ADSP-2185
Table II.
PMOVLAY Memory
0
1
Internal
External
Overlay 1
External
Overlay 2
A13
A12:0
2
Not Applicable Not Applicable
0
13 LSBs of Address
Between 0x2000
and 0x3FFF
1
13 LSBs of Address
Between 0x2000
and 0x3FFF
There are 16,352 words of memory accessible internally when
the DMOVLAY register is set to 0. When DMOVLAY is set to
something other than 0, external accesses occur at addresses
0x0000 through 0x1FFF. The external address is generated as
shown in Table III.
Table III.
DMOVLAY Memory
0
1
Internal
External
Overlay 1
External
Overlay 2
A13
A12:0
This organization provides for two external 8K overlay segments
using only the normal 14 address bits. This allows for simple
program overlays using one of the two external segments in
place of the on-chip memory. Care must be taken in using this
overlay space in that the processor core (i.e., the sequencer)
does not take into account the PMOVLAY register value. For
example, if a loop operation was occurring on one of the exter-
nal overlays and the program changes to another external over-
lay or internal memory, an incorrect loop operation could occur.
In addition, care must be taken in interrupt service routines as
the overlay registers are not automatically saved and restored on
the processor mode stack.
When Mode B = 1, booting is disabled and overlay memory is
disabled (PMOVLAY must be 0). Figure 5 shows the memory
map in this configuration.
PROGRAM MEMORY
ADDRESS
0x3FFF
2
Not Applicable Not Applicable
13 LSBs of Address
0
Between 0x2000
and 0x3FFF
13 LSBs of Address
1
Between 0x2000
and 0x3FFF
This organization allows for two external 8K overlays using only
the normal 14 address bits. All internal accesses complete in one
cycle. Accesses to external memory are timed using the wait
states specified by the DWAIT register.
I/O Space (Full Memory Mode)
INTERNAL 8K
(PMOVLAY = 0,
MODE B = 1)
0x2000
0x1FFF
The ADSP-2185 supports an additional external memory space
called I/O space. This space is designed to support simple con-
nections to peripherals or to bus interface ASIC data registers.
I/O space supports 2048 locations. The lower eleven bits of the
external address bus are used; the upper three bits are unde-
fined. Two instructions were added to the core ADSP-2100
Family instruction set to read from and write to I/O memory
space. The I/O space also has four dedicated 3-bit wait state
registers, IOWAIT0-3, which specify up to seven wait states to
be automatically generated for each of four regions. The wait
states act on address ranges as shown in Table IV.
Table IV.
8K EXTERNAL
0x0000
Address Range
Figure 5. Program Memory (Mode B = 1)
Data Memory
Wait State Register
IOWAIT0
IOWAIT1
IOWAIT2
IOWAIT3
The ADSP-2185 has 16,352 16-bit words of internal data
memory. In addition, the ADSP-2185 allows the use of 8K
external memory overlays. Figure 6 shows the organization of
the data memory.
DATA MEMORY
32 MEMORY–
MAPPED REGISTERS
ADDRESS
0x3FFF
0x3FEO
0x3FDF
INTERNAL
8160 WORDS
0x2000
8K INTERNAL
(DMOVLAY = 0)
OR
EXTERNAL 8K
(DMOVLAY = 1, 2)
0x1FFF
0x000–0x1FF
0x200–0x3FF
0x400–0x5FF
0x600–0x7FF
Composite Memory Select (CMS)
The ADSP-2185 has a programmable memory select signal that
is useful for generating memory select signals for memories
mapped to more than one space. The
CMS
signal is generated
to have the same timing as each of the individual memory select
signals (PMS,
DMS, BMS, IOMS),
but can combine their
functionality.
When set, each bit in the CMSSEL register causes the
CMS
signal to be asserted when the selected memory select is as-
serted. For example, to use a 32K word memory to act as both
program and data memory, set the
PMS
and
DMS
bits in the
CMSSEL register and use the
CMS
pin to drive the chip select
of the memory and use either
DMS
or
PMS
as the additional
address bit.
The
CMS
pin functions as the other memory select signals, with
the same timing and bus request logic. A 1 in the enable bit
causes the assertion of the
CMS
signal at the same time as the
–8–
REV. 0
0x0000
Figure 6. Data Memory
AD [ ANALOG DEVICES ]
