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<!-- Copyright (C) 2002 Red Hat, Inc.                                -->
<!-- This material may be distributed only subject to the terms      -->
<!-- and conditions set forth in the Open Publication License, v1.0  -->
<!-- or later (the latest version is presently available at          -->
<!-- http://www.opencontent.org/openpub/).                           -->
<!-- Distribution of substantively modified versions of this         -->
<!-- document is prohibited without the explicit permission of the   -->
<!-- copyright holder.                                               -->
<!-- Distribution of the work or derivative of the work in any       -->
<!-- standard (paper) book form is prohibited unless prior           -->
<!-- permission is obtained from the copyright holder.               -->
<HTML
><HEAD
><TITLE
>Starting up a USB Device</TITLE
><meta name="MSSmartTagsPreventParsing" content="TRUE">
<META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.64
"><LINK
REL="HOME"
TITLE="eCos USB Slave Support"
HREF="io-usb-slave.html"><LINK
REL="PREVIOUS"
TITLE="USB Enumeration Data"
HREF="usbs-enum.html"><LINK
REL="NEXT"
TITLE="Devtab Entries"
HREF="usbs-devtab.html"></HEAD
><BODY
CLASS="REFENTRY"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><DIV
CLASS="NAVHEADER"
><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TH
COLSPAN="3"
ALIGN="center"
>eCos USB Slave Support</TH
></TR
><TR
><TD
WIDTH="10%"
ALIGN="left"
VALIGN="bottom"
><A
HREF="usbs-enum.html"
>Prev</A
></TD
><TD
WIDTH="80%"
ALIGN="center"
VALIGN="bottom"
></TD
><TD
WIDTH="10%"
ALIGN="right"
VALIGN="bottom"
><A
HREF="usbs-devtab.html"
>Next</A
></TD
></TR
></TABLE
><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><H1
><A
NAME="USBS-START"
>Starting up a USB Device</A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN173"
></A
><H2
>Name</H2
><TT
CLASS="FUNCTION"
>usbs_start</TT
>&nbsp;--&nbsp;Starting up a USB Device</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN177"
></A
><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN178"
></A
><P
></P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="FUNCSYNOPSISINFO"
>#include &lt;cyg/io/usb/usbs.h&gt;</PRE
></TD
></TR
></TABLE
><P
><CODE
><CODE
CLASS="FUNCDEF"
>void usbs_start</CODE
>(usbs_control_endpoint* ep0);</CODE
></P
><P
></P
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN185"
></A
><H2
>Description</H2
><P
>Initializing a USB device requires some support from higher-level
code, typically the application, in the form of enumeration data.
Hence it is not possible for the low-level USB driver to activate a
USB device itself. Instead the higher-level code has to take care of
this by invoking <TT
CLASS="FUNCTION"
>usbs_start</TT
>. This function takes
a pointer to a USB control endpoint data structure. USB device drivers
should provide exactly one such data structure for every USB device,
so the pointer uniquely identifies the device.</P
><TABLE
BORDER="0"
BGCOLOR="#E0E0E0"
WIDTH="100%"
><TR
><TD
><PRE
CLASS="PROGRAMLISTING"
>const usbs_enumeration_data usb_enum_data = {
    &#8230;
};
 
int
main(int argc, char** argv)
{
    usbs_sa11x0_ep0.enumeration_data = &amp;usb_enum_data;
    &#8230;
    usbs_start(&amp;usbs_sa11x0_ep0);
    &#8230;
}</PRE
></TD
></TR
></TABLE
><P
>The exact behaviour of <TT
CLASS="FUNCTION"
>usbs_start</TT
> depends on the
USB hardware and the device driver. A typical implementation would
change the USB data pins from tristated to active. If the peripheral
is already plugged into a host then the latter should detect this
change and start interacting with the peripheral, including requesting
the enumeration data. Some of this may happen before
<TT
CLASS="FUNCTION"
>usbs_start</TT
> returns, but given that multiple
interactions between USB host and peripheral are required it is likely
that the function will return before the peripheral is fully
configured. Control endpoints provide a <A
HREF="usbs-control.html#AEN515"
>mechanism</A
> for informing
higher-level code of USB state changes.
<TT
CLASS="FUNCTION"
>usbs_start</TT
> will return even if the peripheral is
not currently connected to a host: it will not block until the
connection is established.</P
><P
><TT
CLASS="FUNCTION"
>usbs_start</TT
> should only be called once for a given
USB device. There are no defined error conditions. Note that the
function affects the entire USB device and not just the control
endpoint: there is no need to start any data endpoints as well.</P
></DIV
><DIV
CLASS="NAVFOOTER"
><HR
ALIGN="LEFT"
WIDTH="100%"><TABLE
WIDTH="100%"
BORDER="0"
CELLPADDING="0"
CELLSPACING="0"
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
><A
HREF="usbs-enum.html"
>Prev</A
></TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
><A
HREF="io-usb-slave.html"
>Home</A
></TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
><A
HREF="usbs-devtab.html"
>Next</A
></TD
></TR
><TR
><TD
WIDTH="33%"
ALIGN="left"
VALIGN="top"
>USB Enumeration Data</TD
><TD
WIDTH="34%"
ALIGN="center"
VALIGN="top"
>&nbsp;</TD
><TD
WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Devtab Entries</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>

Line No.	Rev	Author	Line
1	27	unneback	`<!-- Copyright (C) 2002 Red Hat, Inc. -->`
2			`<!-- This material may be distributed only subject to the terms -->`
3			`<!-- and conditions set forth in the Open Publication License, v1.0 -->`
4			`<!-- or later (the latest version is presently available at -->`
5			`<!-- http://www.opencontent.org/openpub/). -->`
6			`<!-- Distribution of substantively modified versions of this -->`
7			`<!-- document is prohibited without the explicit permission of the -->`
8			`<!-- copyright holder. -->`
9			`<!-- Distribution of the work or derivative of the work in any -->`
10			`<!-- standard (paper) book form is prohibited unless prior -->`
11			`<!-- permission is obtained from the copyright holder. -->`
12			`<HTML`
13			`><HEAD`
14			`><TITLE`
15			`>Starting up a USB Device</TITLE`
16			`><meta name="MSSmartTagsPreventParsing" content="TRUE">`
17			`<META`
18			`NAME="GENERATOR"`
19			`CONTENT="Modular DocBook HTML Stylesheet Version 1.64`
20			`"><LINK`
21			`REL="HOME"`
22			`TITLE="eCos USB Slave Support"`
23			`HREF="io-usb-slave.html"><LINK`
24			`REL="PREVIOUS"`
25			`TITLE="USB Enumeration Data"`
26			`HREF="usbs-enum.html"><LINK`
27			`REL="NEXT"`
28			`TITLE="Devtab Entries"`
29			`HREF="usbs-devtab.html"></HEAD`
30			`><BODY`
31			`CLASS="REFENTRY"`
32			`BGCOLOR="#FFFFFF"`
33			`TEXT="#000000"`
34			`LINK="#0000FF"`
35			`VLINK="#840084"`
36			`ALINK="#0000FF"`
37			`><DIV`
38			`CLASS="NAVHEADER"`
39			`><TABLE`
40			`WIDTH="100%"`
41			`BORDER="0"`
42			`CELLPADDING="0"`
43			`CELLSPACING="0"`
44			`><TR`
45			`><TH`
46			`COLSPAN="3"`
47			`ALIGN="center"`
48			`>eCos USB Slave Support</TH`
49			`></TR`
50			`><TR`
51			`><TD`
52			`WIDTH="10%"`
53			`ALIGN="left"`
54			`VALIGN="bottom"`
55			`><A`
56			`HREF="usbs-enum.html"`
57			`>Prev</A`
58			`></TD`
59			`><TD`
60			`WIDTH="80%"`
61			`ALIGN="center"`
62			`VALIGN="bottom"`
63			`></TD`
64			`><TD`
65			`WIDTH="10%"`
66			`ALIGN="right"`
67			`VALIGN="bottom"`
68			`><A`
69			`HREF="usbs-devtab.html"`
70			`>Next</A`
71			`></TD`
72			`></TR`
73			`></TABLE`
74			`><HR`
75			`ALIGN="LEFT"`
76			`WIDTH="100%"></DIV`
77			`><H1`
78			`><A`
79			`NAME="USBS-START"`
80			`>Starting up a USB Device</A`
81			`></H1`
82			`><DIV`
83			`CLASS="REFNAMEDIV"`
84			`><A`
85			`NAME="AEN173"`
86			`></A`
87			`><H2`
88			`>Name</H2`
89			`><TT`
90			`CLASS="FUNCTION"`
91			`>usbs_start</TT`
92			`> -- Starting up a USB Device</DIV`
93			`><DIV`
94			`CLASS="REFSYNOPSISDIV"`
95			`><A`
96			`NAME="AEN177"`
97			`></A`
98			`><H2`
99			`>Synopsis</H2`
100			`><DIV`
101			`CLASS="FUNCSYNOPSIS"`
102			`><A`
103			`NAME="AEN178"`
104			`></A`
105			`><P`
106			`></P`
107			`><TABLE`
108			`BORDER="0"`
109			`BGCOLOR="#E0E0E0"`
110			`WIDTH="100%"`
111			`><TR`
112			`><TD`
113			`><PRE`
114			`CLASS="FUNCSYNOPSISINFO"`
115			`>#include <cyg/io/usb/usbs.h></PRE`
116			`></TD`
117			`></TR`
118			`></TABLE`
119			`><P`
120			`><CODE`
121			`><CODE`
122			`CLASS="FUNCDEF"`
123			`>void usbs_start</CODE`
124			`>(usbs_control_endpoint* ep0);</CODE`
125			`></P`
126			`><P`
127			`></P`
128			`></DIV`
129			`></DIV`
130			`><DIV`
131			`CLASS="REFSECT1"`
132			`><A`
133			`NAME="AEN185"`
134			`></A`
135			`><H2`
136			`>Description</H2`
137			`><P`
138			`>Initializing a USB device requires some support from higher-level`
139			`code, typically the application, in the form of enumeration data.`
140			`Hence it is not possible for the low-level USB driver to activate a`
141			`USB device itself. Instead the higher-level code has to take care of`
142			`this by invoking <TT`
143			`CLASS="FUNCTION"`
144			`>usbs_start</TT`
145			`>. This function takes`
146			`a pointer to a USB control endpoint data structure. USB device drivers`
147			`should provide exactly one such data structure for every USB device,`
148			`so the pointer uniquely identifies the device.</P`
149			`><TABLE`
150			`BORDER="0"`
151			`BGCOLOR="#E0E0E0"`
152			`WIDTH="100%"`
153			`><TR`
154			`><TD`
155			`><PRE`
156			`CLASS="PROGRAMLISTING"`
157			`>const usbs_enumeration_data usb_enum_data = {`
158			`…`
159			`};`
160
161			`int`
162			`main(int argc, char** argv)`
163			`{`
164			`usbs_sa11x0_ep0.enumeration_data = &usb_enum_data;`
165			`…`
166			`usbs_start(&usbs_sa11x0_ep0);`
167			`…`
168			`}</PRE`
169			`></TD`
170			`></TR`
171			`></TABLE`
172			`><P`
173			`>The exact behaviour of <TT`
174			`CLASS="FUNCTION"`
175			`>usbs_start</TT`
176			`> depends on the`
177			`USB hardware and the device driver. A typical implementation would`
178			`change the USB data pins from tristated to active. If the peripheral`
179			`is already plugged into a host then the latter should detect this`
180			`change and start interacting with the peripheral, including requesting`
181			`the enumeration data. Some of this may happen before`
182			`<TT`
183			`CLASS="FUNCTION"`
184			`>usbs_start</TT`
185			`> returns, but given that multiple`
186			`interactions between USB host and peripheral are required it is likely`
187			`that the function will return before the peripheral is fully`
188			`configured. Control endpoints provide a <A`
189			`HREF="usbs-control.html#AEN515"`
190			`>mechanism</A`
191			`> for informing`
192			`higher-level code of USB state changes.`
193			`<TT`
194			`CLASS="FUNCTION"`
195			`>usbs_start</TT`
196			`> will return even if the peripheral is`
197			`not currently connected to a host: it will not block until the`
198			`connection is established.</P`
199			`><P`
200			`><TT`
201			`CLASS="FUNCTION"`
202			`>usbs_start</TT`
203			`> should only be called once for a given`
204			`USB device. There are no defined error conditions. Note that the`
205			`function affects the entire USB device and not just the control`
206			`endpoint: there is no need to start any data endpoints as well.</P`
207			`></DIV`
208			`><DIV`
209			`CLASS="NAVFOOTER"`
210			`><HR`
211			`ALIGN="LEFT"`
212			`WIDTH="100%"><TABLE`
213			`WIDTH="100%"`
214			`BORDER="0"`
215			`CELLPADDING="0"`
216			`CELLSPACING="0"`
217			`><TR`
218			`><TD`
219			`WIDTH="33%"`
220			`ALIGN="left"`
221			`VALIGN="top"`
222			`><A`
223			`HREF="usbs-enum.html"`
224			`>Prev</A`
225			`></TD`
226			`><TD`
227			`WIDTH="34%"`
228			`ALIGN="center"`
229			`VALIGN="top"`
230			`><A`
231			`HREF="io-usb-slave.html"`
232			`>Home</A`
233			`></TD`
234			`><TD`
235			`WIDTH="33%"`
236			`ALIGN="right"`
237			`VALIGN="top"`
238			`><A`
239			`HREF="usbs-devtab.html"`
240			`>Next</A`
241			`></TD`
242			`></TR`
243			`><TR`
244			`><TD`
245			`WIDTH="33%"`
246			`ALIGN="left"`
247			`VALIGN="top"`
248			`>USB Enumeration Data</TD`
249			`><TD`
250			`WIDTH="34%"`
251			`ALIGN="center"`
252			`VALIGN="top"`
253			`> </TD`
254			`><TD`
255			`WIDTH="33%"`
256			`ALIGN="right"`
257			`VALIGN="top"`
258			`>Devtab Entries</TD`
259			`></TR`
260			`></TABLE`
261			`></DIV`
262			`></BODY`
263			`></HTML`
264			`>`

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[/] [openrisc/] [trunk/] [rtos/] [ecos-2.0/] [packages/] [io/] [usb/] [slave/] [v2_0/] [doc/] [usbs-start.html] - Blame information for rev 252