如何连接不公开串行接口的 USB 设备？

Question

I want to make a custom program that will allow me to interface a Salae Logic usb logic analyzer. So first and foremost I looked upon for any info regarding the usb in my linux box:

$ lsusb
Bus 002 Device 002: ID 05e3:0732 Genesys Logic, Inc. All-in-One Cardreader
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 1a40:0101 Terminus Technology Inc. Hub
Bus 001 Device 002: ID 4e53:5407  
Bus 001 Device 004: ID 0925:3881 Lakeview Research Saleae Logic
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Dmesg:

[  428.549560] usb 1-6: new high-speed USB device number 4 using xhci_hcd
[  428.697722] usb 1-6: New USB device found, idVendor=0925, idProduct=3881, bcdDevice= 0.01
[  428.697727] usb 1-6: New USB device strings: Mfr=0, Product=0, SerialNumber=0

Is seems that does not expose a serial device like arduino (or any other FTDI interfacing device) like modems:

[  766.906266] usb 1-5: new full-speed USB device number 5 using xhci_hcd
[  767.056746] usb 1-5: New USB device found, idVendor=2341, idProduct=0043, bcdDevice= 0.01
[  767.056752] usb 1-5: New USB device strings: Mfr=1, Product=2, SerialNumber=220
[  767.056756] usb 1-5: Manufacturer: Arduino (www.arduino.cc)
[  767.056759] usb 1-5: SerialNumber: 7533131313335170A061
[  767.088804] cdc_acm 1-5:1.0: ttyACM0: USB ACM device
[  767.089110] usbcore: registered new interface driver cdc_acm
[  767.089110] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters

So supposedly I want to make a C++ (or any other language) software where I can read data from it how I can make my application to have access to a non usb-to-serial interfacing device?

I mean for an arduino I could use the POSIX open as the example shows from this link :

    #include <stdio.h>   /* Standard input/output definitions */
    #include <string.h>  /* String function definitions */
    #include <unistd.h>  /* UNIX standard function definitions */
    #include <fcntl.h>   /* File control definitions */
    #include <errno.h>   /* Error number definitions */
    #include <termios.h> /* POSIX terminal control definitions */

    /*
     * 'open_port()' - Open serial port 1.
     *
     * Returns the file descriptor on success or -1 on error.
     */
    int open_port(void){
      int fd; /* File descriptor for the port */


      fd = open("/dev/ttyACM0", O_RDWR | O_NOCTTY | O_NDELAY);
      if (fd == -1)
      {
       /*
        * Could not open the port.
        */
        perror("open_port: Unable to open /dev/ttyS0 - ");
      } else{ 
        fcntl(fd, F_SETFL, 0); 
      }

      return (fd);
    }

But in my case I have no such a file descriptor to begin with according to dmesg .

Answer 1

Normally something like this is done with libusb, at least when you are in userspace (which your question suggests you are).

USB transfers are a lot more complicated than a USB UART though, so brace yourself to deal with different endpoints, pipes, transfer modes and co