事件也是一种在线程间同步的方式。

RTT中，事件是一个32bit（4个字节）的变量，其中每一个位可以表示代表一种事件。接收事件的线程既可以在多个事件同时发生后（即多个bit位同时置1）触发，正如本例中线程1中第一条语句所演示的那样。也可以多个事件任意一个发生后（即多个bit位任意一个置位）就可以触发。主程序中创建三个线程，线程1接收事件标志。线程2和线程3则向发送事件标志。可以说，事件更为灵活。

这里，一共创建了三个线程，一个事件。一开始 thread1 等待事件 bit3 和 bit5 发生，并且是 and 方式。thread2 和 thread3 分别发送了bit3 和 bit5 ，thread1收到之后，等待1s 进入下一次等待事件的发生。第二次事件是 or 的方式，即 bit3 和 bit5 只要有一个方式，事件就算发生，这时 thread3 发出 bit5 事件，thread1 收到后停止调度。

程序：

#include 
    
     #include 
     
      void rt_init_thread_entry(void *parameter){}static struct rt_event event;static rt_uint8_t thread1_stack[1024];struct rt_thread thread1;static void thread1_entry(void *parameter){    rt_uint32_t e;        if (rt_event_recv(&event, ((1 << 3) | (1 << 5)),        RT_EVENT_FLAG_AND | RT_EVENT_FLAG_CLEAR,        RT_WAITING_FOREVER, &e) == RT_EOK)    {        rt_kprintf("thread1: AND recv event 0x%x\n", e);    }        rt_kprintf("thread1: delay 1s to prepare second event.\n");    rt_thread_delay(RT_TICK_PER_SECOND);        if (rt_event_recv(&event, ((1 << 3) | (1 << 5)),        RT_EVENT_FLAG_OR | RT_EVENT_FLAG_CLEAR,        RT_WAITING_FOREVER, &e) == RT_EOK)    {        rt_kprintf("thread1: OR recv event 0x%x\n", e);    }    rt_kprintf("thread1 leave.\n");    }static rt_uint8_t thread2_stack[1024];struct rt_thread thread2;static void thread2_entry(void *param){    rt_kprintf("thread2: send event1\n");    rt_event_send(&event, (1 << 3));    rt_kprintf("thread2 leave.\n");}static rt_uint8_t thread3_stack[1024];struct rt_thread thread3;static void thread3_entry(void *param){    rt_kprintf("thread3: send event2\n");    rt_event_send(&event, (1 << 5));    rt_thread_delay(20);    rt_kprintf("thread3: send event2\n");    rt_event_send(&event, (1 << 5));    rt_kprintf("thread3 leave.\n");}int rt_application_init(){    rt_thread_t init_thread;    rt_err_t result;        result = rt_event_init(&event, "event",        RT_IPC_FLAG_FIFO);    if (result != RT_EOK)    {        rt_kprintf("init event failed.\n");        return -1;    }        init_thread = rt_thread_create("init",        rt_init_thread_entry, RT_NULL,        2048, 7, 20);    if (init_thread != RT_NULL)        rt_thread_startup(init_thread);        rt_thread_init(&thread1,        "t1",        thread1_entry, RT_NULL,        &thread1_stack[0], sizeof(thread1_stack),        8, 50);    rt_thread_startup(&thread1);        rt_thread_init(&thread2,                   "thread2",                   thread2_entry,                   RT_NULL,                   &thread2_stack[0],                   sizeof(thread2_stack),9,50);    rt_thread_startup(&thread2);    rt_thread_init(&thread3,                   "thread3",                   thread3_entry,                   RT_NULL,                   &thread3_stack[0],                   sizeof(thread3_stack),10,50);    rt_thread_startup(&thread3);        return 0;}
     
    

结果：

thread2: send event1thread2 leave.thread3: send event2thread1: AND recv event 0x28thread1: delay 1s to prepare second eventthread3: send event2thread3 leave.thread1: OR recv event 0x20thread1 leave.