diff --git a/cpp/a.out b/cpp/a.out
index 52c5bcd..c42e6c4 100755
Binary files a/cpp/a.out and b/cpp/a.out differ
diff --git a/cpp/main.cpp b/cpp/main.cpp
index c332876..1bf0f9d 100644
--- a/cpp/main.cpp
+++ b/cpp/main.cpp
@@ -20,12 +20,18 @@ int main(int argc, char *argv[]) {
   int  rec_len;
   char buffer[128];
 
-  g_uart.open(argv[1]);
+  if (argc != 3) {
+    cout << "input error,please input ttyS and baudrate" << endl;
+    return 0;
+  }
+
+  g_uart.open(argv[1], argv[2]);
 
   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);
   }
diff --git a/cpp/uart.cpp b/cpp/uart.cpp
index d015ad3..9cb3c92 100644
--- a/cpp/uart.cpp
+++ b/cpp/uart.cpp
@@ -10,12 +10,22 @@
 using namespace iflytop;
 using namespace std;
 
+static map<string, uint32_t> s_baudratemap = {
+    {"0", B0},             {"50", B50},           {"75", B75},           {"110", B110},          //
+    {"134", B134},         {"150", B150},         {"200", B200},         {"300", B300},          //
+    {"600", B600},         {"1200", B1200},       {"1800", B1800},       {"2400", B2400},        //
+    {"4800", B4800},       {"9600", B9600},       {"19200", B19200},     {"38400", B38400},      //
+    {"57600", B57600},     {"115200", B115200},   {"230400", B230400},   {"460800", B460800},    //
+    {"500000", B500000},   {"576000", B576000},   {"921600", B921600},   {"1000000", B1000000},  //
+    {"1152000", B1152000}, {"1500000", B1500000}, {"2000000", B2000000}, {"2500000", B2500000},  //
+    {"3000000", B3000000}, {"3500000", B3500000}, {"4000000", B4000000},
+};
+
 Uart::Uart() {}
 Uart::~Uart() {}
 
-int Uart::open(string path) {
+int Uart::open(string path, string ratestr) {
   int rc;
-
   m_name = path;
 
   m_fd = ::open(path.c_str(), O_RDWR | O_NOCTTY);
@@ -24,22 +34,23 @@ int Uart::open(string path) {
     return -1;
   }
 
+  if (s_baudratemap.find(ratestr) == s_baudratemap.end()) {
+    return -1;
+  }
+  m_rate = ratestr;
+
   memset(&m_tty, 0, sizeof(m_tty));
 
   m_tty.c_cflag |= CLOCAL | CREAD;  // 激活本地连接与接受使能
-
-  m_tty.c_cflag &= ~CSIZE;  // 失能数据位屏蔽
-  m_tty.c_cflag |= CS8;     // 8位数据位
-
-  m_tty.c_cflag &= ~CSTOPB;  // 1位停止位
-
-  m_tty.c_cflag &= ~PARENB;  // 无校验位
-
+  m_tty.c_cflag &= ~CSIZE;          // 失能数据位屏蔽
+  m_tty.c_cflag |= CS8;             // 8位数据位
+  m_tty.c_cflag &= ~CSTOPB;         // 1位停止位
+  m_tty.c_cflag &= ~PARENB;         // 无校验位
   m_tty.c_cc[VTIME] = 0;
   m_tty.c_cc[VMIN]  = 0;
 
-  cfsetispeed(&m_tty, B115200);  // 设置输入波特率
-  cfsetospeed(&m_tty, B115200);  // 设置输出波特率
+  cfsetispeed(&m_tty, s_baudratemap[ratestr]);  // 设置输入波特率
+  cfsetospeed(&m_tty, s_baudratemap[ratestr]);  // 设置输出波特率
 
   tcflush(m_fd, TCIFLUSH);  // 刷清未处理的输入和/或输出
 
diff --git a/cpp/uart.hpp b/cpp/uart.hpp
index 5915501..4cf4168 100644
--- a/cpp/uart.hpp
+++ b/cpp/uart.hpp
@@ -19,14 +19,29 @@ class Uart {
  private:
   int            m_fd = 0;
   string         m_name;
-  int            m_rate = B115200;
+  string         m_rate;
   struct termios m_tty;
 
  public:
   Uart();
   ~Uart();
-
-  int open(string path);
+  /**
+   * @brief 打开串口
+   *
+   * @param path
+   * @param rate
+   *      "0"       "50"      "75"      "110"
+   *      "134"     "150"     "200"     "300"
+   *      "600"     "1200"    "1800"    "2400"
+   *      "4800"    "9600"    "19200"   "38400"
+   *      "57600"   "115200"  "230400"  "460800"
+   *      "500000"  "576000"  "921600"  "1000000"
+   *      "1152000" "1500000" "2000000" "2500000"
+   *      "3000000" "3500000" "4000000"
+   *
+   * @return int
+   */
+  int open(string path, string ratestr);
   int send(char *data, int size);
   int receive(char *data, int size_max);
   int close();