6.6.2 GPMC
The General Purpose Memory Controller (GPMC) is an external memory controller of the device. Its data access engine provides a flexible programming model for communication with all standard memories.
The GPMC supports the following various access types:
- Asynchronous read/write access
- Asynchronous read page access (4, 8, and 16 Word16)
- Synchronous read/write access
- Synchronous read/write burst access without wrap capability (4, 8 and 16 Word16)
- Synchronous read/write burst access with wrap capability (4, 8 and 16 Word16)
- Address-data-multiplexed (AD) access
- Address-address-data (AAD) multiplexed access
- Little- and big-endian access
The GPMC can communicate with a wide range of external devices:
- External asynchronous or synchronous 8-bit wide memory or device (non burst device)
- External asynchronous or synchronous 16-bit wide memory or device
- External 16-bit non-multiplexed NOR flash device
- External 16-bit address and data multiplexed NOR Flash device
- External 8-bit and 16-bit NAND flash device
- External 16-bit pseudo-SRAM (pSRAM) device
The main features of the GPMC are:
- 8- or 16-bit-wide data path to external memory device
- Supports up to eight CS regions of programmable size and programmable base addresses in a total address space of 1 GiB
- Supports transactions controlled by a firewall
- On-the-fly error code detection using the Bose-ChaudhurI-Hocquenghem (BCH) (t = 4, 8, or 16) or Hamming code to improve the reliability of NAND with a minimum effect on software (NAND flash with 512-byte page size or greater)
- Fully pipelined operation for optimal memory bandwidth use
- The clock to the external memory is provided from GPMC functional clock divided by 1, 2, 3, or 4
- Supports programmable autoclock gating when no access is detected
- Independent and programmable control signal timing parameters for setup and hold time on a per-chip basis. Parameters are set according to the memory device timing parameters, with a timing granularity of one GPMC functional clock cycle.
- Flexible internal access time control (WAIT state) and flexible handshake mode using external WAIT pin monitoring
- Support bus keeping
- Support bus turnaround
- Prefetch and write posting engine associated with to achieve full performance from the NAND device with minimum effect on NOR/SRAM concurrent access
For more information, see section General-Purpose Memory Controller (GPMC) in chapter Memory Subsystem of the Device TRM.