SPRUI30H November 2015 – May 2024 DRA745 , DRA746 , DRA750 , DRA756
When wait pin monitoring is enabled for read accesses (WAITREADMONITORING), the effective access time is a logical AND combination of the RDACCESSTIME timing completion and the wait-deasserted state.
During asynchronous read accesses with wait pin monitoring enabled, the wait pin must be at a valid level (asserted or deasserted) for at least two GPMC clock cycles before RDACCESSTIME completes, to ensure correct dynamic access-time control through wait pin monitoring. The advance pipelining of the two GPMC clock cycles is the result of the internal synchronization requirements for the WAIT signal.
In this context, RDACCESSTIME is used as a wait invalid timing window and is set to such a value that the wait pin is at a valid state two GPMC clock cycles before RDACCESSTIME completes.
Similarly, during a multiple-access cycle (for example, asynchronous read page mode), the effective access time is a logical AND combination of PAGEBURSTACCESSTIME timing completion and the wait-deasserted state. Wait monitoring pipelining is also applicable to multiple accesses (access within a page).
When a delay larger than two GPMC clocks must be observed between wait-pin deactivation time and data valid time (including the required GPMC and the device data setup time), an extra delay can be added between wait-pin deassertion time detection and effective data-capture time and the effective unlock of the CYCLETIME counter. This extra delay can be programmed in the GPMC_CONFIG1_i[19:18] WAITMONITORINGTIME bit field (where i = 0 to 7).
Figure 15-60 shows wait behavior during an asynchronous single read access.
The WAIT signal is active low. GPMC_CONFIG1_i[19:18] WAITMONITORINGTIME = 0b00, or 0b01.