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

NAME
     ucom - USB tty support

SYNOPSIS
     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):

           ucom_load="YES"

DESCRIPTION
     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.

SYSCTL VARIABLES
     The following variables are available as both sysctl(8) variables and
     loader(8) tunables:

     hw.usb.ucom.debug
             Debug output level, where 0 is debugging disabled and larger
             values increase debug message verbosity.  Default is 0.

     hw.usb.ucom.device_mode_console
             When set to 1, the ucom driver will mark terminals as console
             devices when operating in device mode.  Default is 1.

     hw.usb.ucom.pps_mode
             Enables and configure PPS capture mode as described below.

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
     /dev/pps0.

     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.

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

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

SEE ALSO
     cu(1), 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), ttys(5)

HISTORY
     The ucom driver was adopted from NetBSD in March of 2002.  This manual
     page was adopted from NetBSD by Tom Rhodes <trhodes@FreeBSD.org> in April
     2002.

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

FreeBSD 13.1-RELEASE-p6          July 11, 2020         FreeBSD 13.1-RELEASE-p6