I declare "p" in one function, and use it in another. How can I decl

PWM - GPIO::PWM p(output_pin, 50); about jetsongpio HOT 4 CLOSED

pjueon commented on July 28, 2024

PWM - GPIO::PWM p(output_pin, 50);

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Comments (4)

pjueon commented on July 28, 2024

I'm not sure if I understand your question correctly, but maybe something like this?

// factory function for PWM
GPIO::PWM CreatePWMObject(int output_pin)
{
        // Pin Setup.	
        // Board pin-numbering scheme	
        GPIO::setmode(GPIO::BOARD);
	// set pin as an output pin with optional initial state of HIGH	
        GPIO::setup(output_pin, GPIO::OUT, GPIO::HIGH);	

        GPIO::PWM p(output_pin, 50);

        return p;
}


// declare "p" as a global variable
static GPIO::PWM p = CreatePWMObject(output_pin);

int main()
{
    // your code...
}

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TungTT1311 commented on July 28, 2024

Oke thanks you

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TungTT1311 commented on July 28, 2024

/home/jetson/Desktop/person_detection/pedestrian_detection/test.cpp:246:10: error: use of deleted function ‘GPIO::PWM::PWM(const GPIO::PWM&)’
return p;
I used it but error.

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pjueon commented on July 28, 2024

Oops, my bad. I forgot that PWM objects cannot be copied.
I added move constructor and move assign operator to PWM class just now. Now you can move the PWM object.

So,

Update your local repository:
(Assume you're in the JetsonGPIO directory)
git pull
Rebuild & reinstall the library:

cd build
make all
sudo make install

Try the above example code again.

Or you can also just use p as reference to the static instance.
Something like this:

// get the reference to static instance of PWM object
GPIO::PWM& GetPWMObject(int output_pin)
{
        // Pin Setup.	
        // Board pin-numbering scheme	
        GPIO::setmode(GPIO::BOARD);
	// set pin as an output pin with optional initial state of HIGH	
        GPIO::setup(output_pin, GPIO::OUT, GPIO::HIGH);	

        // note that p will be initialized only once even if you call GetPWMObject function multiple times. 
        static GPIO::PWM p(output_pin, 50);
        return p;
}


// declare "p" as a global reference to the static instance of PWM object. 
static GPIO::PWM& p = GetPWMObject(output_pin);

int main()
{
    // your code...
}