File content as of revision 3:81621bb4f009:

#include "mbed.h"
#include "rtos.h"
 
//Interruptions
InterruptIn btn1(D7);
InterruptIn btn2(D6);
InterruptIn btn3(D5);
InterruptIn btn4(D4);



//Outs
DigitalOut buzzer(D2);
DigitalOut led(LED_BLUE);

//Buttons Threads
Thread threadb1, threadb2, threadb3, threadb4;

//Button function 
void button_pressed() {
  buzzer = !buzzer; // toggle the LED
  led = !led;
}

//Buttons threads
void button1_thread() {
    btn1.fall(&button_pressed); // whenever the button falls, execute button_pressed function
    while(1) {}
 }
 
 void button2_thread() {
    btn2.fall(&button_pressed); // whenever the button falls, execute button_pressed function
    while(1) {}
 }
 
 void button3_thread() {
    btn3.fall(&button_pressed); // whenever the button falls, execute button_pressed function
    while(1) {}
 }
 
 void button4_thread() {
    btn4.fall(&button_pressed); // whenever the button falls, execute button_pressed function
    while(1) {}
 }
 
int main(int, char**) {
  led = !led;
  threadb1.start(button1_thread);
  threadb2.start(button2_thread);
  threadb3.start(button3_thread);
  threadb4.start(button4_thread);
 
  while (1) {}
}