Arduino for STM32

UPDATE: The original piece of code works in PlatformIO. Looks like Arduino IDE is a problem here.

This will effectively make the class static, right? So there will be only one instance possible.

Yes, it's a pointer.

I tried to rewrite it the following way but the static method still isn't called

extern "C" {
void _onInterrupt(void)
{
digitalWrite(PC13, LOW);
//_thePSM->calculateSkip();
}
}

PSM::PSM(uint32_t sensePin, uint32_t mode)
{
_thePSM = this;

pinMode(sensePin, INPUT_PULLUP ...

Hello all,

Could anyone explain me what's wrong with this code in a C++ library:

.h file
class PSM
{
public:
PSM(uint32_t sensePin, uint32_t mode = RISING);

static void onInterrupt();

unsigned int cps();

private:
void calculateSkip();

volatile unsigned int _a;
};
.cpp file
static ...