diff --git a/cpp/a.out b/cpp/a.out
index c42e6c4..1ec3e0d 100755
Binary files a/cpp/a.out and b/cpp/a.out differ
diff --git a/cpp/main.cpp b/cpp/main.cpp
index 1bf0f9d..3cd7fda 100644
--- a/cpp/main.cpp
+++ b/cpp/main.cpp
@@ -15,25 +15,66 @@
 
 using namespace iflytop;
 class Uart g_uart;
+int        g_rec_len;
+
+void *thread_uart_send(void *arg) {
+  while (1) {
+    if (g_rec_len > 0) {
+      g_uart.send((char *)arg, g_rec_len);
+      g_rec_len = 0;
+    }
+    usleep(1000);
+  }
+}
+
+void *thread_uart_receive(void *arg) {
+  while (1) {
+    if (g_rec_len == 0) {
+      g_rec_len = g_uart.receive((char *)arg, 128);
+    }
+    usleep(1000);
+  }
+}
 
 int main(int argc, char *argv[]) {
-  int  rec_len;
-  char buffer[128];
+  char share_buffer[128];
+
+  pthread_t       pid1, pid2;
+  pthread_attr_t *pthread_arr1, *pthread_arr2;
+  pthread_arr1 = NULL;
+  pthread_arr2 = NULL;
 
   if (argc != 3) {
     cout << "input error,please input ttyS and baudrate" << endl;
-    return 0;
+    return -1;
+  }
+
+  if (g_uart.open(argv[1], argv[2]) < 0) {
+    cout << "open uart error" << endl;
+    return -2;
+  } else {
+    cout << "open uart success" << endl;
   }
 
-  g_uart.open(argv[1], argv[2]);
+  if (pthread_create(&pid1, pthread_arr1, thread_uart_send, (void *)&share_buffer) != 0) {
+    cout << "create uart send thread error" << endl;
+    return -3;
+  } else {
+    cout << "create uart send thread success" << endl;
+  }
+  
+  if (pthread_create(&pid2, pthread_arr2, thread_uart_receive, (void *)&share_buffer) != 0) {
+    cout << "create uart receive thread error" << endl;
+    return -4;
+  } else {
+    cout << "create uart receive thread success" << endl;
+  }
 
   while (1) {
-    rec_len = g_uart.receive(buffer, sizeof(buffer));
-    if (rec_len > 0) {
-      g_uart.send(buffer, rec_len);
-      memset(buffer, 0, sizeof(buffer));
-    }
-    usleep(1000);
+    usleep(100000);
   }
+
+  pthread_join(pid1, NULL);
+  pthread_join(pid2, NULL);
   return 0;
 }
diff --git a/cpp/uart.cpp b/cpp/uart.cpp
index 9cb3c92..0bc3305 100644
--- a/cpp/uart.cpp
+++ b/cpp/uart.cpp
@@ -35,7 +35,7 @@ int Uart::open(string path, string ratestr) {
   }
 
   if (s_baudratemap.find(ratestr) == s_baudratemap.end()) {
-    return -1;
+    return -2;
   }
   m_rate = ratestr;