6.7.3 GPMC
The general-purpose memory controller (GPMC) is a unified memory controller dedicated for interfacing with external memory devices like:
- Asynchronous SRAM-like memories and application-specific integrated circuit (ASIC) devices
- Asynchronous, synchronous, and page mode (available only in nonmultiplexed mode) burst NOR flash devices
- Pseudo-SRAM devices
The main features of the GPMC are:
- 8- or 16-bit-wide data path to external memory device
- Supports up to 4 chip select regions of programmable size and programmable base addresses in a total address space of 1 GB
- Fully pipelined operation for optimal memory bandwidth usage
- The clock to the external memory is provided from GPMC_FCLK 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_FCLK clock cycle.
- Flexible internal access time control (wait state) and flexible handshake mode using external WAIT pin monitoring
- Support bus keeping
- Support bus turnaround
- 32-bit TeraNet slave interface which supports non-wrapping and wrapping burst of up to 16 x 32 bits.
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-endian access only
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 nonmultiplexed NOR flash device
- External 16-bit address and data multiplexed NOR Flash device
- External 16-bit pseudo-SRAM (pSRAM) device
For more information, see section General-Purpose Memory Controller (GPMC) in chapter Memory Subsystem of the Device TRM.