WPF两轮车雷达上位机开发

前言

开发两轮车雷达，调试过程中需要一个上位机程序，接收雷达传输的信息，显示在屏幕上，指示哪边来车。本篇博文将记录开发上位机的过程和遇到的问题

开发过程

窗体设置

1. 添加串口和波特率设置
2. 添加波特率和COM口选项

   List<int> listOfBaudrate = new List<int>
   {
         2400, 4800, 9600, 19200, 38400, 57600, 115200
   };
   List<string> listOfPort = new List<string>(System.IO.Ports.SerialPort.GetPortNames());
   ComboBox_Port.ItemsSource = listOfPort;
   ComboBox_Port.SelectedIndex = 0;
   ComboBox_Baudrate.ItemsSource = listOfBaudrate;
   ComboBox_Baudrate.SelectedIndex = 6;

3. 添加警示文字
4. 把警示文字设置成不可见

后台程序

1. 串口初始化

   private void SerialPortInit()
   {
      try
      {
         serialPort = new SerialPort();
         serialPort.PortName = ComboBox_Port.SelectedItem.ToString();
         serialPort.BaudRate = (int)ComboBox_Baudrate.SelectedItem;
         serialPort.DataBits = 8;
         serialPort.StopBits = StopBits.One;
         serialPort.Parity = Parity.None;
      }
      catch(Exception ex) 
      {
         MessageBox.Show(ex.Message);
      }
   }

2. 串口开启与关闭函数

   private void SerialPortOpen()
   {
       SerialPortInit();
       serialPort.Open();
       serialPort.DataReceived += SerialPort_DataReceived;
   }
   
   private void SerialPortClose()
   {
       serialPort.Close();
       serialPort.Dispose();
       serialPort = null;
   }

3. 串口接收回调函数
   由于接收回调函数是在另外一个线程调用的，不能直接修改GUI，需要用Dispathcer.Invoke()函数调用GUI线程。
   此外，await可以进行一个异步等待，不影响GUI线程处理，本线程等待。借此实现一段时间后自动熄灭警示的功能。

   private async void SerialPort_DataReceived(object sender, SerialDataReceivedEventArgs e)
   {
       int len = serialPort.BytesToRead;
       byte[] data = new byte[len];
       serialPort.Read(data, 0, len);
       string str = Encoding.ASCII.GetString(data);
       try
       {
           if (str == "Left")
           {
               Dispatcher.Invoke(() =>
               {
                   this.left.Visibility = Visibility.Visible;
               });
               await Task.Delay(500);
               Dispatcher.Invoke(() =>
               {
                   this.left.Visibility = Visibility.Collapsed;
               });
           }
           else if (str == "Right")
           {
               Dispatcher.Invoke(() =>
               {
                   this.right.Visibility = Visibility.Visible;
               });
               await Task.Delay(500);
               Dispatcher.Invoke(() =>
               {
                   this.right.Visibility = Visibility.Collapsed;
               });
           }
           else
           {
               error.Visibility = Visibility.Visible;
               await Task.Delay(500);
               error.Visibility = Visibility.Collapsed;
           }
       }
       catch (Exception ex)
       {
           MessageBox.Show(ex.Message);
       }
   }