Texas Instruments AM335 Series Technical Reference Manual

DATA 0 ADD 1
nOE
nCS0
DIR IN OUT
A[16:1]/D[15:0]
OEOFFTIME
BUSTURNAROUND
CSOFFTIME
RDCYCLETIME
RD/WRCYCLETIME
New read/write
access
GPMC www.ti.com
Figure 7-11. Read to Read / Write for a Address-Data or AAD-Multiplexed Device, On Same CS,
With Bus Turnaround
7.1.3.3.8.3.7.2 Idle Cycles Between Accesses to Same Chip-Select (CYCLE2CYCLESAMECSEN,
CYCLE2CYCLEDELAY)
Some devices require a minimum chip-select signal inactive time between accesses. The
GPMC_CONFIG6_i[7] CYCLE2CYCLESAMECSEN bit enables insertion of a minimum number of
GPMC_FCLK cycles, defined by the GPMC_CONFIG6_i[11-8] CYCLE2CYCLEDELAY field, between
successive accesses of any type (read or write) to the same chip-select.
If CYCLE2CYCLESAMECSEN is enabled, any subsequent access to the same chip-select is delayed until
its CYCLE2CYCLEDELAY completes. The CYCLE2CYCLEDELAY counter starts when
CSRDOFFTIME/CSWROFFTIME completes.
The same applies to successive accesses occurring during 32-bit word or burst accesses split into
successive single accesses when the single-access mode is used (GPMC_CONFIG1_i[30]
READMULTIPLE = 0 or GPMC_CONFIG1_i[28] WRITEMULTIPLE = 0).
All control signals are kept in their default states during these idle GPMC_FCLK cycles. This prevents
back-to-back accesses to the same chip-select without idle cycles between accesses.
7.1.3.3.8.3.7.3 Idle Cycles Between Accesses to Different Chip-Select (CYCLE2CYCLEDIFFCSEN,
CYCLE2CYCLEDELAY)
Because of the pipelined behavior of the system, successive accesses to different chip-selects can occur
back-to-back with no idle cycles between accesses. Depending on the control signals (CSn, ADV_ALEn,
BE0_CLEn, OE_REn, WEn) assertion and de-assertion timing parameters and on the IC timing
parameters, some control signals assertion times may overlap between the successive accesses to
different CS. Similarly, some control signals (WEn, OE_REn) may not respect required transition times.
To work around the overlapping and to observe the required control-signal transitions, a minimum of
CYCLE2CYCLEDELAY inactive cycles is inserted between the access being initiated to this chip-select
and the previous access ending for a different chip-select. This applies to any type of access (read or
write).
272
Memory Subsystem SPRUH73H–October 2011–Revised April 2013
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Texas Instruments AM335 Series Specifications

General

Brand	Texas Instruments
Model	AM335 Series
Category	Computer Hardware
Language	English