Data Transfer
3-88
ADSP-214xx SHARC Processor Hardware Reference
Bursts are not divisible. During reads, all DDR2 data are received
and on-chip masked by the DDR2 controller. For single write
access in SISD mode, the 3rd and 4th data needs to be masked.
The data masking (
DDR2_DM1-0
signal) is only performed during
write operations as shown in
SIMD write access to the DDR2 memory should be even address
aligned. If odd address aligned, the throughput is reduced by a fac-
tor of 2. This does not apply to SIMD reads or any SISD mode.
For more information on SIMD access, see the
SHARC Processor
Programming Reference
.
External Instruction Fetch
The processors support direct fetch of instructions from external memory,
using the 16-bit external port. Fetching is supported from external mem-
ory bank 0 space which is selected by
MS0
. This external memory can
either be SDRAM, or asynchronous memory, such as SRAM or flash.
While 16-bit to 48-bit packing is supported when the external
memory is SDRAM, the external asynchronous memory interface
(AMI) also supports 8/16-bit to 48-bit instruction packing.
Interrupt Vector Table (IVT)
The interrupt vector table can be located in the internal ROM (0x80 000,
IIVT
bit = 0) or internal RAM (0x8C 000,
IIVT
bit = 1) based on the
Table 3-18. DDR2 SISD Access
Access
Logical x32
Physical x16
Comment
Explicit only
DM(0x200000) = R0;
DM(0x400000) = R0;(LSW)
DM(0x400001) = R0;(MSW)
DM(0x400002) = S0;(LSW)
DM(0x400003) = S0;(MSW)
DDR2_DM1–0 = low
DDR2_DM1–0 = low
DDR2_DM1–0 = high
DDR2_DM1–0 = high
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Содержание SHARC ADSP-214 Series
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Страница 616: ...Debug Features 14 22 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
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Страница 1132: ...Register Listing A 306 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...
Страница 1192: ...Index I 34 ADSP 214xx SHARC Processor Hardware Reference www BDTIC com ADI...