File content as of revision 1:d343cf676574:

#include "mbed.h"

DigitalOut myled1(LED1);
DigitalOut myled2(LED2);
DigitalOut myled3(LED3);
DigitalOut myled4(LED4);

InterruptIn mybutton(USER_BUTTON);

double tempo = 0.2;    //time to wait

void changetempo() {   
	if(tempo == 0.2)   // If leds have low frequency
		tempo = 0.1;   // Set the fast frequency
	else               // If les have fast frequency
		tempo = 0.2;   // Set the low frequency
}

int main() {
	myled1 = 0;            //LED1 is OFF
	myled2 = 0;            //LED2 is OFF
	myled3 = 0;            //LED3 is OFF
	myled4 = 0;            //LED4 is OFF

    mybutton.fall(&changetempo);  //Interrupt to change tempo

    while(1) {
        myled2 = 1;   // LED2 is ON
        wait(tempo);  // wait tempo
        myled2 = 0;   // LED2 is OFF
        myled1 = 1;   // LED1 is ON
        wait(tempo);  // wait tempo
        myled1 = 0;   // LED1 is OFF
        myled3 = 1;   // LED3 is ON
        wait(tempo);  // wait tempo
        myled3 = 0;   // LED3 is OFF
        myled4 = 1;   // LED4 is ON
        wait(tempo);  // wait tempo
        myled4 = 0;   // LED4 is OFF
    }
}