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UCOM(4)                FreeBSD Kernel Interfaces Manual                UCOM(4)

     ucom - USB tty support

     To compile this driver into the kernel, place the following line in your
     kernel configuration file:

           device ucom

     Alternatively, to load the driver as a module at boot time, place the
     following line in loader.conf(5):


     The ucom driver attaches to USB modems, serial ports, and other devices
     that need to look like a tty.  The ucom driver shows a behavior like a
     tty(4).  This means that normal programs such as tip(1) or ppp(8) can be
     used to access the device.

Pulse Per Second (PPS) Timing Interface
     The ucom driver can capture PPS timing information as defined in RFC
     2783.  The API, accessed via ioctl(2), is available on the tty device.
     To use the PPS capture feature with ntpd(8), symlink the tty device to

     The hw.usb.ucom.pps_mode sysctl configures the PPS capture mode.  It can
     be set in loader.conf(5) or sysctl.conf(5).  The following capture modes
     are available:
         0     Capture disabled (default).
         1     Capture pulses on the CTS line.
         2     Capture pulses on the DCD line.

     /dev/ttyU*       for callin ports
     /dev/ttyU*.lock  corresponding callin initial-state and lock-state

     /dev/cuaU*       for callout ports
     /dev/cuaU*.lock  corresponding callout initial-state and lock-state

     tty(4), uark(4), ubsa(4), ubser(4), uchcom(4), ucycom(4), ufoma(4),
     uftdi(4), uhso(4), uipaq(4), umcs(4), umct(4), umodem(4), umoscom(4),
     uplcom(4), usb(4), uslcom(4), uvisor(4), uvscom(4)

     The ucom driver was adopted from NetBSD in March of 2002.  This manual
     page was adopted from NetBSD by Tom Rhodes <[email protected]> in April

     Prior to FreeBSD 6.0 ucom created /dev/ucom? rather than the uniform
     device names created today.  Old scripts must be adjusted accordingly.

FreeBSD 11.1-RELEASE-p4         April 26, 2017         FreeBSD 11.1-RELEASE-p4
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