DS785UM1
11-5
Copyright 2007 Cirrus Logic
Universal Serial Bus Host Controller
EP93xx User’s Guide
1
1
1
1
11
scheduling the Endpoint Descriptor at the appropriate depth in the tree. The higher the polling
rate, the closer to the root of the tree the Endpoint Descriptor will be placed since multiple
lists will converge on it.
illustrates the structure for Interrupt Endpoints. The
Interrupt Endpoint Descriptor Placeholder indicates where zero or more Endpoint Descriptors
may be enqueued. The numbers on the left are the index into the HCCA interrupt head
pointer array.
Figure 11-4. Interrupt Endpoint Descriptor Structure
is a sample Interrupt Endpoint schedule. The schedule shows one Endpoint
Descriptors at a 1 ms poll interval, two Endpoint Descriptors at a 2 ms poll interval, one
Endpoint at a 4 ms poll interval, two Endpoint Descriptors at an 8 ms poll interval, two
Endpoint Descriptors at a 16 ms poll interval, and two Endpoint Descriptors at a 32 ms poll
interval. Note that in this example unused Interrupt Endpoint Placeholders are bypassed and
the link is connected to the next available Endpoint in the hierarchy.
0
16
8
24
4
20
12
28
2
18
10
26
6
22
14
30
1
17
9
25
5
21
13
29
3
19
11
27
7
23
15
31
Interrupt
Head
Pointers
32
16
8
4
2
1
Interrupt Endpoint Descriptor Placeholders
Endpoint Poll Interval (ms)
Summary of Contents for EP93 Series
Page 28: ...P 6 DS785UM1 Copyright 2007 Cirrus Logic Preface EP93xx User s Guide PP P ...
Page 162: ...5 36 DS785UM1 Copyright 2007 Cirrus Logic System Controller EP93xx User s Guide 55 5 ...
Page 576: ...15 18 DS785UM1 Copyright 2007 Cirrus Logic UART2 EP93xx User s Guide 1515 15 ...
Page 634: ...17 38 DS785UM1 Copyright 2007 Cirrus Logic IrDA EP93xx User s Guide 1717 17 ...
Page 648: ...19 6 DS785UM1 Copyright 2007 Cirrus Logic Watchdog Timer EP93xx User s Guide 1919 19 ...
Page 688: ...21 32 DS785UM1 Copyright 2007 Cirrus Logic I2S Controller EP93xx User s Guide 2121 21 ...
Page 790: ...27 20 DS785UM1 Copyright 2007 Cirrus Logic IDE Interface EP93xx User s Guide 2727 27 ...
Page 808: ...28 18 DS785UM1 Copyright 2007 Cirrus Logic GPIO Interface EP93xx User s Guide 2828 28 ...