diff --git a/a8/xtimer.cc b/a8/xtimer.cc
index 824cc82..547fce3 100644
--- a/a8/xtimer.cc
+++ b/a8/xtimer.cc
@@ -119,7 +119,6 @@ namespace a8
     {
         base_ = new xtvec_base();
         base_->running_timer = nullptr;
-        base_->timer_tick = get_tick_count_func_(context_);
         INIT_LIST_HEAD(&base_->free_timer);
         base_->free_timer_num = 0;
         for (int j = 0; j < TVN_SIZE; j++) {
@@ -143,9 +142,12 @@ namespace a8
     void XTimer::Init(XGetTickCountFunc func, void* context, int gc_time, int cache_timer_num)
     {
         get_tick_count_func_ = func;
-        context_ = context_;
+        context_ = context;
         gc_time_ = gc_time;
         cache_timer_num_ = cache_timer_num;
+        #if 1
+        base_->timer_tick = get_tick_count_func_(context_);
+        #endif
         AddRepeatTimer(gc_time_,
                        a8::XParams().SetSender(this),
                        &XTimer::GC_XTimerFunc);
@@ -197,6 +199,14 @@ namespace a8
         return timer;
     }
 
+    xtimer_list* XTimer::AddRepeatTimerAndAttach(int expire_time, a8::XParams param, a8::XTimerFunc timer_func,
+                                                 list_head* attach_list)
+    {
+        xtimer_list* timer = AddRepeatTimer(expire_time, param, timer_func);
+        list_add_tail(&timer->attach_entry, attach_list);
+        return timer;
+    }
+
     void XTimer::ModifyTimer(xtimer_list* timer, int expire_time)
     {
         DetachTimer(timer);
@@ -218,6 +228,9 @@ namespace a8
 
     void XTimer::DeleteTimer(xtimer_list* timer)
     {
+        if (base_->running_timer == timer) {
+            base_->running_timer = nullptr;
+        }
         if (timer->timer_after_func) {
             timer->timer_after_func(timer->param);
         }
@@ -264,25 +277,27 @@ namespace a8
                 if (timer->timer_after_func) {
                     timer->timer_after_func(timer->param);
                 }
-                switch (timer->timer_type) {
-                case 1:
-                case 2: //循环类定时 fixed timer也是循环定时器
-                    {
-                        if (timer->timer_type == 2) {
-                            timer->fixed_timer_execute_times++;
+                if (base_->running_timer) {
+                    switch (timer->timer_type) {
+                    case 1:
+                    case 2: //循环类定时 fixed timer也是循环定时器
+                        {
+                            if (timer->timer_type == 2) {
+                                timer->fixed_timer_execute_times++;
+                            }
+                            ModifyTimer(timer, timer->expire_time);
                         }
-                        ModifyTimer(timer, timer->expire_time);
-                    }
-                    break;
-                default: //deadline timer
-                    {
-                        DetachTimer(timer);
-                        if (!list_empty(&timer->attach_entry)) {
-                            list_del_init(&timer->attach_entry);
+                        break;
+                    default: //deadline timer
+                        {
+                            DetachTimer(timer);
+                            if (!list_empty(&timer->attach_entry)) {
+                                list_del_init(&timer->attach_entry);
+                            }
+                            AddToFreeList(timer);
                         }
-                        AddToFreeList(timer);
+                        break;
                     }
-                    break;
                 }
             }
         }
diff --git a/a8/xtimer.h b/a8/xtimer.h
index f398f74..76d08c8 100644
--- a/a8/xtimer.h
+++ b/a8/xtimer.h
@@ -15,11 +15,10 @@ namespace a8
 
     class XTimer
     {
-    private:
+    public:
         XTimer();
         ~XTimer();
 
-    public:
         void Init(XGetTickCountFunc func, void* context, int gc_time, int cache_timer_num);
 
         void Update();
@@ -33,6 +32,8 @@ namespace a8
                                                a8::XTimerAfterFunc timer_after_func = nullptr);
         //添加重复执行定时器(周期性定时器)
         xtimer_list* AddRepeatTimer(int expire_time, a8::XParams param, a8::XTimerFunc timer_func);
+        xtimer_list* AddRepeatTimerAndAttach(int expire_time, a8::XParams param, a8::XTimerFunc timer_func,
+                                             list_head* attach_list);
         //修改定时器参数
         void  ModifyTimer(xtimer_list* timer, int expire_time);
         //删除定时器