![Freescale Semiconductor MCF54455 Скачать руководство пользователя страница 254](http://html1.mh-extra.com/html/freescale-semiconductor/mcf54455/mcf54455_reference-manual_2330541254.webp)
Universal Serial Bus Interface – On-The-Go Module
Freescale Semiconductor
10-47
10.4
Functional Description
This module can be broken down into functional sub-blocks as described below.
10.4.1
System Interface
The system interface block contains all the control and status registers to allow a core to interface to the
module. These registers allow the processor to control the configuration and ascertain the capabilities of
the module and, they control the module’s operation.
10.4.2
DMA Engine
The USB module contains a local DMA engine. It is responsible for moving all of the data transferred over
the USB between the module and system memory. Like the system interface block, the DMA engine block
uses a simple synchronous bus signaling protocol.
The DMA controllers must access control information and packet data from system memory. Control
information is contained in link list based queue structures. The DMA controllers have state machines able
to parse data structures defined in the EHCI specification. In host mode, the data structures are EHCI
compliant and represent queues of transfers performed by the host controller, including the
split-transaction requests that allow an EHCI controller to direct packets to FS and LS speed devices. In
device mode, data structures are similar to those in the EHCI specification and used to allow device
responses to be queued for each of the active pipes in the device.
10.4.3
FIFO RAM Controller
The FIFO RAM controller is used for context information and to control FIFOs between the protocol
engine and the DMA controller. These FIFOs decouple the system processor/memory bus requests from
the extremely tight timing required by USB.
The use of the FIFO buffers differs between host and device mode operation. In host mode, a single data
channel maintains in each direction through the buffer memory. In device mode, multiple FIFO channels
maintain for each of the active endpoints in the system.
In host mode, the USB OTG modules use 16-byte transmit buffers and 16-byte receive buffers. For the
USB OTG module, device operation uses a single 16-byte receive buffer and a 16-byte transmit buffer for
each endpoint.
10.4.4
Physical Layer (PHY) Interface
Readers should familiarize themselves with chapter 7 of the
Universal Serial Bus Specification, Revision
2.0.
The USB OTG modules contain an on-chip digital to analog transceiver (XCVR) for DP and DN USB
network communication. The USB module defaults to FS XCVR operation and can communicate in LS.
The USB OTG module may interface to any ULPI compatible PHY as well.
Due to pin-count limitations the USB module only supports certain combinations of PHY interfaces and
USB functionality. Refer to the
for more information.
Содержание MCF54455
Страница 33: ...xxviii Freescale Semiconductor ...
Страница 67: ...Freescale Semiconductor 1 ...
Страница 125: ...Freescale Semiconductor 1 ...
Страница 145: ...Enhanced Multiply Accumulate Unit EMAC 5 21 Freescale Semiconductor ...
Страница 173: ...Cache 6 28 Freescale Semiconductor ...
Страница 179: ...Static RAM SRAM 7 6 Freescale Semiconductor ...
Страница 207: ...Power Management 9 16 Freescale Semiconductor ...
Страница 323: ...Reset Controller Module 13 8 Freescale Semiconductor ...
Страница 389: ...Pin Multiplexing and Control 16 44 Freescale Semiconductor ...
Страница 575: ...PCI Bus Controller 22 58 Freescale Semiconductor ...
Страница 600: ...Advanced Technology Attachment ATA Freescale Semiconductor 23 25 ...
Страница 601: ...Freescale Semiconductor 1 ...
Страница 842: ...I2 C Interface Freescale Semiconductor 33 16 ...
Страница 843: ...Freescale Semiconductor 1 ...
Страница 921: ...Revision History A 6 Freescale Semiconductor ...