如何在不更改任何引脚的情况下在linux中打开串口? [英] How to open serial port in linux without changing any pin?

问题描述

Posix 需要在端口打开时更改 RTS 引脚.我想要一种方法来避免它.

Posix requires changing RTS pin on port opening. I want a way to avoid it.

推荐答案

遇到同样的问题，我会尝试通过修补 ftdi_sio 内核驱动程序.您只需要像这样在 ftdi_dtr_rts() 中取消注释一小段代码:

Having the same problem, I'd give it a try by patching the ftdi_sio kernel driver. You just need to uncomment a small piece of code in ftdi_dtr_rts() like this:

static void ftdi_dtr_rts(struct usb_serial_port *port, int on) {
    ...
    /* drop RTS and DTR */
    if (on)
        set_mctrl(port, TIOCM_DTR /*| TIOCM_RTS*/);    // <<-- HERE
    else
        clear_mctrl(port, TIOCM_DTR /*| TIOCM_RTS*/);  // <<-- and HERE
}

并且 RTS 握手线在 open() 调用时不再更改.请注意，只要加载了修改后的内核驱动程序，uart 就可能不再使用 RTS/CTS 硬件握手.但是您仍然可以通过调用例如手动控制 RTS 握手线的状态:

and the RTS handshake line is not longer changed upon open() call. Note, that the uart than might not longer working with RTS/CTS hardware handshake, as long as your modified kernel driver is loaded. But you can still control the state of the RTS handshake line manually by calling e.g.:

    int opins = TIOCM_RTS;
    ioctl(tty_fd, TIOCMBIC, &opins);

我使用 picocom 2.3a 的 Ctrl+A+G 命令对此进行了测试，运行 Kubuntu 16.04 64 位和 Ftdi FT2232H 基于 USB uart 适配器.

I'd tested this with the Ctrl+A+G command of picocom 2.3a, running Kubuntu 16.04 64 bit and Ftdi FT2232H based usb uart adapter.

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