Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
563
DDR SDRAM Memory Controller—Intel
®
81341 and 81342
7.0
DDR SDRAM Memory Controller
This chapter describes the integrated Memory Controller Unit (DMCU), with operating
modes, initialization, external interfaces, and implementation details.
7.1
Overview
The Intel
®
81341 and 81342 I/O Processors (81341 and 81342) integrates a
high-performance, multi-ported Memory Controller to provide a direct interface
between the 81341 and 81342 and its local memory subsystem. The Memory Controller
supports:
• PC3200/PC4300 Double Data Rate II (DDR2 400 MHz and DDR2 533 MHz) SDRAM
• 512 Mbit and 1 Gbit and 2 Gbit DDR-II SDRAM technology support
• Registered and Unbuffered DDR2 DIMM support
• Dedicated port for Intel XScale
®
microarchitectures to DDR2 SDRAM
• Between 256 MBytes and 4 GBytes of 64-bit DDR2 SDRAM
• 36-bit addressable
• Two memory windows to address the same DDR SDRAM Memory
• Optimized core processor data processing 32-bit region
• Single-bit error correction, multi-bit detection support (ECC)
• 32-, 40- and 64-, 72-bit wide Memory Interfaces (non-ECC and ECC support)
DDR2 SDRAM interface provides a direct connection to a high bandwidth and reliable
memory subsystem. The DDR2 SDRAM interface consists of a 64-bit wide data path to
support up to 4.3 GBytes/s throughput. An 8-bit Error Correction Code (ECC) across
each 64-bit word improves system reliability. The ECC is stored in the DDR SDRAM
array along with data and checked when data is read. When code is incorrect, the
DMCU corrects data (when possible) before reaching the read initiator. User-defined
fault correction software is responsible for scrubbing the memory array. DMCU supports
two banks of DDR SDRAM made up of a two-bank dual-inline memory module (DIMM):
• DMCU has support for Registered and Unbuffered PC3200 and PC4300 DIMMs.
• The DMCU supports a 32-bit SDRAM data interface. This mode enables lower-cost
solutions at the cost of system performance.
• The DMCU responds to internal bus and core processor memory accesses within its
programmed address range and issues the memory request to the DDR SDRAM
interface.
• The DMCU contains transaction queues for each port enabling pipelining of
transactions to the DDR SDRAM for maximum performance.
• For 64-bit ECC memory, a 32-bit memory region programmable to operate as
32-bit ECC memory for higher core write performance by avoiding
Read-Modify-Write (RMW) operation of DDR SDRAM.
• The DMCU provides two chip enables to the memory subsystem. These two chip
enables service the DDR SDRAM subsystem (one per bank).