采用TCP协议实现PIC18F97J60 ethernet bootloader

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　　TCP/IP Stack

　　Microchip TCP/IP Stack是免费的，广泛应用于PIC单片机中。由于有远程更新程序的需求，我决定开发基于TCP协议的ethernet bootloader, 主要使用了Microchip TCP/IP Stack的TCP模块。最终我开发出来的ethernet bootloader 在PIC18F97J60上验证通过。整个实现上分两部分，一部分是单片机端的基于TCP协议的bootloader程序，我将其命名为PhnBoot_v2.0, 另外一部分是同样基于TCP协议与单片机互动的PC端通信程序，我将其命名为PhnLoader_v2.0。我还定义了PhnBoot_v2.0和PhnLoader_v2.0之间传输数据的通信协定。下面将细说我是如何实现的。

　　通信协定

　　单片机端PhnBoot_v2.0和PC端PhnLoader_v2.0之间的通信数据包采用以下协定

<STX><CMD><ADDRL><ADDRH><ADDRU><LEN><DATA>...<DATA><ETX>

　　定义如下:

STX - Start of packet indicator
ETX - End of packet indicator
LEN - The length of true data
DATA - General data 16 bytes, only first LEN of datas are true
CMD - Base command
ADDR - Address up to 24 bits  ( ADDRL , ADDRH , ADDRH)

　　具体有以下Base command:

RD-VER:  0x00 -- Read Version Information (最终版本删除了此命令)
RD_MEM： 0x01 -- Read Program Memory (最终版本删除了此命令)
ER_MEM: 0x03 -- Erase Program Memory
WR_MEM： 0x02 -- Write Program Memory
WR_CFG： 0x04 -- Write Configuration Registers

　　PhnLoader_v2.0 功能

　　定义好了通讯协定, 接着就按照协定去实现PhnLoader_v2.0。 PhnLoader_v2.0的具体功能包括选择IP地址，端口和协议类型, 目前只支持TCP协议, 创建TCP服务器，加载应用程序Hex文件，Parse 应用程序的Hex文件，一行一行解读Hex文件，一旦收到连接请求，建立TCP连接，一旦收到应用程序更新请求，立刻按照通讯协定采用TCP协议发送Hex记录到单片机，接收单片机发送回来的Response，发送完毕后断开TCP连接，发送期间出现问题就立马结束发送。

　　PhnLoader_v2.0 主要代码段

　　PhnLoader_v2.0是用C#实现的，是我在利用空余时间自学C#后写的，上面提到的功能都实现了。

        private void btnDownload_Click(object sender, EventArgs e)
        {
            btnDownload.Enabled = false;
            pBarLoading.Visible = false;
            if (!this.connect())
            {
                Debug.WriteLine("Udp server building unsuccessfully");
                textBoxStatus.ForeColor = Color.Red;
                textBoxStatus.AppendText("Udp server building unsuccessfully\r\n");
                textBoxStatus.ForeColor = Color.Black;
                btnDownload.Enabled = true;
                return;
            }

            try
            {
                loaderReader = new StreamReader(textBoxFile.Text);

            }
            catch (Exception ex)
            {
                Debug.WriteLine("Error: " + ex.Message);
                textBoxStatus.ForeColor = Color.Red;
                textBoxStatus.AppendText("Read hex file unsuccessfully\r\n");
                textBoxStatus.ForeColor = Color.Black;
                loaderReader.Close();
                loaderServer.Close();
                btnDownload.Enabled = true;
                return;
            }

            loaderFrame = new SerialFrame();
            DateTime startTime = DateTime.Now;
            IPEndPoint clientPoint = new IPEndPoint(IPAddress.Any, 0);
            
            if (!loaderServer.Read(readyMsg,timeSpan))
            {
                Debug.WriteLine("Error: Timeout receive ready message from bootloader");
                textBoxStatus.ForeColor = Color.Red;
                textBoxStatus.AppendText("Timeout receive ready message from bootloader\r\n");
                textBoxStatus.ForeColor = Color.Black;
                loaderServer.Close();
                loaderReader.Close();
                btnDownload.Enabled = true;
                return;
            }

            if (!erase())
            {
                textBoxStatus.ForeColor = Color.Red;
                textBoxStatus.AppendText("Erase unsuccessfully\r\n");
                textBoxStatus.ForeColor = Color.Black;
                loaderReader.Close();
                loaderServer.Close();
                btnDownload.Enabled = true;
                return;
            }

            pBarLoading.Refresh();
            pBarLoading.Visible = true;
            pBarLoading.Value = 0;
            pBarLoading.Maximum = loaderLines;
            pBarLoading.Step = 1;

            string recordLine;
            Address_U = 0;
            bool isNextLineUserID = false;
            bool isNextLineConfigBits = false;
            textBoxStatus.AppendText("\r\nDownloading hex file ...\r\n");
            try
            {
                while (loaderReader.Peek() >= 0)
                {
                    pBarLoading.PerformStep();
                    recordLine = loaderReader.ReadLine();

                    if (recordLine.Contains(EXTEND_TOKEN) == true)
                    {
                        if (recordLine.Contains(USER_ID_TOKEN) == true)
                        {
                            isNextLineUserID = true;
                            continue;
                        }
                        else if (recordLine.Contains(CONFIG_BITS_TOKEN) == true)
                        {
                            const int ADDR_U_START_INDEX = 9;
                            const int ADDR_U_LENGTH = 4;
                            string addrU = recordLine.Substring(ADDR_U_START_INDEX, ADDR_U_LENGTH);
                            Address_U = Convert.ToInt32(addrU, 16) << 16;
                            isNextLineConfigBits = true;
                            continue;
                        }
                        else
                        {
                            const int ADDR_U_START_INDEX = 9;
                            const int ADDR_U_LENGTH = 4;
                            string addrU = recordLine.Substring(ADDR_U_START_INDEX, ADDR_U_LENGTH);
                            Address_U = Convert.ToInt32(addrU, 16) << 16;
                            continue;
                        }
                    }
                    else if (((recordLine.Contains(J_TYPE_CONFIG_BITS_1) == true) ||
                             (recordLine.Contains(J_TYPE_CONFIG_BITS_2) == true) ||
                             (recordLine.Contains(J_TYPE_CONFIG_BITS_3) == true) ||
                             (recordLine.Contains(J_TYPE_CONFIG_BITS_4) == true) ||
                             (recordLine.Contains(J_TYPE_CONFIG_BITS_5) == true) ||
                             (recordLine.Contains(J_TYPE_CONFIG_BITS_6) == true) ||
                             (recordLine.Contains(J_TYPE_CONFIG_BITS_TOKEN_1) == true) ||
                             (recordLine.Contains(J_TYPE_CONFIG_BITS_TOKEN_2) == true)) &&
                             (Address_U == 0x010000))
                    {
                        if (!DownloadConfigLine(recordLine))
                        {
                            Debug.WriteLine("Error found during configuration bits programming");
                            loaderReader.Close();
                            loaderServer.Close();
                            btnDownload.Enabled = true;
                            return;
                        }
                        continue;
                    }
                    else if (recordLine.Contains(END_OF_HEX_FILE_TOKEN) == true)
                    {
                        break;
                    }
                    if (isNextLineUserID)
                    {
                        isNextLineUserID = false;
                        // do nothing;
                    }
                    else if (isNextLineConfigBits)
                    {
                        if (!DownloadConfigLine(recordLine))
                        {
                            Debug.WriteLine("Error found during configuration bits programming");
                            loaderReader.Close();
                            loaderServer.Close();
                            btnDownload.Enabled = true;
                            return;
                        }
                        isNextLineConfigBits = false;
                    }
                    else
                    {
                        if (!DownloadDataLine(recordLine))
                        {
                            Debug.WriteLine("Error found during data programming");
                            loaderReader.Close();
                            loaderServer.Close();
                            btnDownload.Enabled = true;
                            return;
                        }
                    }
                }
            }
            catch (Exception ex)
            {
                Debug.WriteLine("Error: " + ex.Message);
                textBoxStatus.ForeColor = Color.Red;
                textBoxStatus.AppendText("Downloading failed\r\n");
                textBoxStatus.ForeColor = Color.Black;
                loaderServer.Close();
                loaderReader.Close();
                btnDownload.Enabled = true;
                return;
            }
            textBoxStatus.AppendText("Downloading completed\r\n");

            if (!run())
            {
                textBoxStatus.ForeColor = Color.Red;
                textBoxStatus.AppendText("Jump to Application unsuccessfully\r\n");
                textBoxStatus.ForeColor = Color.Black;
                loaderReader.Close();
                loaderServer.Close();
                btnDownload.Enabled = true;
                return;
            }
            loaderServer.Close();
            loaderReader.Close();
            btnDownload.Enabled = true;
        }    

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