Memory Interfaces
4-16
The following operations are also supported for burst flash devices:
-
Synchronous burst read mode (for Intel and AMD flashes)
An additional read mode is provided that supports burst read on page mode
ROM devices.
Figure 4–3 through Figure 4–7 show the external timing of the protocols used
by the EMIF slow interface.
4.3.2.3
Device Initialization
Depending on the flash memory or RAM device associated with each chip-
select, the EMIFS interface must be initialized. If the device used is a flash, the
flash may have to be initialized in the correct protocol to achieve maximum
performance.
To use the external flash device with the synchronous flash burst protocol, the
following configuration must be set in the flash device and in the EMIFS chip-
select configuration registers (see Table 4–13, EMIF Slow Chip-Select
Configuration Registers):
-
Read mode
-
Frequency configuration
-
Data output configuration
-
Burst order. The EMIF only supports linear burst order.
-
Burst length
-
CLK configuration
-
Flash mode operation. Some flash modules use multiple signals for
burst operations (see Section 4.3.2.7, Burst Read Operation, for more
information).
After reset, each of the EMIF slow chip-select configuration registers is config-
ured in asynchronous mode, with 15 wait cycles and a clock divider of 6 (rela-
tive to the traffic controller clock). This configuration ensures maximum
compatibility with many existing devices.