SPRUIU1C July 2020 – February 2024 DRA821U , DRA821U-Q1
The DIR pin is used to control I/O direction on the GPMC data bus GPMC_D[15-0]. Depending on pad multiplexing, this signal can be output and used externally to the device, if required. The DIR pin is low during transmit (OUT) and high during receive (IN).
For write accesses, the DIR pin stays OUT from start-cycle time to end-cycle time.
For read accesses, the DIR pin goes from OUT to IN at nOE assertion time and stays IN until:
Because of the bus-keeping feature of the GPMC, after a read or write access and with no other accesses pending, the default value of the DIR pin is OUT (see Section 12.3.4.4.8.10, Bus Keeping Support). In non-multiplexed devices, the DIR pin stays IN between two successive read accesses to prevent unnecessary toggling.