1 .\" Copyright (c) 1997, 1998 Nick Hibma <n_hibma@FreeBSD.org>
2 .\" Copyright (c) 2008 Hans Petter Selasky. All rights reserved.
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32 .Nd Universal Serial Bus
34 To compile this driver into the kernel,
35 place the following line in your
36 kernel configuration file:
37 .Bd -ragged -offset indent
41 Alternatively, to load the driver as a
42 module at boot time, place the following line in
44 .Bd -literal -offset indent
47 .Sh USERLAND PROGRAMMING
48 USB functions can be accessed from userland through the libusb library.
54 provides machine-independent bus support and drivers for
56 devices in host and device side mode.
60 driver has three layers:
61 .Bl -tag -width 6n -offset indent
62 .It USB Controller (Bus)
67 The controller attaches to a physical bus
72 bus attaches to the controller, and the root hub attaches
74 Any devices attached to the bus will attach to the root hub
75 or another hub attached to the
81 device will always be present as it is needed for the
83 .Sh INTRODUCTION TO USB
86 is a system where external devices can be connected to a PC.
87 The most common USB speeds are:
88 .Bl -tag -width 6n -offset indent
89 .It Low Speed (1.5MBit/sec)
90 .It Full Speed (12MBit/sec)
91 .It High Speed (480MBit/sec)
96 has a USB controller that is the master of the bus.
97 The physical communication is simplex which means the host controller only communicates with one USB device at a time.
99 There can be up to 127 devices connected to an USB HUB tree.
100 The addresses are assigned
101 dynamically by the host when each device is attached to the bus.
103 Within each device there can be up to 16 endpoints.
105 is individually addressed and the addresses are static.
106 Each of these endpoints will communicate in one of four different modes:
107 .Em control , isochronous , bulk ,
110 A device always has at least one endpoint.
111 This endpoint has address 0 and is a control
112 endpoint and is used to give commands to and extract basic data,
113 such as descriptors, from the device.
114 Each endpoint, except the control endpoint, is unidirectional.
116 The endpoints in a device are grouped into interfaces.
117 An interface is a logical unit within a device; e.g.\&
118 a compound device with both a keyboard and a trackball would present
119 one interface for each.
120 An interface can sometimes be set into different modes,
121 called alternate settings, which affects how it operates.
122 Different alternate settings can have different endpoints
125 A device may operate in different configurations.
127 configuration, the device may present different sets of endpoints
130 The bus enumeration of the
132 bus proceeds in several steps:
135 Any interface specific driver can attach to the device.
137 If none is found, generic interface class drivers can attach.
142 specifications can be found at:
144 .D1 Pa http://www.usb.org/developers/docs/
174 module complies with the USB 2.0 standard.
178 module has been inspired by the NetBSD USB stack initially written by
179 Lennart Augustsson. The
181 module was written by
182 .An Hans Petter Selasky Aq hselasky@FreeBSD.org .