File content as of revision 2:3d65cd8d7089:

#include "mbed.h"

#define RED_OFF    1
#define YELLOW_OFF 2
#define GREEN_OFF  4
#define ALL_OFF    7

//Function declarations
void Function1();
void Function2();
void Function3();
void Function4();

//I/O
DigitalOut onBoardLED(LED1);
DigitalOut redLED(D7);
DigitalOut yellowLED(D6);
DigitalOut greenLED(D5);

DigitalIn  onBoardSwitch(USER_BUTTON);
DigitalIn  SW1(D4);
DigitalIn  SW2(D3);

Thread t1;
Thread t2;
Thread t3;
Thread t4;

//Thread ID
osThreadId idMain;
osThreadId id1;
osThreadId id2;
osThreadId id3;
osThreadId id4;

void Function1()
{
    while (true) {
        redLED = !redLED;
        if (redLED == 0) {
            t2.signal_set(RED_OFF);
        }
        Thread::wait(1000);
    }
}

void Function2()
{
    while (true) {
        Thread::signal_wait(RED_OFF);
        yellowLED = !yellowLED;
        if (yellowLED == 0) {
            t3.signal_set(YELLOW_OFF);
        }
    }
}

//Green Flashing
void Function3()
{
    while (true) {
        Thread::signal_wait(YELLOW_OFF);
        greenLED = !greenLED;
        if (greenLED == 0) {
            t4.signal_set(GREEN_OFF);
        }       
    }
}

//This function waits for signals from all other threads
void Function4()
{
    while (true) {
        Thread::signal_wait(GREEN_OFF);
        //Signal main thread       
        osSignalSet(idMain, ALL_OFF);              
    }
}

//Main thread
int main() {
    redLED    = 0;
    yellowLED = 0;
    greenLED  = 0;
    
    //Main thread ID
    idMain = osThreadGetId();   //CMSIS RTOS call
    
    // run threads
    t4.start(Function4);
    t1.start(Function1);           
    t2.start(Function2);    
    t3.start(Function3);     

    
    //Thread ID
    id1 = t1.gettid();
    id2 = t2.gettid();
    id3 = t3.gettid();
    id4 = t4.gettid();
    
    while(1) {
        //Wait for the ALL_ON signal
        osSignalWait(ALL_OFF,osWaitForever);
        printf("ALL OFF\n");
    }
}