ctrl.cpp

#include "application.h"
#include "ctrl.h"

Ctrl::Ctrl() 
{
    init();
}
Ctrl::~Ctrl(){
    
}


void Ctrl::init(void){
    pinMode(D7, OUTPUT);
    digitalWrite(D7, HIGH);
}

ctrl.h

class Ctrl {
    public:
    
        Ctrl();
        ~Ctrl();
    
        void init(void);
};

startup_example.ino

// This #include statement was automatically added by the Particle IDE.
#include "ctrl.h"

Ctrl ctrl = Ctrl();

void setup() {
    digitalWrite(D7, LOW);
}

void loop() {

}