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<!-- Copyright (C) 2003 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 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
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TITLE="USB Enumeration Data"
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><HR
ALIGN="LEFT"
WIDTH="100%"></DIV
><H1
><A
NAME="USBS-START">Starting up a USB Device</H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN16210"
></A
><H2
>Name</H2
><TT
CLASS="FUNCTION"
>usbs_start</TT
>&nbsp;--&nbsp;Starting up a USB Device</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN16214"><H2
>Synopsis</H2
><DIV
CLASS="FUNCSYNOPSIS"
><A
NAME="AEN16215"><P
></P
><TABLE
BORDER="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><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="AEN16222"
></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="5"
BGCOLOR="#E0E0F0"
WIDTH="70%"
><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#AEN16552"
>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
SUMMARY="Footer navigation table"
WIDTH="100%"
BORDER="0"
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>Prev</A
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>Home</A
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><TR
><TD
WIDTH="33%"
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><TD
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VALIGN="top"
><A
HREF="io-usb-slave.html"
ACCESSKEY="U"
>Up</A
></TD
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WIDTH="33%"
ALIGN="right"
VALIGN="top"
>Devtab Entries</TD
></TR
></TABLE
></DIV
></BODY
></HTML
>

Line No.	Rev	Author	Line
1	28	unneback	`<!-- Copyright (C) 2003 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 the work or derivative of the work in any -->`
7			`<!-- standard (paper) book form is prohibited unless prior -->`
8			`<!-- permission is obtained from the copyright holder. -->`
9			`<HTML`
10			`><HEAD`
11			`><TITLE`
12			`>Starting up a USB Device</TITLE`
13			`><meta name="MSSmartTagsPreventParsing" content="TRUE">`
14			`<META`
15			`NAME="GENERATOR"`
16			`CONTENT="Modular DocBook HTML Stylesheet Version 1.76b+`
17			`"><LINK`
18			`REL="HOME"`
19			`TITLE="eCos Reference Manual"`
20			`HREF="ecos-ref.html"><LINK`
21			`REL="UP"`
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			`SUMMARY="Header navigation table"`
41			`WIDTH="100%"`
42			`BORDER="0"`
43			`CELLPADDING="0"`
44			`CELLSPACING="0"`
45			`><TR`
46			`><TH`
47			`COLSPAN="3"`
48			`ALIGN="center"`
49			`>eCos Reference Manual</TH`
50			`></TR`
51			`><TR`
52			`><TD`
53			`WIDTH="10%"`
54			`ALIGN="left"`
55			`VALIGN="bottom"`
56			`><A`
57			`HREF="usbs-enum.html"`
58			`ACCESSKEY="P"`
59			`>Prev</A`
60			`></TD`
61			`><TD`
62			`WIDTH="80%"`
63			`ALIGN="center"`
64			`VALIGN="bottom"`
65			`></TD`
66			`><TD`
67			`WIDTH="10%"`
68			`ALIGN="right"`
69			`VALIGN="bottom"`
70			`><A`
71			`HREF="usbs-devtab.html"`
72			`ACCESSKEY="N"`
73			`>Next</A`
74			`></TD`
75			`></TR`
76			`></TABLE`
77			`><HR`
78			`ALIGN="LEFT"`
79			`WIDTH="100%"></DIV`
80			`><H1`
81			`><A`
82			`NAME="USBS-START">Starting up a USB Device</H1`
83			`><DIV`
84			`CLASS="REFNAMEDIV"`
85			`><A`
86			`NAME="AEN16210"`
87			`></A`
88			`><H2`
89			`>Name</H2`
90			`><TT`
91			`CLASS="FUNCTION"`
92			`>usbs_start</TT`
93			`> -- Starting up a USB Device</DIV`
94			`><DIV`
95			`CLASS="REFSYNOPSISDIV"`
96			`><A`
97			`NAME="AEN16214"><H2`
98			`>Synopsis</H2`
99			`><DIV`
100			`CLASS="FUNCSYNOPSIS"`
101			`><A`
102			`NAME="AEN16215"><P`
103			`></P`
104			`><TABLE`
105			`BORDER="5"`
106			`BGCOLOR="#E0E0F0"`
107			`WIDTH="70%"`
108			`><TR`
109			`><TD`
110			`><PRE`
111			`CLASS="FUNCSYNOPSISINFO"`
112			`>#include <cyg/io/usb/usbs.h></PRE`
113			`></TD`
114			`></TR`
115			`></TABLE`
116			`><P`
117			`><CODE`
118			`><CODE`
119			`CLASS="FUNCDEF"`
120			`>void usbs_start</CODE`
121			`>(usbs_control_endpoint* ep0);</CODE`
122			`></P`
123			`><P`
124			`></P`
125			`></DIV`
126			`></DIV`
127			`><DIV`
128			`CLASS="REFSECT1"`
129			`><A`
130			`NAME="AEN16222"`
131			`></A`
132			`><H2`
133			`>Description</H2`
134			`><P`
135			`>Initializing a USB device requires some support from higher-level`
136			`code, typically the application, in the form of enumeration data.`
137			`Hence it is not possible for the low-level USB driver to activate a`
138			`USB device itself. Instead the higher-level code has to take care of`
139			`this by invoking <TT`
140			`CLASS="FUNCTION"`
141			`>usbs_start</TT`
142			`>. This function takes`
143			`a pointer to a USB control endpoint data structure. USB device drivers`
144			`should provide exactly one such data structure for every USB device,`
145			`so the pointer uniquely identifies the device.</P`
146			`><TABLE`
147			`BORDER="5"`
148			`BGCOLOR="#E0E0F0"`
149			`WIDTH="70%"`
150			`><TR`
151			`><TD`
152			`><PRE`
153			`CLASS="PROGRAMLISTING"`
154			`>const usbs_enumeration_data usb_enum_data = {`
155			`…`
156			`};`
157
158			`int`
159			`main(int argc, char** argv)`
160			`{`
161			`usbs_sa11x0_ep0.enumeration_data = &usb_enum_data;`
162			`…`
163			`usbs_start(&usbs_sa11x0_ep0);`
164			`…`
165			`}</PRE`
166			`></TD`
167			`></TR`
168			`></TABLE`
169			`><P`
170			`>The exact behaviour of <TT`
171			`CLASS="FUNCTION"`
172			`>usbs_start</TT`
173			`> depends on the`
174			`USB hardware and the device driver. A typical implementation would`
175			`change the USB data pins from tristated to active. If the peripheral`
176			`is already plugged into a host then the latter should detect this`
177			`change and start interacting with the peripheral, including requesting`
178			`the enumeration data. Some of this may happen before`
179			`<TT`
180			`CLASS="FUNCTION"`
181			`>usbs_start</TT`
182			`> returns, but given that multiple`
183			`interactions between USB host and peripheral are required it is likely`
184			`that the function will return before the peripheral is fully`
185			`configured. Control endpoints provide a <A`
186			`HREF="usbs-control.html#AEN16552"`
187			`>mechanism</A`
188			`> for informing`
189			`higher-level code of USB state changes.`
190			`<TT`
191			`CLASS="FUNCTION"`
192			`>usbs_start</TT`
193			`> will return even if the peripheral is`
194			`not currently connected to a host: it will not block until the`
195			`connection is established.</P`
196			`><P`
197			`><TT`
198			`CLASS="FUNCTION"`
199			`>usbs_start</TT`
200			`> should only be called once for a given`
201			`USB device. There are no defined error conditions. Note that the`
202			`function affects the entire USB device and not just the control`
203			`endpoint: there is no need to start any data endpoints as well.</P`
204			`></DIV`
205			`><DIV`
206			`CLASS="NAVFOOTER"`
207			`><HR`
208			`ALIGN="LEFT"`
209			`WIDTH="100%"><TABLE`
210			`SUMMARY="Footer navigation table"`
211			`WIDTH="100%"`
212			`BORDER="0"`
213			`CELLPADDING="0"`
214			`CELLSPACING="0"`
215			`><TR`
216			`><TD`
217			`WIDTH="33%"`
218			`ALIGN="left"`
219			`VALIGN="top"`
220			`><A`
221			`HREF="usbs-enum.html"`
222			`ACCESSKEY="P"`
223			`>Prev</A`
224			`></TD`
225			`><TD`
226			`WIDTH="34%"`
227			`ALIGN="center"`
228			`VALIGN="top"`
229			`><A`
230			`HREF="ecos-ref.html"`
231			`ACCESSKEY="H"`
232			`>Home</A`
233			`></TD`
234			`><TD`
235			`WIDTH="33%"`
236			`ALIGN="right"`
237			`VALIGN="top"`
238			`><A`
239			`HREF="usbs-devtab.html"`
240			`ACCESSKEY="N"`
241			`>Next</A`
242			`></TD`
243			`></TR`
244			`><TR`
245			`><TD`
246			`WIDTH="33%"`
247			`ALIGN="left"`
248			`VALIGN="top"`
249			`>USB Enumeration Data</TD`
250			`><TD`
251			`WIDTH="34%"`
252			`ALIGN="center"`
253			`VALIGN="top"`
254			`><A`
255			`HREF="io-usb-slave.html"`
256			`ACCESSKEY="U"`
257			`>Up</A`
258			`></TD`
259			`><TD`
260			`WIDTH="33%"`
261			`ALIGN="right"`
262			`VALIGN="top"`
263			`>Devtab Entries</TD`
264			`></TR`
265			`></TABLE`
266			`></DIV`
267			`></BODY`
268			`></HTML`
269			`>`

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[/] [openrisc/] [trunk/] [rtos/] [ecos-2.0/] [doc/] [html/] [ref/] [usbs-start.html] - Blame information for rev 174