GPMC
7.1.3.3
GPMC Functional Description
The GPMC basic programming model offers maximum flexibility to support various access protocols for
each of the eight configurable chip-selects. Use optimal chip-select settings, based on the characteristics
of the external device:
•
Different protocols can be selected to support generic asynchronous or synchronous random-access
devices (NOR flash, SRAM) or to support specific NAND devices.
•
The address and the data bus can be multiplexed on the same external bus.
•
Read and write access can be independently defined as asynchronous or synchronous.
•
System requests (byte, 16-bit word, burst) are performed through single or multiple accesses. External
access profiles (single, multiple with optimized burst length, native- or emulated-wrap) are based on
external device characteristics (supported protocol, bus width, data buffer size, native-wrap support).
•
System burst read or write requests are synchronous-burst (multiple-read or multiple-write). When
neither burst nor page mode is supported by external memory or ASIC devices, system burst read or
write requests are translated to successive single synchronous or asynchronous accesses (single
reads or single writes). 8-bit wide devices are supported only in single synchronous or single
asynchronous read or write mode.
•
To simulate a programmable internal-wait state, an external wait pin can be monitored to dynamically
control external access at the beginning (initial access time) of and during a burst access.
Each control signal is controlled independently for each chip-select. The internal functional clock of the
GPMC (GPMC_FCLK) is used as a time reference to specify the following:
•
Read- and write-access duration
•
Most GPMC external interface control-signal assertion and deassertion times
•
Data-capture time during read access
•
External wait-pin monitoring time
•
Duration of idle time between accesses, when required
260
Memory Subsystem
SPRUH73H – October 2011 – Revised April 2013
Copyright © 2011–2013, Texas Instruments Incorporated