Freescale Semiconductor MPC8313E PowerQUICC II Pro Family Reference Manual page 93

1.2.5.1 PCI Bus Arbitration Unit
The PCI controller contains a PCI bus arbitration unit, which eliminates the need for an external unit, thus
lowering system complexity and cost. It has the following features:
• Supports three REQ/GNT signal pairs, thus supporting three external masters. The device PCI
controller is the fourth member of the arbitration pool.
• The bus arbitration unit allows fairness as well as a priority mechanism.
• A two-level round-robin scheme is used in which each device can be programmed within a pool of
a high- or low-priority arbitration. One member of the low-priority pool is promoted to the
high-priority pool. As soon as it is granted the bus, it returns to the low-priority pool.
• The unit can be disabled to allow a remote arbitration unit to be used.
• The unit can be isolated to allow power shut off of external devices.
1.2.6 Universal Serial Bus (USB) 2.0
The USB 2.0 controller offers operation as a host or device. The USB controller provides point-to-point
connectivity, which complies with the Universal Serial Bus Revision 2.0 Specification. The USB controller
can be configured to operate as a stand-alone host or stand-alone device. See
information.
The host and device functions are both configured to support the following four types of USB transfers:
• Bulk
• Control
• Interrupt
• Isochronous
MPC8313E PowerQUICC™ II Pro Integrated Processor Family Reference Manual, Rev. 2
Freescale Semiconductor
Dual-Role
Module
(DR)
DR Mux
Figure 1-4. USB Controllers Port Configuration
CSB
TX Buffer
RX Buffer
On-Chip PHY
Overview
Figure 1-4 for more
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