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General-Purpose Memory Controller
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CAUTION
Although the GPMC interface can drive up to 8 chip-selects, the frequency
specified for this interface is for a specific load. If this load is exceeded, the
maximum frequency cannot be reached.
10.1.5.2 Access Protocol Configuration
10.1.5.2.1 Supported Devices
The access protocol of each chip-select can be independently specified through the
GPMC.
[11:10] DEVICETYPE parameter (where i =0 to 7) for:
•
Random-access synchronous or asynchronous memory like NOR flash, SRAM
•
NAND flash asynchronous devices
NOTE:
NAND flash interfacing requires the parameter settings of generic chip-select 0. For more
information about the NAND flash GPMC basic programming model and NAND support, see
, NAND Device Basic Programming Model, and
, NAND
Memory Device in Byte or Word 16 Stream Mode.
10.1.5.2.2 Access Size Adaptation and Device Width
Each chip-select can be independently configured through the GPMC.
DEVICESIZE field (i = 0 to 7) to interface with a 16-bit wide device or an 8-bit wide device. System
requests with data width greater than the external device data bus width are split into successive
accesses according to both the external device data-bus width and little-endian data organization.
NOTE:
The device does not provide the A0 byte address line required for random-byte addressable
8-bit wide device interfacing (for both multiplexed and nonmultiplexed protocol). It limits the
use of 8-bit wide device interfacing to byte-alias accesses. This limitation is not applicable to
NAND device interfacing (8-bit wide or 16-bit wide devices).
10.1.5.2.3 Address/Data-Multiplexing Interface
For random synchronous or asynchronous memory interfacing (DEVICETYPE = 0b00), an address- and
data-multiplexing protocol can be selected through the GPMC.
[9] MUXADDDATA bit (i
= 0 to 7). The nADV signal must be used as the external device address latch control signal. For the
associated chip-select configuration, nADV assertion and deassertion time and nOE assertion time must
be set to the appropriate value to meet the address latch setup/hold time requirements of the external
device. See
, GPMC Integration.
NOTE:
This address/data-multiplexing interface is not applicable to NAND device interfacing. NAND
devices require a specific address, command, and data multiplexing protocol. See
, NAND Device Basic Programming Model.
10.1.5.2.4 Address and Data Bus
See
, GPMC Address and Data Bus.
10.1.5.2.5 Asynchronous and Synchronous Access
For each chip-select configuration, the read access can be specified as either asynchronous or
synchronous access through the GPMC.
[29] READTYPE bit (i = 0 to 7). For each
chip-select configuration, the write access can be specified as either synchronous or asynchronous
access through the GPMC.
[27] WRITETYPE bit (i = 0 to 7).
2126
Memory Subsystem
SWPU177N – December 2009 – Revised November 2010
Copyright © 2009–2010, Texas Instruments Incorporated