FunctionalInterrupt.ino

#include <Arduino.h>
#include <FunctionalInterrupt.h>

#define BUTTON1 16
#define BUTTON2 17

class Button
{
public:
	Button(uint8_t reqPin) : PIN(reqPin){
		pinMode(PIN, INPUT_PULLUP);
		attachInterrupt(PIN, std::bind(&Button::isr,this), FALLING);
	};
	~Button() {
		detachInterrupt(PIN);
	}

	void IRAM_ATTR isr() {
		numberKeyPresses += 1;
		pressed = true;
	}

	void checkPressed() {
		if (pressed) {
			Serial.printf("Button on pin %u has been pressed %u times\n", PIN, numberKeyPresses);
			pressed = false;
		}
	}

private:
	const uint8_t PIN;
    volatile uint32_t numberKeyPresses;
    volatile bool pressed;
};

Button button1(BUTTON1);
Button button2(BUTTON2);


void setup() {
    Serial.begin(115200);
}

void loop() {
	button1.checkPressed();
	button2.checkPressed();
}