ADSP-2184L Просмотр технического описания (PDF) - Analog Devices
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ADSP-2184L Datasheet PDF : 48 Pages
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ADSP-2184L/ADSP-2185L/ADSP-2186L/ADSP-2187L
1M⍀
CLKIN
XTAL
DSP
CLKOUT
Figure 3. External Crystal Connections
RESET
The RESET signal initiates a master reset of the ADSP-218xL.
The RESET signal must be asserted during the power-up
sequence to assure proper initialization. RESET during initial
power-up must be held long enough to allow the internal clock
to stabilize. If RESET is activated any time after power-up, the
clock continues to run and does not require stabilization time.
The power-up sequence is defined as the total time required for
the crystal oscillator circuit to stabilize after a valid VDD is
applied to the processor, and for the internal phase-locked loop
(PLL) to lock onto the specific crystal frequency. A minimum of
2000 CLKIN cycles ensures that the PLL has locked, but does
not include the crystal oscillator start-up time. During this
power-up sequence, the RESET signal should be held low. On
any subsequent resets, the RESET signal must meet the mini-
mum pulse width specification (tRSP).
The RESET input contains some hysteresis; however, if an RC
circuit is used to generate the RESET signal, the use of an exter-
nal Schmitt trigger is recommended.
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-218xL series provides a variety of memory and
peripheral interface options. The key functional groups are Pro-
gram Memory, Data Memory, Byte Memory, and I/O. Refer to
Figure 4 through Figure 7 for PM and DM memory allocations
in the ADSP-218xL series.
Program Memory
Program Memory (Full Memory Mode) is a 24-bit-wide space
for storing both instruction opcodes and data. The member
DSPs of this series have up to 32K words of Program Memory
RAM on chip, and the capability of accessing up to two 8K
external memory overlay spaces, using the external data bus.
Program Memory (Host Mode) allows access to all internal
memory. External overlay access is limited by a single external
address line (A0). External program execution is not available in
Host Mode due to a restricted data bus that is only 16 bits wide.
Data Memory
Data Memory (Full Memory Mode) is a 16-bit-wide space used
for the storage of data variables and for memory-mapped con-
trol registers. The ADSP-218xL series has up to 32K words of
Data Memory RAM on-chip. Part of this space is used by 32
memory-mapped registers. Support also exists for up to two 8K
external memory overlay spaces through the external data bus.
All internal accesses complete in one cycle. Accesses to external
memory are timed using the wait states specified by the DWAIT
register.
Data Memory (Host Mode) allows access to all internal mem-
ory. External overlay access is limited by a single external
address line (A0).
0x3FFF
PROGRAM MEMORY
MODEB = 1
RESERVED
0x2000
0x1FFF
0x0000
EXTERNAL PM
0x3FFF
0x2000
0x1FFF
0x1000
0x0FFF
0x0000
PROGRAM MEMORY
MODEB = 0
PM OVERLAY 1,2
(EXTERNAL PM)
PM OVERLAY 0
(RESERVED)
RESERVED
INTERNAL PM
0x3FFF
0x3FE0
0x3FDF
0x3000
0x2FFF
0x2000
0x1FFF
0x0000
DATA MEMORY
32 MEMORY-MAPPED
CONTROL REGISTERS
4064 RESERVED
WORDS
INTERNAL DM
DM OVERLAY 1,2
(EXTERNAL DM)
DM OVERLAY 0
(RESERVED)
Figure 4. ADSP-2184 Memory Architecture
Rev. C | Page 8 of 48 | January 2008
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