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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 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 14.2-RELEASE July 11, 2020 FreeBSD 14.2-RELEASE