采用TCP协议实现PIC18F97J60 ethernet bootloader

　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

...

　　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 unsuccessfullyrn");

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 unsuccessfullyrn");

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 bootloaderrn");

textBoxStatus.ForeColor = Color.Black;

loaderServer.Close();

loaderReader.Close();

btnDownload.Enabled = true;

return;

}

if (!erase())

{

textBoxStatus.ForeColor = Color.Red;

textBoxStatus.AppendText("Erase unsuccessfullyrn");

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("rnDownloading hex file ...rn");

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;