Memory Interfaces
4-13
Memory Interface Traffic Controller
J
The high-priority queue order is:
H
DMA transfer involving LCD channel
H
DSP
H
Local bus
H
DMA transfer involving channels other than LCD channel
-
Fixed priority is a special case of dynamic priority. To create a fixed priority,
all time-out registers must have a value of 0. This way any request made
goes into the high-priority queue after one clock cycle. Then the high-
priority queue provides a fixed priority.
4.3.1.2
IMIF Operation
The 192K bytes of internal SRAM are selected by an internal chip select based
on the appropriate address decode. The interface to the SRAM is 32 bits wide
and provides support for single and burst accesses. The SRAM operates at
the frequency of the traffic controller.
4.3.2
External Memory Interface Slow
The EMIFS interfaces with and handles all transactions to flash memory,
ROM, asynchronous memories, and synchronous burst flash. The interface
can drive up to four devices by assignment to one of four chip-selects. Each
chip-select has a corresponding register to specify the protocol used for the
associated external device.
Table 4–4 shows the EMIFS signal list.
Table 4–4. External Memory Interface Slow Signal List
Signal Name
I/O
Bus
Description
FLASH.RDY
I
–
Ready/busy signal from device
FLASH.WP
O
–
Write protection
FLASH.CLK
I/O
–
Clock signal for flash device
FLASH.RP
O
–
Flash power-down/reset
FLASH.CS0
O
–
Active-low chip-select for device
FLASH.CS1
O
–
Active-low chip-select for device
FLASH.CS2
†
O
–
Active-low chip-select for device
FLASH.CS3
O
–
Active-low chip-select for device
† FLASH.CS2 and FLASH.BAA are multiplexed on the same device pin. Pin function is selected using the OMAP5910 configu-
ration register, FUNC_MUX_CRTL_0. The FLASH.CS2 functionality is default.