GPMC_FCLK
GPMC_CLK
gpmc_a[11:1]
gpmc_d[15:0]
nBE1nBE0
nCS
nADV
nWE
DIR
WAIT
Valid Address
Valid Address
D 0
D 1
D 2
D 3
D 4 D 5 D 6
D 7
D 7
OUT
CSONTIME
CSWROFFTIME
ADVONTIME
ADVWROFFTIME
WRDATAONADMUXBUS
WEONTIME
WEOFFTIME
CLKACTIVATIONTIME
WRACCESSTIME
PAGEBURSTACCESSTIME
PAGEBURSTACCESSTIME
PAGEBURSTACCESSTIME
WRCYCLETIME1
WRCYCLETIME0
gpmc-021
Public Version
www.ti.com
General-Purpose Memory Controller
Figure 10-21. Synchronous Multiple Write (Burst Write) in Address/Data-Multiplexed Mode
The first data of the burst is driven on the a/d bus at
[19:16] WRDATAONADMUXBUS.
10.1.5.11 pSRAM Basic Programming Model
pSRAM devices are SRAM-pin-compatible low-power memories that contain a self-refreshed DRAM
memory array. These devices can be accessed by the GPMC with the GPMC.
[11:10]
DEVICETYPE field (i = 0 to 7).
The pSRAM devices support the following operations:
•
Asynchronous single read
•
Asynchronous page read
•
Asynchronous single write
•
Synchronous single read and write
•
Synchronous burst read
•
Synchronous burst write
pSRAM devices must be powered up and initialized in a predefined manner according to the specifications
of the attached device.
pSRAM devices can be programmed to use either mode: fixed or variable latency. pSRAM devices can
either automatically schedule autorefresh operations, which force the GPMC to use its WAIT signal
capability when read or write operations occur during an internal self-refresh operation, or pSRAM devices
automatically include the autorefresh operation in the access time. These devices do not require additional
WAIT signal capability or a minimum nCS high pulse width between consecutive accesses to ensure that
the correct internal refresh operation is scheduled.
In both pSRAM cases, the GPMC configuration for this chip-select must be set according to the
specifications of the attached device.
2155
SWPU177N – December 2009 – Revised November 2010
Memory Subsystem
Copyright © 2009–2010, Texas Instruments Incorporated