adsp-21992 Analog Devices, Inc., adsp-21992 Datasheet - Page 12

• Manufacturer Part Number: adsp-21992
• Description: Mixed Signal Dsp Controller With Can
• Manufacturer: Analog Devices, Inc.

ADSP-21992
Table 2. Interrupt Priorities/Addresses (Continued)
There is no assigned priority for the peripheral interrupts after
reset. To assign the peripheral interrupts a different priority,
applications write the new priority to their corresponding con-
trol bits (determined by their ID) in the interrupt priority
control register.
Interrupt routines can either be nested with higher priority
interrupts taking precedence or processed sequentially. Inter-
rupts can be masked or unmasked with the IMASK register.
Individual interrupt requests are logically ANDed with the bits
in IMASK; the highest priority unmasked interrupt is then
selected. The emulation, power-down, and reset interrupts are
nonmaskable with the IMASK register, but software can use the
DIS INT instruction to mask the power-down interrupt.
The interrupt control (ICNTL) register controls interrupt nest-
ing and enables or disables interrupts globally.
The IRPTL register is used to force and clear interrupts. On-
chip stacks preserve the processor status and are automatically
maintained during interrupt handling. To support interrupt,
loop, and subroutine nesting, the PC stack is 33 levels deep, the
Interrupt
User Assigned Interrupt
(USR1)
User Assigned Interrupt
(USR2)
User Assigned Interrupt
(USR3)
User Assigned Interrupt
(USR4)
User Assigned Interrupt
(USR5)
User Assigned Interrupt
(USR6)
User Assigned Interrupt
(USR7)
User Assigned Interrupt
(USR8)
User Assigned Interrupt
(USR9)
User Assigned Interrupt
(USR10)
User Assigned Interrupt
(USR11)
—Lowest Priority
IMASK/
IRPTL
5
6
7
8
9
10
11
12
13
14
15
Vector Address
0x00 00A0
0x00 00C0
0x00 00E0
0x00 0100
0x00 0120
0x00 0140
0x00 0160
0x00 0180
0x00 01A0
0x00 01C0
0x00 01E0
Rev. A | Page 12 of 60 | August 2007
loop stack is eight levels deep, and the status stack is 16 levels
deep. To prevent stack overflow, the PC stack can generate a
stack level interrupt if the PC stack falls below three locations
full or rises above 28 locations full.
The following instructions globally enable or disable interrupt
servicing, regardless of the state of IMASK.
At reset, interrupt servicing is disabled.
For quick servicing of interrupts, a secondary set of DAG and
computational registers exist. Switching between the primary
and secondary registers lets programs quickly service interrupts,
while preserving the state of the DSP.
PERIPHERAL INTERRUPT CONTROLLER
The peripheral interrupt controller is a dedicated peripheral
unit of the ADSP-21992 (accessed via I/O mapped registers).
The peripheral interrupt controller manages the connection of
up to 32 peripheral interrupt requests to the DSP core.
For each peripheral interrupt source, there is a unique 4-bit
code that allows the user to assign the particular peripheral
interrupt to any one of the 12 user assignable interrupts of the
embedded ADSP-2199x core. Therefore, the peripheral inter-
rupt controller of the ADSP-21992 contains eight 16-bit
interrupt priority registers (Interrupt Priority Register 0 (IPR0)
to Interrupt Priority Register 7 (IPR7)).
Each interrupt priority register contains four 4-bit codes; one
specifically assigned to each peripheral interrupt. The user may
write a value between 0x0 and 0xB to each 4-bit location in
order to effectively connect the particular interrupt source to
the corresponding user assignable interrupt of the
ADSP-2199x core.
Writing a value of 0x0 connects the peripheral interrupt to the
USR0 user assignable interrupt of the ADSP-2199x core while
writing a value of 0xB connects the peripheral interrupt to the
USR11 user assignable interrupt. The core interrupt USR0 is the
highest priority user interrupt, while USR11 is the lowest prior-
ity. Writing a value between 0xC and 0xF effectively disables the
peripheral interrupt by not connecting it to any ADSP-2199x
core interrupt input. The user may assign more than one
peripheral interrupt to any given ADSP-2199x core interrupt. In
that case, the burden is on the user software in the interrupt vec-
tor table to determine the exact interrupt source through
reading status bits.
This scheme permits the user to assign the number of specific
interrupts that are unique to their application to the interrupt
scheme of the ADSP-2199x core. The user can then use the
existing interrupt priority control scheme to dynamically con-
trol the priorities of the 12 core interrupts.
LOW POWER OPERATION
The ADSP-21992 has four low power options that significantly
reduce the power dissipation when the device operates under
standby conditions. To enter any of these modes, the DSP exe-
cutes an IDLE instruction. The ADSP-21992 uses the
• Ena Int
• Dis Int