at91sam9g20-cu ATMEL Corporation, at91sam9g20-cu Datasheet - Page 707

• Manufacturer Part Number: at91sam9g20-cu
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

38. USB Host Port (UHP)
38.1
38.2
Figure 38-1. Block Diagram
6384B–ATARM–15-Dec-08
AHB
AHB
uhp_int
UHPCK
MCK
Master
Overview
Block Diagram
Slave
Master Block
Slave Block
Registers
OHCI
HCI
HCI
The USB Host Port (UHP) interfaces the USB with the host application. It handles Open HCI
protocol (Open Host Controller Interface) as well as USB v2.0 Full-speed and Low-speed
protocols.
The USB Host Port integrates a root hub and transceivers on downstream ports. It provides sev-
eral high-speed half-duplex serial communication ports at a baud rate of 12 Mbit/s. Up to 127
USB devices (printer, camera, mouse, keyboard, disk, etc.) and the USB hub can be connected
to the USB host in the USB “tiered star” topology.
The USB Host Port controller is fully compliant with the Open HCI specification. The USB Host
Port User Interface (registers description) can be found in the Open HCI Rev 1.0 Specification
available on http://h18000.www1.hp.com/productinfo/development/openhci.html. The standard
OHCI USB stack driver can be easily ported to Atmel’s architecture in the same way all existing
class drivers run without hardware specialization.
This means that all standard class devices are automatically detected and available to the user
application. As an example, integrating an HID (Human Interface Device) class driver provides a
plug & play feature for all USB keyboards and mouses.
Access to the USB host operational registers is achieved through the AHB bus slave interface.
The Open HCI host controller initializes master DMA transfers through the ASB bus master inter-
face as follows:
Control
• Fetches endpoint descriptors and transfer descriptors
• Access to endpoint data from system memory
Data
List Processor
FIFO 64 x 8
Regsisters
ED & TD
Block
Root Hub
Host SIE
and
AT91SAM9G20 Preliminary
Hub Registers
PORT S/M
PORT S/M
OHCI Root
v2.0 Full-speed Transceiver
USB transceiver
USB transceiver
Embedded USB
DM
DM
DP
DP
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