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10
6/2001
REV. PrB
For current information contact Analog Devices at (800) ANALOGD
ADSP-21mod980N
PRELIMINARY TECHNICAL DATA
A clock output (CLKOUT) signal is generated by the pro-
cessor at the processor
’
s cycle rate. This can be enabled and
disabled by the CLKODIS bit in the SPORT0 Autobuffer
Control Register.
RESET
The RESET signals initiate a reset of each modem proces-
sor in the ADSP-21mod980N. The RESET signals must be
asserted during the power-up sequence to assure proper ini-
tialization. RESET during initial power-up must be held
long enough to let the internal clocks stabilize. If RESETs
are activated any time after power up, the clocks continue to
run and do not require stabilization time.
The power-up sequence is defined as the total time required
for the oscillator circuits to stabilize after a valid V
DD
is
applied to the processors, and for the internal phase-locked
loops (PLL) to lock onto the specific frequency. A mini-
mum of 2000 CLKIN cycles ensures that the PLLs have
locked, but this does not include the oscillators
’
start-up
time. During this power-up sequence, the RESET signals
should be held low. On any subsequent resets, the RESET
signals must meet the minimum pulse width specification,
t
RSP
.
The RESET input contains some hysteresis; however, if you
use an RC circuit to generate your RESET signals, the use
of an external Schmidt triggers are recommended.
The RESET for each individual modem processor sets the
internal stack pointers to the empty stack condition, masks
all interrupts and clears the MSTAT register. When a
RESET is released, if there is no pending bus request and
the modem processor 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-21mod980N provides a variety of memory and
peripheral interface options for Modem Processor 1. The
key functional groups are Program Memory, Data Memory,
Byte Memory, and I/O. Refer to the following figures and
tables for PM and DM memory allocations in the
ADSP-21mod980N.
The ADSP-21mod980N modem pool operates in one
memory mode: Slave Mode. The following figures and
tables describe the memory of the ADSP-21mod980N:
Figure on page 10
shows Program Memory
Table on page 10
shows the generation of address bits
based on the PMOVLAY values
Figure on page 11
shows Data Memory
Table on page 11
shows the generation of address bits
based on the DMOVLAY values. Access to external
memory is not available
Figure 4. Program Memory Map
Table 4. PMOVLAY bits
PMOVLAY
Memory
A13
A[12:0]
0, 4, 5, 6, 7
Internal
Not
Applicable
Not Applicable
0x2000 -
0x3FFF
ACCESSIBLE
WHEN
PM OVLAY = 7
0x2000 -
0x3FFF
ACCESSIBLE
WHEN
PM OVLAY = 6
0x2000 -
0x3FFF
ACCESSIBLE WHEN
PM OVLAY = 5
PM OVLAY = 0
ACCESSIBLE WHEN
0x2000 -
0x3FFF
0x2000 -
0x3FFF
ACCESSIBLE WHEN
PM OVLAY = 4
PM MODE B = 0
ALWAYS
ACCESSIBLE
AT ADDRESS
0x0000 - 0x1FFF
0x3FFF
8K
INTERNAL
0x0000
8K INTERNAL
PMOVLAY =
0, 4, 5, 6, 7
0x1FFF
0x2000
PROGRAM MEMORY
MODE B=0
ADDRESS
INTERNAL
MEMORY