a
FEATURES
PERFORMANCE
30 ns Instruction Cycle Time 33 MIPS Sustained
Performance
Single-Cycle Instruction Execution
Single-Cycle Context Switch
3-Bus Architecture Allows Dual Operand Fetches in
Every Instruction Cycle
Multifunction Instructions
Power-Down Mode Featuring Low CMOS Standby
Power Dissipation with 100 Cycle Recovery from
Power-Down Condition
Low Power Dissipation in Idle Mode
INTEGRATION
ADSP-2100 Family Code Compatible, with Instruction
Set Extensions
80K Bytes of On-Chip RAM, Configured as
16K Words On-Chip Program Memory RAM and
16K Words On-Chip Data Memory RAM
Dual Purpose Program Memory for Both Instruction
and Data Storage
Independent ALU, Multiplier/Accumulator and Barrel
Shifter Computational Units
Two Independent Data Address Generators
Powerful Program Sequencer Provides
Zero Overhead Looping Conditional Instruction
Execution
Programmable 16-Bit Interval Timer with Prescaler
100-Lead TQFP
SYSTEM INTERFACE
16-Bit Internal DMA Port for High Speed Access to
On-Chip Memory (Mode Selectable)
4 MByte Byte Memory Interface for Storage of Data
Tables & Program Overlays
8-Bit DMA to Byte Memory for Transparent Program
and Data Memory Transfers (Mode Selectable)
I/O Memory Interface with 2048 Locations Supports
Parallel Peripherals (Mode Selectable)
Programmable Memory Strobe & Separate I/O Memory
Space Permits “Glueless” System Design
(Mode Selectable)
Programmable Wait State Generation
Two Double-Buffered Serial Ports with Companding
Hardware and Automatic Data Buffering
Automatic Booting of On-Chip Program Memory from
Byte-Wide External Memory, e.g., EPROM, or
Through Internal DMA Port
*ICE-Port is a trademark of Analog Devices, Inc.
DATA ADDRESS
GENERATORS
DAG 1 DAG 2
PROGRAM
SEQUENCER
DSP Microcomputer
ADSP-2185
FUNCTIONAL BLOCK DIAGRAM
POWER-DOWN
CONTROL
MEMORY
16k 24
PROGRAM
MEMORY
16k 16
DATA
MEMORY
PROGRAMMABLE
I/O
AND
FLAGS
FULL MEMORY
MODE
EXTERNAL
ADDRESS
BUS
EXTERNAL
DATA
BUS
BYTE DMA
CONTROLLER
PROGRAM MEMORY ADDRESS
DATA MEMORY ADDRESS
PROGRAM MEMORY DATA
OR
DATA MEMORY DATA
EXTERNAL
DATA
BUS
ARITHMETIC UNITS
ALU
MAC
SHIFTER
SERIAL PORTS
SPORT 0
SPORT 1
TIMER
INTERNAL
DMA
PORT
HOST MODE
ADSP-2100 BASE
ARCHITECTURE
Six External Interrupts
13 Programmable Flag Pins Provide Flexible System
Signaling
UART Emulation through Software SPORT Reconfiguration
ICE-Port™* Emulator Interface Supports Debugging
in Final Systems
GENERAL NOTE
This data sheet represents production grade specifications for
the ADSP-2185 (5 V).
GENERAL DESCRIPTION
The ADSP-2185 is a single-chip microcomputer optimized for
digital signal processing (DSP) and other high speed numeric
processing applications.
The ADSP-2185 combines the ADSP-2100 family base archi-
tecture (three computational units, data address generators and
a program sequencer) with two serial ports, a 16-bit internal
DMA port, a byte DMA port, a programmable timer, Flag I/O,
extensive interrupt capabilities and on-chip program and data
memory.
The ADSP-2185 integrates 80K bytes of on-chip memory con-
figured as 16K words (24-bit) of program RAM and 16K words
(16-bit) of data RAM. Power-down circuitry is also provided to
meet the low power needs of battery operated portable equip-
ment. The ADSP-2185 is available in 100-pin TQFP package.
In addition, the ADSP-2185 supports new instructions, which
include bit manipulations—bit set, bit clear, bit toggle, bit test—
new ALU constants, new multiplication instruction (x squared),
biased rounding, result free ALU operations, I/O memory trans-
fers and global interrupt masking, for increased flexibility.
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
World Wide Web Site: http://www.analog.com
Fax: 617/326-8703
© Analog Devices, Inc., 1997
ADSP-2185
Fabricated in a high speed, double metal, low power, 0.5
µm
CMOS process, the ADSP-2185 operates with a 30 ns instruc-
tion cycle time. Every instruction can execute in a single proces-
sor cycle.
The ADSP-2185’s flexible architecture and comprehensive
instruction set allow the processor to perform multiple opera-
tions in parallel. In one processor cycle the ADSP-2185 can:
•
•
•
•
•
generate the next program address
fetch the next instruction
perform one or two data moves
update one or two data address pointers
perform a computational operation
The EZ-ICE
®
* performs a full range of functions, including:
•
•
•
•
•
•
•
•
In-target operation
Up to 20 breakpoints
Single-step or full-speed operation
Registers and memory values can be examined and altered
PC upload and download functions
Instruction-level emulation of program booting and execution
Complete assembly and disassembly of instructions
C source-level debugging
This takes place while the processor continues to:
• receive and transmit data through the two serial ports
• receive and/or transmit data through the internal DMA port
• receive and/or transmit data through the byte DMA port
• decrement timer
Development System
See Designing An EZ-ICE
®
*-Compatible Target System in the
ADSP-2100 Family EZ-Tools Manual
(ADSP-2181 sections) as
well as the Target Board Connector for EZ-ICE
®
* Probe sec-
tion of this data sheet for the exact specifications of the EZ-ICE
®
*
target board connector.
Additional Information
The ADSP-2100 Family Development Software, a complete set
of tools for software and hardware system development, sup-
ports the ADSP-2185. The System Builder provides a high level
method for defining the architecture of systems under develop-
ment. The Assembler has an algebraic syntax that is easy to
program and debug. The Linker combines object files into an
executable file. The Simulator provides an interactive instruction-
level simulation with a reconfigurable user interface to display
different portions of the hardware environment. A PROM
Splitter generates PROM programmer compatible files. The
C Compiler, based on the Free Software Foundation’s GNU
C Compiler, generates ADSP-2185 assembly source code. The
source code debugger allows programs to be corrected in the
C environment. The Runtime Library includes over 100 ANSI-
standard mathematical and DSP-specific functions.
The EZ-KIT Lite is a hardware/software kit offering a complete
development environment for the entire ADSP-21xx family: an
ADSP-218x based evaluation board with PC monitor software
plus Assembler, Linker, Simulator and PROM Splitter software.
The ADSP-21xx EZ-KIT Lite is a low cost, easy to use hard-
ware platform on which you can quickly get started with your
DSP software design. The EZ-KIT Lite includes the following
features:
• 33 MHz ADSP-2181
• Full 16-bit Stereo Audio I/O with AD1847 SoundPort
®
* Codec
• RS-232 Interface to PC with Windows
®
3.1 Control Software
• Stand-Alone Operation with Socketed EPROM
• EZ-ICE
®*
Connector for Emulator Control
• DSP Demo Programs
The ADSP-218x EZ-ICE
®
* Emulator aids in the hardware
debugging of an ADSP-2185 system. The emulator consists of
hardware, host computer resident software, and the target board
connector. The ADSP-2185 integrates on-chip emulation sup-
port with a 14-pin ICE-PORT™* interface. This interface pro-
vides a simpler target board connection that requires fewer
mechanical clearance considerations than other ADSP-2100
Family EZ-ICE
®
*s. The ADSP-2185 device need not be removed
from the target system when using the EZ-ICE
®
*, nor are any
adapters needed. Due to the small footprint of the EZ-ICE
®
*
connector, emulation can be supported in final board designs.
*All trademarks are the property of their respective holders.
*EZ-ICE and SoundPORT are registered trademarks of Analog Devices, Inc.
This data sheet provides a general overview of ADSP-2185
functionality. For additional information on the architecture and
instruction set of the processor, refer to the
ADSP-2100 Family
User’s Manual.
For more information about the development
tools, refer to the
ADSP-2100 Family Development Tools Data
Sheet.
ARCHITECTURE OVERVIEW
The ADSP-2185 instruction set provides flexible data moves
and multifunction (one or two data moves with a computation)
instructions. Every instruction can be executed in a single pro-
cessor cycle. The ADSP-2185 assembly language uses an alge-
braic syntax for ease of coding and readability. A comprehensive
set of development tools supports program development.
POWER-DOWN
CONTROL
DATA ADDRESS
GENERATORS
DAG 1 DAG 2
MEMORY
PROGRAM
SEQUENCER
16k 24
PROGRAM
MEMORY
16k 16
DATA
MEMORY
PROGRAMMABLE
I/O
AND
FLAGS
FULL MEMORY
MODE
EXTERNAL
ADDRESS
BUS
EXTERNAL
DATA
BUS
BYTE DMA
CONTROLLER
PROGRAM MEMORY ADDRESS
DATA MEMORY ADDRESS
PROGRAM MEMORY DATA
OR
DATA MEMORY DATA
EXTERNAL
DATA
BUS
ARITHMETIC UNITS
ALU
MAC
SHIFTER
SERIAL PORTS
SPORT 0
SPORT 1
TIMER
INTERNAL
DMA
PORT
HOST MODE
ADSP-2100 BASE
ARCHITECTURE
Figure 1. Block Diagram
Figure 1 is an overall block diagram of the ADSP-2185. The
processor contains three independent computational units: the
ALU, the multiplier/accumulator (MAC) and the shifter. The
computational units process 16-bit data directly and have provi-
sions to support multiprecision computations. The ALU per-
forms a standard set of arithmetic and logic operations; division
primitives are also supported. The MAC performs single-cycle
multiply, multiply/add and multiply/subtract operations with 40
bits of accumulation. The shifter performs logical and arith-
metic shifts, normalization, denormalization and derive expo-
nent operations.
The shifter can be used to efficiently implement numeric
format control including multiword and block floating-point
representations.
–2–
REV. 0
ADSP-2185
The internal result (R) bus connects the computational units so
the output of any unit may be the input of any unit on the next
cycle.
A powerful program sequencer and two dedicated data address
generators ensure efficient delivery of operands to these compu-
tational units. The sequencer supports conditional jumps, sub-
routine calls and returns in a single cycle. With internal loop
counters and loop stacks, the ADSP-2185 executes looped code
with zero overhead; no explicit jump instructions are required to
maintain loops.
Two data address generators (DAGs) provide addresses for
simultaneous dual operand fetches from data memory and pro-
gram memory. Each DAG maintains and updates four address
pointers. Whenever the pointer is used to access data (indirect
addressing), it is post-modified by the value of one of four pos-
sible modify registers. A length value may be associated with
each pointer to implement automatic modulo addressing for
circular buffers.
Efficient data transfer is achieved with the use of five internal
buses:
• Program Memory Address (PMA) Bus
• Program Memory Data (PMD) Bus
• Data Memory Address (DMA) Bus
• Data Memory Data (DMD) Bus
• Result (R) Bus
The two address buses (PMA and DMA) share a single external
address bus, allowing memory to be expanded off-chip, and the
two data buses (PMD and DMD) share a single external data
bus. Byte memory space and I/O memory space also share the
external buses.
Program memory can store both instructions and data, permit-
ting the ADSP-2185 to fetch two operands in a single cycle, one
from program memory and one from data memory. The ADSP-
2185 can fetch an operand from program memory and the next
instruction in the same cycle.
When configured in host mode, the ADSP-2185 has a 16-bit
Internal DMA port (IDMA port) for connection to external
systems. The IDMA port is made up of 16 data/address pins
and five control pins. The IDMA port provides transparent,
direct access to the DSPs on-chip program and data RAM.
An interface to low cost byte-wide memory is provided by the
Byte DMA port (BDMA port). The BDMA port is bidirectional
and can directly address up to four megabytes of external RAM
or ROM for off-chip storage of program overlays or data tables.
The byte memory and I/O memory space interface supports
slow memories and I/O memory-mapped peripherals with
programmable wait state generation. External devices can
gain control of external buses with bus request/grant signals
(BR,
BGH
and
BG).
One execution mode (Go Mode) allows
the ADSP-2185 to continue running from on-chip memory.
Normal execution mode requires the processor to halt while
buses are granted.
The ADSP-2185 can respond to eleven interrupts. There can be
up to six external interrupts (one edge-sensitive, two level-sensitive
and three configurable) and seven internal interrupts generated
by the timer, the serial ports (SPORTs), the Byte DMA port
and the power-down circuitry. There is also a master
RESET
signal. The two serial ports provide a complete synchronous
serial interface with optional companding in hardware and a
REV. 0
wide variety of framed or frameless data transmit and receive
modes of operation.
Each port can generate an internal programmable serial clock or
accept an external serial clock.
The ADSP-2185 provides up to 13 general-purpose flag pins.
The data input and output pins on SPORT1 can be alternatively
configured as an input flag and an output flag. In addition,
eight flags are programmable as inputs or outputs, and three
flags are always outputs.
A programmable interval timer generates periodic interrupts. A
16-bit count register (TCOUNT) decrements every
n
processor
cycle, where
n
is a scaling value stored in an 8-bit register
(TSCALE). When the value of the count register reaches zero,
an interrupt is generated and the count register is reloaded from
a 16-bit period register (TPERIOD).
Serial Ports
The ADSP-2185 incorporates two complete synchronous serial
ports (SPORT0 and SPORT1) for serial communications and
multiprocessor communication.
Here is a brief list of the capabilities of the ADSP-2185 SPORTs.
For additional information on Serial Ports, refer to the
ADSP-
2100 Family User’s Manual.
• SPORTs are bidirectional and have a separate, double-buff-
ered transmit and receive section.
• SPORTs can use an external serial clock or generate their own
serial clock internally.
• SPORTs have independent framing for the receive and trans-
mit sections. Sections run in a frameless mode or with frame
synchronization signals internally or externally generated.
Frame sync signals are active high or inverted, with either of
two pulse widths and timings.
• SPORTs support serial data word lengths from 3 to 16 bits
and provide optional A-law and
µ-law
companding according
to CCITT recommendation G.711.
• SPORT receive and transmit sections can generate unique
interrupts on completing a data word transfer.
• SPORTs can receive and transmit an entire circular buffer of
data with only one overhead cycle per data word. An interrupt
is generated after a data buffer transfer.
• SPORT0 has a multichannel interface to selectively receive
and transmit a 24 or 32 word, time-division multiplexed,
serial bitstream.
• SPORT1 can be configured to have two external interrupts
(IRQ0 and
IRQ1)
and the Flag In and Flag Out signals. The
internally generated serial clock may still be used in this con-
figuration.
PIN DESCRIPTIONS
The ADSP-2185 will be available in a 100-lead TQFP package.
In order to maintain maximum functionality and reduce pack-
age size and pin count, some serial port, programmable flag,
interrupt and external bus pins have dual, multiplexed function-
ality. The external bus pins are configured during RESET only,
while serial port pins are software configurable during program
execution. Flag and interrupt functionality is retained concur-
rently on multiplexed pins. In cases where pin functionality is
reconfigurable, the default state is shown in plain text; alternate
functionality is shown in italics.
–3–
ADSP-2185
Common-Mode Pins
Pin
Name(s)
#
of
Pins
Input/
Out-
put
Function
Memory Interface Pins
RESET
BR
BG
BGH
DMS
PMS
IOMS
BMS
CMS
RD
WR
IRQ2/
PF7
IRQL0/
PF5
IRQL1/
PF6
IRQE/
PF4
PF3
Mode C/
PF2
Mode B/
PF1
Mode A/
PF0
CLKIN, XTAL
CLKOUT
SPORT0
SPORT1/
IRQ1:0
FI, FO
PWD
PWDACK
FL0, FL1, FL2
VDD and GND
EZ-Port
1
1
1
1
1
1
1
1
1
1
1
1
I
I
O
O
O
O
O
O
O
O
O
I
I/O
I
I/O
I
I/O
I
I/O
I/O
I
I/O
1
1
1
1
1
1
I
I/O
1
I
I/O
2
1
5
5
I
O
I/O
I/O
1
1
3
16
9
I
O
O
I
I/O
Processor Reset Input
Bus Request Input
Bus Grant Output
Bus Grant Hung Output
Data Memory Select Output
Program Memory Select Output
Memory Select Output
Byte Memory Select Output
Combined Memory Select Output
Memory Read Enable Output
Memory Write Enable Output
Edge- or Level-Sensitive
Interrupt Request
1
Programmable I/O Pin
Level-Sensitive Interrupt Requests
1
Programmable I/O Pin
Level-Sensitive Interrupt Requests
1
Programmable I/O Pin
Edge-Sensitive Interrupt Requests
1
Programmable I/O Pin
Programmable I/O Pin
Mode Select Input—Checked
only During RESET
Programmable I/O Pin During
Normal Operation
Mode Select Input—Checked
only During RESET
Programmable I/O Pin During
Normal Operation
Mode Select Input—Checked
only During RESET
Programmable I/O Pin During
Normal Operation
Clock or Quartz Crystal Input
Processor Clock Output
Serial Port I/O Pins
Serial Port I/O Pins
Edge- or Level-Sensitive Interrupts,
Flag In, Flag Out
2
Power-Down Control Input
Power-Down Control Output
Output Flags
Power and Ground
For Emulation Use
The ADSP-2185 processor can be used in one of two modes,
Full Memory Mode, which allows BDMA operation with full
external overlay memory and I/O capability, or Host Mode,
which allows IDMA operation with limited external addressing
capabilities. The operating mode is determined by the state of
the Mode C pin during RESET and cannot be changed while
the processor is running.
Full Memory Mode Pins (Mode C = 0)
Pin Name
A13:0
#
of
Pins
14
Input/
Output
O
Function
Address Output Pins for Pro-
gram, Data, Byte and I/O
Spaces
Data I/O Pins for Program,
Data, Byte and I/O Spaces
(8 MSBs Are Also Used as
Byte Memory Addresses)
D23:0
24
I/O
Host Mode Pins (Mode C = 1)
Pin Name
IAD15:0
A0
D23:8
IWR
IRD
IAL
IS
IACK
#
of
Pins
16
1
16
1
1
1
1
1
Input/
Output
I/O
O
I/O
I
I
I
I
O
Function
IDMA Port Address/Data Bus
Address Pin for External I/O,
Program, Data, or Byte Access
Data I/O Pins for Program,
Data Byte and I/O Spaces
IDMA Write Enable
IDMA Read Enable
IDMA Address Latch Pin
IDMA Select
IDMA Port Acknowledge
In Host Mode, external peripheral addresses can be decoded using the A0,
CMS, PMS, DMS,
and
IOMS
signals
Setting Memory Mode
Memory Mode selection for the ADSP-2185 is made during
chip reset through the use of the Mode C pin. This pin is multi-
plexed with the DSP’s PF2 pin, so care must be taken in how
the mode selection is made. The two methods for selecting the
value of Mode C are active and passive.
Passive configuration involves the use a pull-up or pull-down
resistor connected to the Mode C pin. To minimize power
consumption, or if the PF2 pin is to be used as an output in the
DSP application, a weak pull-up or pull-down, on the order of
100 kΩ, can be used. This value should be sufficient to pull the
pin to the desired level and still allow the pin to operate as a
programmable flag output without undue strain on the processor’s
output driver. For minimum power consumption during
power-down, reconfigure PF2 to be an input as the pull-up or
pull-down will hold the pin in a known state and will not switch.
Active configuration involves the use of a three-stateable exter-
nal driver connected to the Mode C pin. A driver’s output en-
able should be connected to the DSP’s
RESET
signal such that
it only drives the PF2 pin when
RESET
is active (low). After
–4–
REV. 0
NOTES
1
Interrupt/Flag pins retain both functions concurrently. If IMASK is set to
enable the corresponding interrupts, the DSP will vector to the appropriate
interrupt vector address when the pin is asserted, either by external devices or
set as a programmable flag.
2
SPORT configuration determined by the DSP System Control Register. Soft-
ware configurable.
ADSP-2185
RESET is deasserted, the driver should three-state, thus allow-
ing full use of the PF2 pin as either an input or output.
To minimize power consumption during power-down, configure
the programmable flag as an output when connected to a three-
stated buffer. This ensures that the pin will be held at a constant
level and not oscillate should the three-state driver’s level hover
around the logic switching point.
Interrupts
The IFC register is a write-only register used to force and clear
interrupts.
On-chip stacks preserve the processor status and are automati-
cally maintained during interrupt handling. The stacks are twelve
levels deep to allow interrupt, loop and subroutine nesting.
The following instructions allow global enable or disable servic-
ing of the interrupts (including power-down), regardless of the
state of IMASK. Disabling the interrupts does not affect serial
port autobuffering or DMA.
ENA INTS;
DIS INTS;
When the processor is reset, interrupt servicing is enabled.
LOW POWER OPERATION
The interrupt controller allows the processor to respond to the
eleven possible interrupts and reset with minimum overhead.
The ADSP-2185 provides four dedicated external interrupt
input pins,
IRQ2, IRQL0, IRQL1
and
IRQE
(shared with the
PF7:4 pins). In addition, SPORT1 may be reconfigured for
IRQ0, IRQ1,
FLAG_IN and FLAG_OUT, for a total of six
external interrupts. The ADSP-2185 also supports internal
interrupts from the timer, the byte DMA port, the two serial
ports, software and the power-down control circuit. The inter-
rupt levels are internally prioritized and individually maskable
(except power-down and reset). The
IRQ2, IRQ0
and
IRQ1
input pins can be programmed to be either level- or edge-sensitive.
IRQL0
and
IRQL1
are level-sensitive and IRQE is edge-sensitive.
The priorities and vector addresses of all interrupts are shown in
Table I.
Table I. Interrupt Priority & Interrupt Vector Addresses
The ADSP-2185 has three low power modes that significantly
reduce the power dissipation when the device operates under
standby conditions. These modes are:
• Power-Down
• Idle
• Slow Idle
The CLKOUT pin may also be disabled to reduce external
power dissipation.
Power-Down
Source Of Interrupt
Reset (or Power-Up with
PUCR = 1)
Power-down (Nonmaskable)
IRQ2
IRQL1
IRQL0
SPORT0 Transmit
SPORT0 Receive
IRQE
BDMA Interrupt
SPORT1 Transmit or
IRQ1
SPORT1 Receive or
IRQ0
Timer
Interrupt Vector Address (Hex)
0000 (Highest Priority)
002C
0004
0008
000C
0010
0014
0018
001C
0020
0024
0028 (Lowest Priority)
The ADSP-2185 processor has a low power feature that lets the
processor enter a very low power dormant state through hard-
ware or software control. Here is a brief list of power-down
features. Refer to the
ADSP-2100 Family User’s Manual,
“System
Interface” chapter, for detailed information about the power-
down feature.
• Quick recovery from power-down. The processor begins
executing instructions in as few as 100 CLKIN cycles.
• Support for an externally generated TTL or CMOS proces-
sor clock. The external clock can continue running during
power-down without affecting the lowest power rating and
100 CLKIN cycle recovery.
• Support for crystal operation includes disabling the oscillator
to save power (the processor automatically waits approxi-
mately 4096 CLKIN cycles for the crystal oscillator to start
or stabilize), and letting the oscillator run to allow 100 CLKIN
cycle start-up.
• Power-down is initiated by either the power-down pin (PWD)
or the software power-down force bit.
• Interrupt support allows an unlimited number of instructions
to be executed before optionally powering down. The power-
down interrupt also can be used as a nonmaskable, edge-
sensitive interrupt.
• Context clear/save control allows the processor to continue
where it left off or start with a clean context when leaving the
power-down state.
• The
RESET
pin also can be used to terminate power-down.
• Power-down acknowledge pin indicates when the processor
has entered power-down.
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 power-down interrupt is nonmaskable.
The ADSP-2185 masks all interrupts for one instruction cycle
following the execution of an instruction that modifies the
IMASK register. This does not affect serial port autobuffering
or DMA transfers.
The interrupt control register, ICNTL, controls interrupt nest-
ing and defines the
IRQ0, IRQ1
and
IRQ2
external interrupts to
be either edge- or level-sensitive. The
IRQE
pin is an external
edge-sensitive interrupt and can be forced and cleared. The
IRQL0
and
IRQL1
pins are external level-sensitive interrupts.
REV. 0
–5–
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