3 host controller driver responsibilities, 1 host controller management, 2 bandwidth allocation – Cirrus Logic EP93xx User Manual
Page 446: 3 host controller driver responsibilities -6, Figure 11-5. sample interrupt endpoint schedule -6
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DS785UM1
Copyright 2007 Cirrus Logic
Universal Serial Bus Host Controller
EP93xx User’s Guide
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Figure 11-5. Sample Interrupt Endpoint Schedule
11.2.3 Host Controller Driver Responsibilities
This section summarizes the Host Controller Driver (HCD) responsibilities.
11.2.3.1 Host Controller Management
The Host Controller Driver manages the operation of the Host Controller (HC). It does so by
communicating directly to the operational registers in the Host Controller and establishing the
interrupt Endpoint Descriptor list head pointers in the HCCA.
The Host Controller Driver maintains the state of the HC, list processing pointers, list
processing enables, and interrupt enables.
11.2.3.2 Bandwidth Allocation
All access to the USB is scheduled by the Host Controller Driver. The Host Controller Driver
allocates a portion of the available bandwidth to each periodic endpoint. If sufficient
bandwidth is not available, a newly-connected periodic endpoint will be denied access to the
bus.
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Interrupt
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Interrupt Endpoint Descriptors
Endpoint Poll Interval (ms)