发送xmodem帧

Question

我有一个设备连接到串口并等待使用xmodem协议传输文件。

我尝试使用xmodem格式构建消息并发送它，但是我没有收到预期的传输ACK。

Bellow是代码的相关部分：

XMODEM消息的格式：

struct xmodem_packet 
{
    uint8_t start;
    uint8_t block;
    uint8_t block_neg;
    uint8_t payload[128];
    uint16_t crc;
};

打开并配置端口：

HANDLE portHandler = CreateFile(L"COM9", GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
    DCB config = { 0 };
    COMMTIMEOUTS timeout = { 0 };

    // Configure
    config.DCBlength = sizeof(config);
    GetCommState(portHandler, &config);
    config.BaudRate = CBR_115200;
    config.ByteSize = 8;
    config.StopBits = ONESTOPBIT;
    config.Parity = NOPARITY;
    SetCommState(portHandler, &config);
    timeout.ReadIntervalTimeout = 50;
    timeout.ReadTotalTimeoutConstant = 50;
    timeout.ReadTotalTimeoutMultiplier = 50;
    timeout.WriteTotalTimeoutConstant = 50;
    timeout.WriteTotalTimeoutMultiplier = 10;
    SetCommTimeouts(portHandler, &timeout);

为XMODEM传输准备模块：

    DWORD toRead = 1;
    DWORD wasWriten = 0;
    DWORD wasRead = 0;
    char responce = 0;
    WriteFile(portHandler, "set load xmodem\n", 3+4+6+3, &wasWriten, NULL);
    WriteFile(portHandler, "\n", 2, &wasWriten, NULL); // Doesn't work without this

构建XMODEM框架

xmodem_frame frame;
frame.start = SOH;
frame.block = 0;
frame.block_neg = 0;
memcpy(frame.payload, "test_data", 128);
swap16(crc16(frame.payload, sizeof(frame.payload)));

发送帧并查找ACK：

    WriteFile(portHandler, &frame, sizeof(frame), &wasWriten, NULL);
    ReadFile(portHandler, &responce, toRead, &wasRead, NULL);

    if (responce == 6)
        std::cout << "ACK was recieved";
    else
        std::cout << "ACK wasn't recieved";

我原本期待得到一个ACK，但总是会打印“未收到ACK”。