diff --git a/homework4/.eide/eide.json b/homework4/.eide/eide.json
index 5e01018..8c6e288 100644
--- a/homework4/.eide/eide.json
+++ b/homework4/.eide/eide.json
@@ -18,9 +18,7 @@
   },
   "targets": {
     "Debug": {
-      "excludeList": [
-        "src/test1.c"
-      ],
+      "excludeList": [],
       "toolchain": "Keil_C51",
       "compileConfig": {
         "options": "null"
diff --git a/homework4/src/homework4.h b/homework4/src/homework4.h
index 691c3b1..5b0803b 100644
--- a/homework4/src/homework4.h
+++ b/homework4/src/homework4.h
@@ -29,18 +29,18 @@ sbit BUS8DP = P2 ^ 7;
 void set_38_2LED()
 {
     // e.g. set Y3 to 1, others to 0:
-    ADDR0 = 0;
+    ADDR0 = 1;
     ADDR1 = 1;
-    ADDR2 = 1;
+    ADDR2 = 0;
     ADDR3 = 1;
     ENLED = 0;
 }
 void set_38_2SEG()
 {
     // e.g. set Y4 to 1, others to 0:
-    ADDR0 = 1;
+    ADDR0 = 0;
     ADDR1 = 0;
-    ADDR2 = 0;
+    ADDR2 = 1;
     ADDR3 = 1;
     ENLED = 0;
 }
\ No newline at end of file
diff --git a/homework4/src/test1.c b/homework4/src/test1.c
new file mode 100644
index 0000000..990264a
--- /dev/null
+++ b/homework4/src/test1.c
@@ -0,0 +1,30 @@
+// test1.c
+// 通过定时器实现以0.5Hz的频率闪烁一个小灯
+#include "homework4.h"
+
+unsigned char cnt = 0; // log timer T0 overflow counts
+
+void test1()
+{
+    set_38_2LED();
+    TMOD = 0x01; // timer T0 mode 1, 16-bit timer
+    TH0  = 0XB8;
+    TL0  = 0X00;
+    TR0  = 1; // timer T0 run
+    while (1) {
+        if (TF0 == 1) { // timer T0 overflow
+            TF0 = 0;    // clear timer T0 overflow flag
+            TH0 = 0xB8; // reload timer T0 value
+            TL0 = 0x00;
+            cnt++; // log timer T0 overflow counts
+            if (cnt >= 50) {
+                cnt   = 0;      // clear log timer T0 overflow counts
+                BUS1A = ~BUS1A; // toggle LED
+            }
+        }
+    }
+}
+void main()
+{
+    test1();
+}
\ No newline at end of file