章 25. USB Device Mode / USB OTG
前一頁 | 部 III. 系統管理 | 下一頁

## 章 25. USB Device Mode / USB OTG

## 25.1. 概述

Written by Edward Tomasz Napierala.

This chapter covers the use of USB Device Mode and USB On The Go (USB OTG) in FreeBSD. This includes virtual serial consoles, virtual network interfaces, and virtual USB drives.

When running on hardware that supports USB device mode or USB OTG, like that built into many embedded boards, the FreeBSD USB stack can run in device mode. Device mode makes it possible for the computer to present itself as different kinds of USB device classes, including serial ports, network adapters, and mass storage, or a combination thereof. A USB host like a laptop or desktop computer is able to access them just like physical USB devices. Device mode is sometimes called the “USB gadget mode”.

There are two basic ways the hardware can provide the device mode functionality: with a separate "client port", which only supports the device mode, and with a USB OTG port, which can provide both device and host mode. For USB OTG ports, the USB stack switches between host-side and device-side automatically, depending on what is connected to the port. Connecting a USB device like a memory stick to the port causes FreeBSD to switch to host mode. Connecting a USB host like a computer causes FreeBSD to switch to device mode. Single purpose "client ports" always work in device mode.

What FreeBSD presents to the USB host depends on the `hw.usb.template` sysctl. Some templates provide a single device, such as a serial terminal; others provide multiple ones, which can all be used at the same time. An example is the template 10, which provides a mass storage device, a serial console, and a network interface. See usb_template(4) for the list of available values.

Note that in some cases, depending on the hardware and the hosts operating system, for the host to notice the configuration change, it must be either physically disconnected and reconnected, or forced to rescan the USB bus in a system-specific way. When FreeBSD is running on the host, usbconfig(8) `reset` can be used. This also must be done after loading `usb_template.ko` if the USB host was already connected to the USB OTG socket.

讀完這章，您將了解︰

- How to set up USB Device Mode functionality on FreeBSD.

- How to configure the virtual serial port on FreeBSD.

- How to connect to the virtual serial port from various operating systems.

- How to configure FreeBSD to provide a virtual USB network interface.

- How to configure FreeBSD to provide a virtual USB storage device.

前一頁 | 上一層 | 下一頁
24.4. 使用 DTrace | 起始頁 | 25.2. USB Virtual Serial Ports

本文及其他文件，可由此下載： ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/。

若有 FreeBSD 方面疑問，請先閱讀 FreeBSD 相關文件，如不能解決的話，再洽詢 <questions@FreeBSD.org>。
關於本文件的問題，請洽詢 <doc@FreeBSD.org>。