串口通讯-PuTTY仿真

Question

I am writing a simple user interface to communicate with an In-Circuit Serial Programmer. The intention is to remove the need for the end-user to type over a dozen cryptic commands via PuTTY, and in fact to remove the need for typing altogether as the user is inevitably wearing keyboard-unfriendly gloves. The process requires interaction with the user, so a simple batch script is not feasible.

I can find the correct COM port and successfully open it. I can send data, but the response is only ever the equivalent of "unknown command".

I shall refrain from posting the whole code as nobody will be able to recreate my circumstances. However, I can always add everything if necessary.

I open comms using CreateFile() and use WriteFile() or ReadFile() to communicate. For example:

if (!WriteFile(hSerial, "r rc.all\r\n", 10, &bytesRead, NULL))
    cout << "Error sending message (" << GetLastError() << ")" << endl;
if (!ReadFile(hSerial, msgBuffer, 15, &bytesRead, NULL))
    cout << "No message received" << endl
else
{
    cout << "Bytes rcvd = " << bytesRead << endl;
    for (int x=0; x<bytesRead; x++)
        cout << (unsigned int) msgBuffer[x] << "  ";
}

No matter what message I send (either "r rc.all" or "foobar") I always get the same response:

Bytes rcvd = 3
62  13  10

Which is >\\r\\n . I have tried slowing down the sending of characters to simulate them being typed, but this invokes the same response from the ICSP:

bool serialSend(LPCSTR MESSAGE, PHANDLE hSERIAL)
{
    DWORD   bytesWritten;
    char    writeBuff[2];    

    writeBuff[1] = '\0';

    for (UINT x = 0; x <= strnlen(MESSAGE, 64); x++)
    {
        cout << MESSAGE[x];
        writeBuff[0] = MESSAGE[x];
        if (!WriteFile(*hSERIAL, writeBuff, 1, &bytesWritten, NULL))
            cout << "\t\tERROR! (character '" << MESSAGE[x] << "', error " << GetLastError() << ")" << endl;
        Sleep(100);
    }

    writeBuff[0] = '\n';
    if (!WriteFile(*hSERIAL, writeBuff, 1, &bytesWritten, NULL))
        cout << "\t\tERROR! (character 'LF', error " << GetLastError() << ")" << endl;
    Sleep(100);
    writeBuff[0] = '\r';
    if (!WriteFile(*hSERIAL, writeBuff, 1, &bytesWritten, NULL))
        cout << "\t\tERROR! (character 'CR', error " << GetLastError() << ")" << endl;

    cout << endl;

    return true;
}

I have set the parameters of the serial connection to match the settings in PuTTY - Byte length, stop bit, parity, flow control, etc. The fact that I get a response at all suggests the connections is not at fault.

What is wrong?

Answer 1

The problem turned out to be the \\r\\n combination sent at the end of the message.

Sending just \\r or just \\n does not work. However, sending (char) 13 does - even though that should be the same as \\r .

There also needs to be a pause between the sending of each character; 1ms is sufficient.