File content as of revision 7:ff2e3fbefea7:

#include "mbed.h"
#include "rtos.h"

DigitalOut led1(LED1);
DigitalOut led2(LED2);
 
Mutex led_mutex; 

void delay(void){
for(int i=0;i<65000;i++){
    for(int j=0;j<100;j++)
    {
        }
 }
}
 
void test_thread1(void const *args) {
    while (true) {
        led_mutex.lock();
        printf("thd1 toogling\n");
        led1 = !led1;
        delay();
        led_mutex.unlock();
        Thread::wait(1000);
    }
}

void test_thread2(void const *args) {
    while (true) {
        led_mutex.lock();
        printf("thd2 toogling\n");
        led1 = !led1;
        delay();
        led_mutex.unlock();
        Thread::wait(1000);
    }
}
void test_thread(void const *args) {
    while (true) {
        led_mutex.lock();
        printf("main toogling\n");
        led1 = !led1;
        delay();
        led_mutex.unlock();
        Thread::wait(1000);
    }
}
 
int main() {
    Thread t2(test_thread1, (void *)"Th 1");
    Thread t3(test_thread2, (void *)"Th 2");
    
    test_thread((void *)"main");
}