SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
The GPMC_CONFIG4_i[19:16] WEONTIME bit field (where i = 0 to 7) defines the nWE signal-assertion time relative to start access time. The GPMC_CONFIG4_i[28:24] WEOFFTIME bit field defines the nWE signal-deassertion time relative to start access time. These bit fields apply only to write accesses. nWE is not asserted during a read cycle.
WEONTIME can be used to control an address and byte-enable valid setup time control before nWE assertion. WEOFFTIME can be used to control an address and byte-enable valid hold time control after nWE assertion.
nWE signal transitions as controlled through WEONTIME, and WEOFFTIME can be delayed by a half-GPMC_FCLK period by enabling the GPMC_CONFIG4_i[23] WEEXTRADELAY bit. This half-GPMC_FCLK period provides more granularity on nWE assertion and deassertion time to ensure proper setup and hold time relative to GPMC_CLK. If enabled, WEEXTRADELAY applies to all parameters controlling nWE transitions.
The WEEXTRADELAY bit must be used carefully to avoid control-signal overlap between successive accesses to different chip-selects. This implies the need to program the WRCYCLETIME bit field to be greater than the nWE signal-deassertion time, including the extra half-GPMC_FCLK-period delay.