串口传输文件（YModem协议）

深碍√TFBOYSˉ_ 2022-05-28 00:10 411阅读 0赞

需求：通过串口线实现应用程序固件烧录到单片机的flash中  
开发语言：C\#  
串口设置：串口号，波特率：115200；

文件传输函数如下：

//烧录文件函数
            public bool YmodemUploadFile()
            {
                /* control signals */
                const byte STX = 2;  // Start of TeXt 
                const byte EOT = 4;  // End Of Transmission
                const byte ACK = 6;  // Positive ACknowledgement
                const byte C = 67;   // capital letter C
                /* sizes */
                const int dataSize = 1024;
                const int crcSize = 2;
                /* THE PACKET: 1029 bytes */
                /* header: 3 bytes */
                // STX        
                int invertedPacketNumber = 255;
                /* data: 1024 bytes */
                byte[] data = new byte[dataSize];
                /* footer: 2 bytes */
                byte[] CRC = new byte[crcSize];
                /* get the file */
                //string strfilepath = m_configData.ini_burningfilespath;
                FileStream fileStream = new FileStream(@path, FileMode.Open, FileAccess.Read);//读取bin文件的path           
                m_strMsglogString += ("\r\nreading buring files...\r\n");
                ShowExcuteProcessInfo();            
                DateTime dt = DateTime.Now;
                byte[] ack;
                ack = new byte[] { 0x31 };
                try
                {
                    serialPort1.Write(ack, 0, 1);
                }
                catch
                {
                    MessageBox.Show("Exception");
                }
                Thread.Sleep(300);            
                try
                {
                    ///* send the initial packet with filename and filesize */
                    m_strMsglogString += ("waiting for the serial response...\r\n");
                    ShowExcuteProcessInfo(); 
                    int AAA = serialPort1.ReadByte();
                    //pictureBoxResult.BackgroundImage = Properties.Resources.faillight;
                    if (serialPort1.ReadByte() != C)
                    {
                        MessageBox.Show("Can't begin the transfer.");
                        //Console.WriteLine("Can't begin the transfer.");
                        //pictureBoxResult.BackgroundImage = Properties.Resources.faillight;
                        ShowTestFailResult();
                        return false;
                    }
                    m_strMsglogString += ("send the initial packet with filename and filesize ...\r\n");
                    ShowExcuteProcessInfo(); 
                    sendYmodemInitialPacket(STX, packetNumber, invertedPacketNumber, data, dataSize, path, fileStream, CRC, crcSize);
                    if (serialPort1.ReadByte() != ACK)
                    {
                        MessageBox.Show("Can't send the initial packet.");
                        ShowTestFailResult();
                        return false;
                    }
    
                    if (serialPort1.ReadByte() != C)
                    {
                        MessageBox.Show("22Can't send the initial packet.");
                        ShowTestFailResult();
                        return false;
                    }
                    btn_download.Invoke
               (
                        //委托，托管无参数的任何方法
                   new MethodInvoker
                   (
                       delegate
                       {
                           btn_download.Text = "正在烧录";
                       }
                   )
                );
                    /* send packets with a cycle until we send the last byte */
                    m_strMsglogString += ("\r\nsending packets...\r\n");
                    ShowExcuteProcessInfo(); 
                    int fileReadCount;
                    do
                    {
                        /* if this is the last packet fill the remaining bytes with 0 */
                        fileReadCount = fileStream.Read(data, 0, dataSize);
    
                        if (fileReadCount == 0) break;
                        if (fileReadCount != dataSize)
                            for (int i = fileReadCount; i < dataSize; i++)
                                data[i] = 0;
                        /*calculate packetNumber */
                        packetNumber++;
                        //if (packetNumber > 255)
                        //    packetNumber -= 256;
                        ThreadFunction();
                        Console.WriteLine(packetNumber);
                        //Thread.Sleep(300);
                        /* calculate invertedPacketNumber */
                        invertedPacketNumber = 255 - packetNumber % 256;
    
                        /* calculate CRC */
                        Crc16Ccitt crc16Ccitt = new Crc16Ccitt(InitialCrcValue.Zeros);
                        CRC = crc16Ccitt.ComputeChecksumBytes(data);
    
                        /* send the packet */
                        sendYmodemPacket(STX, packetNumber, invertedPacketNumber, data, dataSize, CRC, crcSize);
    
                        int iii = serialPort1.ReadByte();
                        /* wait for ACK */
                        if (iii != (int)ACK)
                        {
                            MessageBox.Show("Couldn't send a packet.");
                            //Console.WriteLine("Couldn't send a packet.");
                            ShowTestFailResult();
                            return false;
                        }
                    } while (dataSize == fileReadCount);
    
                    /* send EOT (tell the downloader we are finished) */
                    serialPort1.Write(new byte[] { EOT }, 0, 1);
                    /* send closing packet */
                    packetNumber = 0;
                    invertedPacketNumber = 255;
                    data = new byte[dataSize];
                    CRC = new byte[crcSize];
                    m_strMsglogString += ("\r\nsend closing packet...\r\n");
                    ShowExcuteProcessInfo(); 
                    sendYmodemClosingPacket(STX, packetNumber, invertedPacketNumber, data, dataSize, CRC, crcSize);
                    /* get ACK (downloader acknowledge the EOT) */
                    if (serialPort1.ReadByte() != ACK)
                    {
                        Console.WriteLine("Can't complete the transfer.");
                        ShowTestFailResult();
                        return false;
                    }
                }
                catch (TimeoutException)
                {
                    throw new Exception("Eductor does not answering");
                }
                finally
                {
                    fileStream.Close();
                }
                packetNumber = fsLen;
                ThreadFunction();            
                Console.WriteLine("File transfer is succesful");
                TimeSpan span = DateTime.Now - dt;
                btn_download.Invoke
               (
                    //委托，托管无参数的任何方法
                   new MethodInvoker
                   (
                       delegate
                       {
                           btn_download.Text = "开始烧录";
                       }
                   )
                );          
                m_strMsglogString += ("\r\n烧录完成，耗时:" + span.ToString() + "\r\n");
                ShowExcuteProcessInfo(); 
                txb_section.Invoke
               (
                    //委托，托管无参数的任何方法
                   new MethodInvoker
                   (
                       delegate
                       {
                           txb_section.Text = "0";
                       }
                   )
                );
                Thread.Sleep(2000);            
                return true;
            }

文件传输函数包含了YModem协议文件传输的过程，根据YModem协议，发送数据之前和之后都需建立握手通信，

//YModem协议 初始化包
            private void sendYmodemInitialPacket(byte STX, int packetNumber, int invertedPacketNumber, byte[] data, int dataSize, string path, FileStream fileStream, byte[] CRC, int crcSize)
            {
                string fileName = System.IO.Path.GetFileName(path);
                string fileSize = fileStream.Length.ToString();
    
                /* add filename to data */
                int i;
                for (i = 0; i < fileName.Length && (fileName.ToCharArray()[i] != 0); i++)
                {
                    data[i] = (byte)fileName.ToCharArray()[i];
                }
                data[i] = 0;
    
                /* add filesize to data */
                int j;
                for (j = 0; j < fileSize.Length && (fileSize.ToCharArray()[j] != 0); j++)
                {
                    data[(i + 1) + j] = (byte)fileSize.ToCharArray()[j];
                }
                data[(i + 1) + j] = 0;
    
                /* fill the remaining data bytes with 0 */
                for (int k = ((i + 1) + j) + 1; k < dataSize; k++)
                {
                    data[k] = 0;
                }
    
                /* calculate CRC */
                Crc16Ccitt crc16Ccitt = new Crc16Ccitt(InitialCrcValue.Zeros);
                CRC = crc16Ccitt.ComputeChecksumBytes(data);
    
                /* send the packet */
                sendYmodemPacket(STX, packetNumber, invertedPacketNumber, data, dataSize, CRC, crcSize);
            }
           
            //YModem协议 尾包
            private void sendYmodemClosingPacket(byte STX, int packetNumber, int invertedPacketNumber, byte[] data, int dataSize, byte[] CRC, int crcSize)
            {
                /* calculate CRC */
                Crc16Ccitt crc16Ccitt = new Crc16Ccitt(InitialCrcValue.Zeros);
                CRC = crc16Ccitt.ComputeChecksumBytes(data);
    
                /* send the packet */
                sendYmodemPacket(STX, packetNumber, invertedPacketNumber, data, dataSize, CRC, crcSize);
            }

以上是YModem协议进行文件传输的大致过程。由于YModem协议每次传输1024字节的数据，整个烧录文件是预加载的，可以根据具体情况加上进度条信息。

实现源码可参考：https://download.csdn.net/download/shufac/10308977