diff --git a/src/timer.rs b/src/timer.rs
index 067f097..6e5500d 100644
--- a/src/timer.rs
+++ b/src/timer.rs
@@ -1,9 +1,14 @@
+use std::rc::{Rc, Weak};
+use std::cell::RefCell;
+
 pub struct TimerList {
 
 }
 
 pub struct Timer {
-
+    free_timer_num: i32,
+    free_timer_list: Rc::<RefCell::<crate::ListHead<TimerList>>>,
+    running_timer: Weak::<RefCell::<TimerList>>,
 }
 
 impl Timer {