adsp-21msp58 Analog Devices, Inc., adsp-21msp58 Datasheet - Page 8

• Manufacturer Part Number: adsp-21msp58
• Description: Dsp Microcomputers
• Manufacturer: Analog Devices, Inc.

ADSP-21msp58/59
wait-state configuration, host interface port, codec, and serial
port operations are located in this region of memory.
The remaining 12K of data memory is external. External data
memory is divided into three zones, each associated with its own
wait-state generator. By mapping peripherals into different
zones, you can accommodate peripherals with different wait-
state requirements. All zones default to seven wait states after
RESET.
For compatibility with other ADSP-2100 Family processors, bit
definitions for DWAIT3 and DWAIT4 are shown in the Data
Memory Wait State Control register, but they are not used by
the ADSP-21msp58/59.
Boot Memory Interface
The ADSP-21msp58/59 can load on-chip memory from exter-
nal boot memory space. The boot memory space consists of
64K by 8-bit space, divided into eight separate 8K by 8-bit
pages. Three bits in the System Control Register select which
page is loaded by the boot memory interface. Another bit in the
System Control Register allows the user to force a boot loading
sequence under software control. Boot loading from Page 0 after
RESET is initiated automatically if MMAP = 0.
The boot memory interface can generate zero to seven wait
states; it defaults to seven wait states after RESET. This allows
the ADSP-21msp58/59 to boot from a single low cost EPROM
such as a 27C256. Program memory is booted one byte at a
time and converted to 24-bit program memory words.
The BMS and RD signals are used to select and to strobe the
boot memory interface. Only 8-bit data is read over the data
bus, on pins D8–D15. To accommodate addressing up to eight
pages of boot memory, the two MSBs of the data bus are used
in the boot memory interface as the two MSBs of the boot
memory address.
The ADSP-2100 Family Assembler and Linker support the cre-
ation of programs and data structures requiring multiple boot
pages during execution.
RD and WR must always be qualified by PMS, DMS, or BMS
to ensure the correct program, data, or boot memory accessing.
Figure 7. ADSP-21msp58/59 Data Memory Maps
NO WAIT STATES
(10K EXTERNAL)
(1K EXTERNAL)
(1K EXTERNAL)
WAIT STATES
DWAIT2
DWAIT0
DWAIT1
0000
03FF
0400
3FFF
07FF
0800
2FFF
3000
MEMORY MAPPED
AND RESERVED
DATA MEMORY
REGISTERS
RESERVED
EXTERNAL
INTERNAL
12K
1K
2K
0000
2FFF
3000
37FF
3800
3BFF
3C00
3FFF
–8–
HIP Booting
The ADSP-21msp58/59 can also boot programs through the
Host Interface Port. If BMODE = 1 and MMAP = 0, the
ADSP-21msp58/59 boots from the HIP. If BMODE = 0, the
ADSP-21msp58/59 boots through the data bus (in the same
way as the ADSP-2101), as described above in “Boot Memory
Interface.” For additional information about HIP booting, refer
to the ADSP-2100 Family User’s Manual, Chapter 7, “Host In-
terface Port.”
The ADSP-2100 Family Development Software includes a
utility program called the HIP Splitter. This utility allows the
creation of programs that can be booted through the ADSP-
21msp58/59 HIP, in a similar fashion as EPROM-bootable
programs generated by the PROM Splitter utility.
Bus Request and Bus Grant
The ADSP-21msp58/59 can relinquish control of the data and
address buses to an external device. When the external device
requires access to memory, it asserts the bus request signal
(BR). If the ADSP-21msp58/59 is not performing an external
memory access, it responds to the active BR input in the follow-
ing processor cycle by
• three-stating the data and address buses and the PMS, DMS,
• asserting the bus grant (BG) signal, and
• halting program execution.
If GoMode is enabled, the ADSP-21msp58/59 will not halt pro-
gram execution until it encounters an instruction that requires
an external memory access.
If the ADSP-21msp58/59 is performing an external memory ac-
cess when the external device asserts the BR signal, then it will
not three-state the memory interfaces or assert the BG signal
until the cycle after the access is completed, which can be up to
eight cycles later depending on the number of wait states. The
instruction does not need to be completed when the bus is
granted. If a single instruction requires two external memory
accesses, the bus will be granted between the two accesses.
When the BR signal is released, the processor releases the BG
signal, which reenables the output drivers, and continues pro-
gram execution from the point where it stopped.
The bus request feature operates at all times, including when
the processor is booting and when RESET is active.
LOW POWER OPERATION
The ADSP-21msp58/59 has three low power modes that signifi-
cantly reduce the power dissipation when the device operates
under standby conditions. These modes are:
• Powerdown
• Idle
• Slow Idle
The CLKOUT pin may also be disabled to reduce external
power dissipation. The CLKOUT pin is controlled by Bit 14 of
SPORT0 Autobuffer Control Register, DM[0x3FF3].
Powerdown
The ADSP-21msp58/59 has a low power feature that lets the
processors enter a very low power dormant state through hard-
ware or software control. Here is a brief list of powerdown fea-
tures. Refer to the ADSP-2100 Family User’s Manual, Chapter 9,
BMS, RD, and WR output drivers,
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