Memory Interfaces
4-15
Memory Interface Traffic Controller
J
At reset, all requestors are initially in the low-priority queue and the
time-out registers are set to minimum value for each requestor. You
must program these registers before using dynamic priority.
J
The low-priority queue order is:
H
MPU
H
DSP
H
Local bus
H
DMA (all channels including LCD)
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.
4.3.2.2
EMIFS Operation
This interface generates the appropriate signal timings to drive the following
types of devices or compatible devices:
-
Intel fast boot block flash (23FxxxF3)
-
AMD simultaneous read/write boot sector flash (AM29DLxxxG)
-
AMD burst mode flash (AM29BLxxxC)
-
Intel StrataFlash memory (28FxxxJ3A)
-
Intel synchronous StrataFlash memory (28FxxxK3/K18)
-
Intel wireless flash memory (28FxxxW18)
-
Asynchronous SRAM
Every macroscopic flash command (read array, program, clear status register)
is sent to the flash memory controller by the MPU. The MPU writes in the flash,
followed by a read or a write, to set up the flash in the correct mode.
File/boot block flash basic operations supported are:
-
Asynchronous read, including specific reads like manufacturer ID
-
Burst read emulation (by multiple asynchronous reads) in 32-bit width
-
Reset or power down
-
Asynchronous write with WE in 16-bit width