GPMC
The GPMC_CONFIG2_i[12-8] CSRDOFFTIME (read access) and GPMC_CONFIG2_i[20-16]
CSWROFFTIME (write access) bit fields define the CSn signal deassertion time relative to start access
time.
CSONTIME, CSRDOFFTIME and CSWROFFTIME parameters are applicable to synchronous and
asynchronous modes. CSONTIME can be used to control an address and byte enable setup time before
chip-select assertion. CSRDOFFTIME and CSWROFFTIME can be used to control an address and byte
enable hold time after chip-select deassertion.
CSn signal transitions as controlled through CSONTIME, CSRDOFFTIME, and CSWROFFTIME can be
delayed by half a GPMC_FCLK period by enabling the GPMC_CONFIG2_i[7] CSEXTRADELAY bit. This
half of a GPMC_FCLK period provides more granularity on the CSn assertion and deassertion time to
guarantee proper setup and hold time relative to GPMC_CLK. CSEXTRADELAY is especially useful in
configurations where GPMC_CLK and GPMC_FCLK have the same frequency, but can be used for all
GPMC configurations. If enabled, CSEXTRADELAY applies to all parameters controlling CSn transitions.
The CSEXTRADELAY bit must be used carefully to avoid control-signal overlap between successive
accesses to different chip-selects. This implies the need to program the RDCYCLETIME and
WRCYCLETIME bit fields to be greater than the CSn signal-deassertion time, including the extra half-
GPMC_FCLK-period delay.
7.1.3.3.9.3 ADVn/ALE: Address Valid/Address Latch Enable Signal Control Assertion/Deassertion Time
(ADVONTIME / ADVRDOFFTIME / ADVWROFFTIME /
ADVEXTRADELAY/ADVAADMUXONTIME/ADVAADMUXRDOFFTIME/ADVAADMUXWROFFTIME
)
The GPMC_CONFIG3_i[3-0] ADVONTIME field defines the ADVn_ALE signal-assertion time relative to
start access time. It is common to read and write accesses.
The GPMC_CONFIG3_i[12-8] ADVRDOFFTIME (read access) and GPMC_CONFIG3_i[20-16]
ADVWROFFTIME (write access) bit fields define the ADVn_ALE signal-deassertion time relative to start
access time.
ADVONTIME can be used to control an address and byte enable valid setup time control before
ADVn_ALE assertion. ADVRDOFFTIME and ADVWROFFTIME can be used to control an address and
byte enable valid hold time control after ADVn_ALE de-assertion. ADVRDOFFTIME and
ADVWROFFTIME are applicable to both synchronous and asynchronous modes.
ADVn_ALE signal transitions as controlled through ADVONTIME, ADVRDOFFTIME, and
ADVWROFFTIME can be delayed by half a GPMC_FCLK period by enabling the GPMC_CONFIG3_i[7]
ADVEXTRADELAY bit. This half of a GPMC_FCLK period provides more granularity on ADVn_ALE
assertion and deassertion time to assure proper setup and hold time relative to GPMC_CLK. The
ADVEXTRADELAY configuration parameter is especially useful in configurations where GPMC_CLK and
GPMC_FCLK have the same frequency, but can be used for all GPMC configurations. If enabled,
ADVEXTRADELAY applies to all parameters controlling ADVn_ALE transitions.
ADVEXTRADELAY must be used carefully to avoid control-signal overlap between successive accesses
to different chip-selects. This implies the need to program the RDCYCLETIME and WRCYCLETIME bit
fields to be greater than ADVn_ALE signal-deassertion time, including the extra half-GPMC_FCLK-period
delay.
The GPMC_CONFIG3_i[6-4] ADVAADMUXONTIME, GPMC_CONFIG3_i[26-24]
ADVAADMUXRDOFFTIME, and GPMC_CONFIG3_i[30-28] ADVAADMUXWROFFTIME parameters have
the same functions as ADVONTIME, ADVRDOFFTIME, and ADVWROFFTIME, but apply to the first
address phase in the AAD-multiplexed protocol. It is the user responsibility to make sure
ADVAADMUXxxOFFTIME is programmed to a value lower than or equal to ADVxxOFFTIME. Functionality
in AAD-mux mode is undefined if the settings do not comply with this requirement.
ADVAADMUXxxOFFTIME can be programmed to the same value as ADVONTIME if no high ADVn pulse
is needed between the two AAD-mux address phases, which is the typical case in synchronous mode. In
this configuration, ADVn is kept low until it reaches the correct ADVxxOFFTIME.
See
for more details on ADVONTIME, ADVRDOFFTIME, ADVWROFFTIME, and
ADVAADMUXRDOFFTIME, ADVAADMUXWROFFTIME usage for CLE and ALE (Command / Address
Latch Enable) usage for a NAND Flash interface.
276
Memory Subsystem
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated