SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
The GPMC_CONFIG3_i[3-0] ADVONTIME field (where i = 0 to 3) defines the nADV/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 nADV/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 nADV/ALE assertion. ADVRDOFFTIME and ADVWROFFTIME can be used to control an address and byte-enable valid hold time control after nADV/ALE deassertion. ADVRDOFFTIME and ADVWROFFTIME apply to synchronous and asynchronous modes.
The nADV/ALE signal transitions as controlled through ADVONTIME, ADVRDOFFTIME, and ADVWROFFTIME can be delayed by a half-GPMC_FCLK period by enabling the GPMC_CONFIG3_i[7] ADVEXTRADELAY bit. This half-GPMC_FCLK period provides more granularity on nADV/ALE assertion and deassertion time to ensure proper setup and hold time relative to GPMC output clock. The ADVEXTRADELAY configuration parameter is especially useful in configurations where GPMC output clock and GPMC_FCLK have the same frequency, but can be used for all GPMC configurations. If enabled, ADVEXTRADELAY applies to all parameters controlling nADV/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 nADV/ALE signal-deassertion time, including the extra half-GPMC_FCLK-period delay.
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. The user must ensure that ADVAADMUXxxOFFTIME is programmed to a value less than or equal to ADVxxOFFTIME. Functionality in AAD-multiplexed 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 nADV pulse is needed between the two AAD-multiplexed address phases, which is the typical case in synchronous mode. In this configuration, nADV is kept low until it reaches the correct ADVxxOFFTIME.
For more information about the use of ADVONTIME, ADVRDOFFTIME, ADVWROFFTIME, and ADVAADMUXRDOFFTIME and ADVAADMUXWROFFTIME for command latch enable (CLE) and address latch enable (ALE) use for a NAND flash interface, see Section 12.3.4.4.11, GPMC NAND Access Description.