Memory Interfaces For The Emifs - Texas Instruments OMAP5912 Reference Manual

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Memory Interfaces for the EMIFS

SPRU756A
Each chip-select (CS) controls an address range with dedicated configuration
registers to ensure compliance with the protocol and timing constraints of the
external device associated with it. Each chip-select configuration register
supports dynamic configuration.
The EMIFS can support 16-bit and 32-bit external device width. Based on the
CS configuration, the interface adjusts the access size (splitting word32)
according to the external device attached to the CS.
An 8-bit device width is not supported without adding external logic.
The EMIFS can control multiplexed address and data memory devices without
adding external logic based on CS configuration. The multiplexing scheme is
supported for synchronous and asynchronous access mode.
Both multiplexed and nonmultiplexed devices can be supported with the same
integrated circuit (IC) on different chip-selects (embedded IC non-multiplexed
memories and external multiplexed devices).
The EMIFS behavior conforms to the little-endian protocol. It supports 8-,16-,
or 32-bit asynchronous and synchronous read, 4- x 32-bit synchronous burst
read, and 8-, 16-, or 32-bit asynchronous write.
The EMIFS is a multimaster memory interface. It supports flexible and
programmable arbitration protocol (LRU priority ordering or dynamic
time-based priority ordering).
At boot time or at run time, CS0 and CS3 address mapping can be swapped.
The EMIFS includes a programmable time-out to prevent the system from
hanging with nonresponding devices. Automatic access completion with
interrupt and status logging are issued on time-out events.
The EMIFS supports dynamic local idle mode control. The EMIFS also
supports IC deep power-down mode request synchronization.
OMAP5912 can also support CompactFlash devices through the EMIFS.
There are a number of different memory types that can connect with the EMIFS
interface. These memory types will share the same pins on the device, but their
functionalities and controlling logic may differ.
The memory types and their associated controlling logic is:
-
Non-multiplexed NOR flash—controlled by EMIFS directly
-
Address/Data multiplexed NOR flash—controlled by EMIFS directly
-
8−bit NAND flash—controlled by either the EMIFS directly (software
NAND flash controller) or by the hardware NAND flash controller (NFC)
Memory Interfaces for the EMIFS
Memory Interfaces 19