10 Memory Interface
10 – 12
As shown in Figure 10.11, the ADSP-2101, ADSP-2111, ADSP-2105,
ADSP-2115, and ADSP-2161/62/63/64 processors have five external wait
state zones (DWAIT0–DWAIT4). Each of the five zones of external data
memory has its own programmable number of wait states. Wait states are
extra cycles that the processor either waits before latching data (on a read)
or drives the data (on a write). This means that one zone of memory could
be used for working with memory-mapped peripherals of one speed
while another zone was used with faster or slower peripherals. Similarly,
slower and faster memories can be used for different purposes, as long as
they are located in different zones of the data memory map.
As shown in Figures 10.12 and 10.13, the ADSP-2171, ADSP-21msp58/59,
and ADSP-2165/66 processors each have three wait state zones for
external data memory.
3BFF
3C00
37FF
3800
Data Memory
12K External
3FFF
0000
2FFF
3000
1K Reserved
Memory Mapped
Registers/Reserved
2K Internal
Data RAM
03FF
0400
07FF
0800
Wait States
DWAIT 2
(10K External)
3FFF
0000
2FFF
3000
No Wait States
DWAIT 0
(1K External)
DWAIT 1
(1K External)
Figure 10.12 Data Memory Map (ADSP-2171, ADSP-21msp58/59)