diff --git a/app/a.exe b/app/a.exe
index 5b570f6..663c3e4 100644
Binary files a/app/a.exe and b/app/a.exe differ
diff --git a/app/main.c b/app/main.c
index 24505cd..d8693b3 100644
--- a/app/main.c
+++ b/app/main.c
@@ -9,6 +9,7 @@ PORT serial_port;
 int  serial_com_id;
 
 int main(int argc, char *argv[]) {
+  int i = 0;
   /* 参数判断 */
   if (argc != 2) {
     printf("please input com id\n");
@@ -27,7 +28,9 @@ int main(int argc, char *argv[]) {
   serial_port = serial_init(serial_com_id, 115200, 8, 1, 0);
 
   while (1) {
-    Serial_SendData(serial_port, "hello finny", 12);
+    steering_gear_set_position(serial_port, (i % 5));
+    i = i + 1;
+    printf("i:%d\n", i);
     Sleep(1000);
   }
 
diff --git a/app/steering_gear.c b/app/steering_gear.c
index e69de29..3af46e8 100644
--- a/app/steering_gear.c
+++ b/app/steering_gear.c
@@ -0,0 +1,34 @@
+#include "steering_gear.h"
+
+#include <stdio.h>
+
+void steering_gear_set_position(PORT serial_com, int switch_position_mode) {
+  char buf_position_0[]    = {0xff, 0xff, 0x01, 0x07, 0x03, 0x2a, 0x00, 0x00, 0x00, 0x00, 0xca};
+  char buf_position_1024[] = {0xff, 0xff, 0x01, 0x07, 0x03, 0x2a, 0x04, 0x00, 0x00, 0x00, 0xc6};
+  char buf_position_2048[] = {0xff, 0xff, 0x01, 0x07, 0x03, 0x2a, 0x08, 0x00, 0x00, 0x00, 0xc2};
+  char buf_position_3071[] = {0xff, 0xff, 0x01, 0x07, 0x03, 0x2a, 0x0b, 0xff, 0x00, 0x00, 0xc0};
+  char buf_position_4095[] = {0xff, 0xff, 0x01, 0x07, 0x03, 0x2a, 0x0f, 0xff, 0x00, 0x00, 0xbc};
+
+  printf("switch:%d\n", switch_position_mode);
+
+  switch (switch_position_mode) {
+    case 0:
+      Serial_SendData(serial_com, buf_position_0, sizeof(buf_position_0));
+      break;
+    case 1:
+      Serial_SendData(serial_com, buf_position_1024, sizeof(buf_position_1024));
+      break;
+    case 2:
+      Serial_SendData(serial_com, buf_position_2048, sizeof(buf_position_2048));
+      break;
+    case 3:
+      Serial_SendData(serial_com, buf_position_3071, sizeof(buf_position_3071));
+      break;
+    case 4:
+      Serial_SendData(serial_com, buf_position_4095, sizeof(buf_position_4095));
+      break;
+
+    default:
+      break;
+  }
+}
\ No newline at end of file
diff --git a/app/steering_gear.h b/app/steering_gear.h
index e69de29..255f333 100644
--- a/app/steering_gear.h
+++ b/app/steering_gear.h
@@ -0,0 +1,3 @@
+#include "serial.h"
+
+void steering_gear_set_position(PORT serial_com, int switch_position_mode);