SPRUIV7B May 2022 – September 2023 AM620-Q1 , AM623 , AM625 , AM625-Q1 , AM625SIP
NAND devices require correct command and address programming before data array read or write accesses. The GPMC does not include specific hardware to translate a random address system request into a NAND-specific multiphase access. In that sense, GPMC NAND support, as opposed to random memory-map device support, is data stream-oriented (byte or 16-bit word).
The GPMC NAND programming model depends on a software driver for address and command formatting with the correct data address pointer value according to the block and page structure. Because of NAND structure and protocol interface diversity, the GPMC does not support automatic command and address phase programming, and software drivers must access the NAND device ID to ensure that correct command and address formatting are used for the identified device.
NAND device data read and write accesses are achieved through an asynchronous read or write access. The associated chip-select signal timing control must be programmed according to the NAND device timing specification.
Any chip-select region can be qualified as a NAND region to constrain the nADV/ALE signal as ALE (ALE active high, default state value at low) during address program access, and the nBE0/CLE signal as CLE (CLE active high, default state value at low) during command program access. GPMC address lines are not used (the previous value is not changed) during NAND access.