ADSP-2186BSTZ-160 Datasheet, PDF (8/36 Pages) Analog Devices – DSP Microcomputer

ADSP-2186
The master reset sets all internal stack pointers to the empty
stack condition, masks all interrupts and clears the MSTAT
register. When RESET is released, if there is no pending bus
request and the chip is configured for booting, the boot-loading
sequence is performed. The first instruction is fetched from
on-chip program memory location 0x0000 once boot loading
completes.
MEMORY ARCHITECTURE
The ADSP-2186 provides a variety of memory and peripheral
interface options. The key functional groups are Program Memory,
Data Memory, Byte Memory and I/O.
Program Memory (Full Memory Mode) is a 24-bit-wide space
for storing both instruction opcodes and data. The ADSP-2186
has 8K words of Program Memory RAM on chip, and the capabil-
ity of accessing up to two 8K external memory overlay spaces using
the external data bus. Both an instruction opcode and a data value
can be read from on-chip program memory in a single cycle.
Data Memory (Full Memory Mode) is a 16-bit-wide space
used for the storage of data variables and for memory-mapped
control registers. The ADSP-2186 has 8K words on Data
Memory RAM on chip, consisting of 8160 user-accessible
locations and 32 memory-mapped registers. Support also exists
for up to two 8K external memory overlay spaces through the
external data bus.
Byte Memory (Full Memory Mode) provides access to an
8-bit wide memory space through the Byte DMA (BDMA) port.
The Byte Memory interface provides access to 4 MBytes of
memory by utilizing eight data lines as additional address lines.
This gives the BDMA Port an effective 22-bit address range. On
power-up, the DSP can automatically load bootstrap code from
byte memory.
I/O Space (Full Memory Mode) allows access to 2048 loca-
tions of 16-bit-wide data. It is intended to be used to communi-
cate with parallel peripheral devices such as data converters and
external registers or latches.
Program Memory
The ADSP-2186 contains an 8K × 24 on-chip program RAM.
The on-chip program memory is designed to allow up to two
accesses each cycle so that all operations can complete in a
single cycle. In addition, the ADSP-2186 allows the use of 8K
external memory overlays.
The program memory space organization is controlled by the
Mode B pin and the PMOVLAY register. Normally, the ADSP-
2186 is configured with Mode B = 0 and program memory
organized as shown in Figure 4.
PROGRAM MEMORY
EXTERNAL 8K
(PMOVLAY = 1 or 2,
MODE B = 0)
ADDRESS
0x3FFF
0x2000
0x1FFF
8K INTERNAL
0x0000
Figure 4. Program Memory (Mode B = 0)
There are 8K words of memory accessible internally when the
PMOVLAY register is set to 0. When PMOVLAY is set to some-
thing other than 0, external accesses occur at addresses 0x2000
through 0x3FFF. The external address is generated as shown in
Table II.
Table II. PMOVLAY Addressing
PMOVLAY Memory A13
A12:0
0
Reserved Not Applicable Not Applicable
1
External
Overlay 1 0
13 LSBs of Address
Between 0x2000
and 0x3FFF
2
External
Overlay 2 1
13 LSBs of Address
Between 0x2000
and 0x3FFF
NOTE: Addresses 0x2000 through 0x3FFF should not be accessed when
PMOVLAY = 0.
This organization provides for two external 8K overlay segments
using only the normal 14 address bits, which 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 is occurring on one of the external
overlays and the program changes to another external overlay 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
RESERVED
ADDRESS
0x3FFF
8K EXTERNAL
0x2000
0x1FFF
0x0000
Figure 5. Program Memory (Mode B = 1)
Data Memory
The ADSP-2186 has 8160 16-bit words of internal data memory.
In addition, the ADSP-2186 allows the use of 8K external memory
overlays. Figure 6 shows the organization of the data memory.
DATA MEMORY
32 MEMORY–
MAPPED REGISTERS
INTERNAL
8160 WORDS
ADDRESS
0x3FFF
0x3FEO
0x3FDF
0x2000
0x1FFF
EXTERNAL 8K
(DMOVLAY = 1, 2)
0x0000
Figure 6. Data Memory
–8–
REV. B