---
name: "uchcom"
section: "4"
platform: "freebsd"
package: "base"
version: "16.0-CURRENT-20261027-61c70dc16a79"
release: "FreeBSD 16.0-CURRENT (2026-10-27)"
platforms: ["freebsd", "openbsd"]
url: "https://new.carta.tech/uchcom"
---

# uchcom(4)

WinChipHead CH9102/CH343/CH341/CH340 USB to serial UART driver

## NAME

**uchcom** – WinChipHead CH9102/CH343/CH341/CH340 USB to serial UART driver

## SYNOPSIS

**device usb** **device ucom** **device uchcom**

In [rc.conf(5)](/rc.conf/5.md): **kld\_list="uchcom"**

In [sysctl.conf(5)](/sysctl.conf/5.md): **hw.usb.uchcom.debug=1**

## DESCRIPTION

The **uchcom** driver provides support for the WinChipHead USB to serial UART adapters. If the appropriate hardware is detected, the driver will be loaded automatically by [devmatch(8)](/devmatch/8.md). To load the driver manually, add it to the **kld\_list** in [rc.conf(5)](/rc.conf/5.md), or use [kldload(8)](/kldload/8.md) at runtime. The device is accessed through the [ucom(4)](/ucom/4.md) driver, which makes it behave like a [tty(4)](/tty/4.md).

Call out through this interface with applications like [cu(1)](/cu/1.md) or [tip(1)](/tip/1.md).

## HARDWARE

The **uchcom** driver supports the following USB to serial UART controllers:

- WinChipHead CH9102 (max 6Mbps)

- WinChipHead CH343 (max 6Mbps)

- WinChipHead CH341 (max 2Mbps)

- WinChipHead CH340 (max 2Mbps)

## SYSCTL VARIABLES

These settings can be entered in the [loader(8)](/loader/8.md) prompt, set in [loader.conf(5)](/loader.conf/5.md), [sysctl.conf(5)](/sysctl.conf/5.md), or changed at runtime with [sysctl(8)](/sysctl/8.md):

- *hw.usb.uchcom.debug*

  Enable debugging messages, default ‘0’

## 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)](/cu/1.md), [tty(4)](/tty/4.md), [ucom(4)](/ucom/4.md), [usb(4)](/usb/4.md)

## HISTORY

The **uchcom** driver appeared in FreeBSD 8.0 from NetBSD 5.0.