text: #include "mbed.h"
  #include "cmsis_os.h"
  
  osSemaphoreId two_slots;
  osSemaphoreDef(two_slots);
  
  void test_thread(void const *name) {
      while (true) {
          osSemaphoreWait(two_slots, osWaitForever);
          printf("%s\n\r", (const char*)name);
          osDelay(1000);
          osSemaphoreRelease(two_slots);
      }
  }
  
  void t2(void const *argument) {test_thread("Th 2");}
  osThreadDef(t2, osPriorityNormal, DEFAULT_STACK_SIZE);
  
  void t3(void const *argument) {test_thread("Th 3");}
  osThreadDef(t3, osPriorityNormal, DEFAULT_STACK_SIZE);
  
  int main (void) {
      two_slots = osSemaphoreCreate(osSemaphore(two_slots), 2);
  
      osThreadCreate(osThread(t2), NULL);
      osThreadCreate(osThread(t3), NULL);
  
      test_thread((void *)"Th 1");
  }
  