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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Reference Number: 306262-004US
53
Functional Overview—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
• 32-bit, 0-66MHz PCI bus operation
• Provides initiator (master) and target (slave) PCI interfaces
• Provides AHB-to-PCI and PCI-to-AHB DMA channels
• Includes PCI bus arbiter supporting up to 4 external PCI masters using round-robin
arbitration.
• Access to PCI Configuration registers from PCI and AHB busses
• Provides interrupt to processor to indicate transaction errors on the PCI or AHB bus
• Provides interrupt to processor for DMA complete and DMA error
• Provides doorbell interrupt generation capability to PCI and AHB agents
• Byte, half word, word single reads/writes, burst word reads/writes supported on
AHB and busses
• Generates memory, I/O, and configuration cycles as PCI master
• Provides AHB masters with full access to the 4Gbyte PCI address space
• Provides PCI-to-AHB address translation to map PCI accesses to AHB address space
2.1.7
DDRI SDRAM Controller
The IXP45X/IXP46X network processors integrate a high-performance, multi-ported
Memory Controller Unit (MCU) to provide a direct interface between the IXP45X/IXP46X
network processors and their local memory subsystem. The MCU supports:
• DDRI 266 SDRAM
• 128/256/512-Mbit, 1-Gbit DDRI SDRAM technology support
• Only unbuffered DRAM support (No registered DRAM support)
• Dedicated port for Intel XScale
®
Processor to DDRI SDRAM
• 32 Mbyte 32-bit DDRI SDRAM for low-cost solutions
• Up to 1 Gbyte of 32-bit DDRI SDRAM for large memory requirements
• Single-bit error correction, multi-bit detection support (ECC)
• 32, 40-bit wide Memory Interfaces (non-ECC and ECC support)
The DDRI SDRAM interface provides a direct connection to a high bandwidth and
reliable memory subsystem. The DDRI SDRAM interface consists of a 32-bit-wide data
path to support up to 1.0 GBps throughput.
An 8-bit Error Correction Code (ECC) across each 32-bit word improves system
reliability. It is important to note that ECC is also referred to as CB in many DIMM
specs. The pins used for ECC on the IXP45X/IXP46X network processors are called
DDRI_CB[7:0]. The controller supports the 8 bits due to the fact that internally it is a
32 or 64 bit controller. However, this implementation of the controller only supports 32
bits. The ECC circuitry was designed to operate always on a 64 bit word and when
operating in 32 bit mode, the upper 32 bits are driven to zeros internally.
Note:
The Intel
®
IXP455 Network Processor does not support ECC functionality. For details,
see the Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Datasheet.
The MCU supports two banks of DDRI SDRAM. The MCU has support for unbuffered
DDRI 266 only.