table of contents
|UCOM(4)||Device Drivers Manual||UCOM(4)|
ucom — USB tty
To compile this driver into the kernel, place the following line in your kernel configuration file:
Alternatively, to load the driver as a module at boot time, place the following line in loader.conf(5):
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 following variables are available as both sysctl(8) variables and loader(8) tunables:
- Debug output level, where 0 is debugging disabled and larger values increase debug message verbosity. Default is 0.
- When set to 1, the
ucomdriver will mark terminals as console devices when operating in device mode. Default is 1.
- Enables and configure PPS capture mode as described below.
Pulse Per Second (PPS) Timing Interface¶
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:
- Capture disabled (default).
- Capture pulses on the CTS line.
- Capture pulses on the DCD line.
- for callin ports
- corresponding callin initial-state and lock-state devices
- for callout ports
- corresponding callout initial-state and lock-state devices
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)
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.
Prior to FreeBSD 6.0
ucom created /dev/ucom?
rather than the uniform device names created today. Old scripts must be
|April 25, 2018||Debian|