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1.1 Purpose of the Peripheral
1-2
KeyStone Architecture External Memory Interface (EMIF16) User Guide
SPRUGZ3A—May 2011
Chapter 1—Introduction
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1.1 Purpose of the Peripheral
The EMIF16 module is intended to provide a glue-less interface to a variety of
asynchronous memory devices like ASRAM, NOR and NAND memory. A total of
256M bytes of any of these memories can be accessed at any given time via four chip
selects with 64M byte access per chip select. NOR Flash can be used for boot purposes.
These memories can also be used for Data Logging purposes.
Synchronous memories such as DDR1 SDRAM, SDR SDRAM and Mobile SDR are not
supported. Refer to the data manual for a particular KeyStone part for information on
the number of instances of this peripheral supported.
1.2 Features
The EMIF16 module supports the following features:
•
Up to 256MB asynchronous address range over 4 chip selects
•
8-bit and 16-bit data widths
•
Programmable cycle timings for each chip select
•
Extended wait support (if available model supports)
•
Select Strobe mode support (if available model supports)
•
Page/Burst mode read support for NOR Flash
•
1-bit ECC for 8-bit and 16-bit NAND Flash (Does not support error correction)
•
4-bit ECC for 8-bit and 16-bit NAND Flash (Does not support error correction)
•
Big and little endian operation
The EMIF16 module does not support the following features:
•
Synchronous devices such as SDR DRAM, DDR1 SDRAM and Mobile SDR
•
32-bit mode operation
•
OneNAND and PCMCIA interfaces
•
NAND Flash that requires chip select to stay low during
t
R
time for reads
Note—
The 64MB limit per chip select applies only for asynchronous memories
that use the EMIF16 address bus for addressing - typically ASRAM and NOR
flash. NAND flash uses the data bus as a multiplexed data/address bus and does
not use EMIF16 address pins for addressing (Only CLE and ALE signals use
the address bus. Refer to Section 3.1 ‘‘
’’ for more details).
So NAND Flash > 64MB can be supported on one chip select.