupler\MyOptocoupler.cpp: In member function 'void MyOptocoupler::begin(int)':
C:\Users\USER\Documents\Arduino\libraries\MyOptocoupler\MyOptocoupler.cpp:29:40: error: cannot convert 'MyOptocoupler::changement' from type 'void (MyOptocoupler::)()' to type 'void (*)()'
   attachInterrupt(0, changement, CHANGE);
                                        ^
Erreur lors de la compilation.

And if I write this:

attachInterrupt(0, this->changement, CHANGE);

Here is the error:

C:\Users\USER\Documents\Arduino\libraries\MyOptocoupler\MyOptocoupler.cpp: In member function 'void MyOptocoupler::begin(int)':
C:\Users\USER\Documents\Arduino\libraries\MyOptocoupler\MyOptocoupler.cpp:29:46: error: cannot convert 'MyOptocoupler::changement' from type 'void (MyOptocoupler::)()' to type 'void (*)()'
   attachInterrupt(0, this->changement, CHANGE);
                                              ^
Erreur lors de la compilation.

@PaulS :

I need a class because I think it is more friendly to use. Moreover some guys in my team of work do not really understand how to code....

Thank you again for your help.

5

Thank you for your answers !

You need to actually read them. Ray told you the answer in reply #1.

6

Here is an example I worked out with Ray's advice:

http://forum.arduino.cc/index.php?topic=362294.5;wap2