Analog Devices ADSP-2181BST-115, ADSP-2181BS-133, ADSP-2181BS-115, ADSP-2181KST-160, ADSP-2181KST-133 Datasheet
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EXTERNAL
ADDRESS
BUS
EXTERNAL
DATA BUS
DMA BUS
SERIAL PORTS
SPORT 1SPORT 0
MEMORY
PROGRAM
MEMORY
DATA
MEMORY
PROGRAMMABLE
I/O
FLAGS
BYTE DMA
CONTROLLER
TIMER
ADSP-2100 BASE
ARCHITECTURE
SHIFTERMACALU
ARITHMETIC UNITS
POWER-DOWN
CONTROL
PROGRAM
SEQUENCER
DAG 2DAG 1
DATA ADDRESS
GENERATORS
PROGRAM MEMORY ADDRESS
DATA MEMORY ADDRESS
PROGRAM MEMORY DATA
DATA MEMORY DATA
INTERNAL
DMA
PORT
a
DSP Microcomputer
ADSP-2181
FEATURES
PERFORMANCE
25 ns Instruction Cycle Time from 20 MHz Crystal
@ 5.0 Volts
40 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
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
128-Lead TQFP/128-Lead PQFP
SYSTEM INTERFACE
16-Bit Internal DMA Port for High Speed Access to
On-Chip Memory
4 MByte Memory Interface for Storage of Data Tables
and Program Overlays
8-Bit DMA to Byte Memory for Transparent
Program and Data Memory Transfers
I/O Memory Interface with 2048 Locations Supports
Parallel Peripherals
Programmable Memory Strobe and Separate I/O Memory
Space Permits “Glueless” System Design
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
Six External Interrupts
13 Programmable Flag Pins Provide Flexible System
Signaling
ICE-Port™ Emulator Interface Supports Debugging
in Final Systems
ICE-Port is a trademark of Analog Devices, Inc.
REV. D
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.
FUNCTIONAL BLOCK DIAGRAM
GENERAL DESCRIPTION
The ADSP-2181 is a single-chip microcomputer optimized for
digital signal processing (DSP) and other high speed numeric
processing applications.
The ADSP-2181 combines the ADSP-2100 family base architecture (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-2181 integrates 80K bytes of on-chip memory configured 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 equipment. The ADSP-2181 is available in 128-lead TQFP and 128lead PQFP packages.
In addition, the ADSP-2181 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 transfers and global interrupt masking for increased flexibility.
Fabricated in a high speed, double metal, low power, CMOS
process, the ADSP-2181 operates with a 25 ns instruction cycle
time. Every instruction can execute in a single processor cycle.
The ADSP-2181’s flexible architecture and comprehensive
instruction set allow the processor to perform multiple operations in parallel. In one processor cycle the ADSP-2181 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
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 1998
ADSP-2181
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
The ADSP-2100 Family Development Software, a complete
set of tools for software and hardware system development,
supports the ADSP-2181. The System Builder provides a high
level method for defining the architecture of systems under
development. 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-2181 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-2181 evaluation board with PC monitor software plus
Assembler, Linker, Simulator, and PROM Splitter software.
The ADSP-218x EZ-KIT Lite is a low-cost, easy to use hardware 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 ADSP-218x systems. The emulator consists of hardware, host computer resident software and the target board
connector. The ADSP-218x integrates on-chip emulation support with a 14-pin ICE-Port interface. This interface provides a
simpler target board connection requiring fewer mechanical
clearance considerations than other ADSP-2100 Family EZ-ICEs.
The ADSP-218x 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.
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
See the Designing An EZ-ICE-Compatible Target System sec-
tion of this data sheet for exact specifications of the EZ-ICE target
board connector.
EZ-ICE and SoundPort are registered trademarks of Analog Devices, Inc.
Additional Information
This data sheet provides a general overview of ADSP-2181
functionality. For additional information on the architecture and
instruction set of the processor, refer to the ADSP-2100 Family
User’s Manual, Third Edition. For more information about the
development tools, refer to the ADSP-2100 Family Development
Tools Data Sheet.
ARCHITECTURE OVERVIEW
The ADSP-2181 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 processor cycle. The ADSP-2181 assembly language uses an algebraic syntax for ease of coding and readability. A comprehensive
set of development tools supports program development.
Figure 1 is an overall block diagram of the ADSP-2181. 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 provisions to support multiprecision computations. The ALU performs 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 arithmetic shifts, normalization, denormalization and derive exponent operations. The shifter can be used to efficiently implement
numeric format control including multiword and block floatingpoint representations.
The internal result (R) bus connects the computational units so
that 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 computational units. The sequencer supports conditional jumps, subroutine
calls and returns in a single cycle. With internal loop counters and
loop stacks, the ADSP-2181 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
program 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 possible 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, permitting the ADSP-2181 to fetch two operands in a single cycle,
one from program memory and one from data memory. The
–2–
REV. D
ADSP-2181
ADSP-2181 can fetch an operand from program memory and
the next instruction in the same cycle.
In addition to the address and data bus for external memory
connection, the ADSP-2181 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-2181 to continue running from on-chip memory. Normal execution mode
requires the processor to halt while buses are granted.
The ADSP-2181 can respond to 13 possible interrupts, eleven
of which are accessible at any given time. 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 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-2181 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, there
are eight flags that are programmable as inputs or outputs and
three flags that are always outputs.
A programmable interval timer generates periodic interrupts. A
16-bit count register (TCOUNT) is decremented every n processor cycles, 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-2181 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-2181 SPORTs.
Refer to the ADSP-2100 Family User’s Manual, Third Edition for
further details.
• SPORTs are bidirectional and have a separate, doublebuffered 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 transmit 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 pulsewidths and timings.
21xx CORE
DATA
ADDRESS
GENERATOR
#1
INPUT REGS INPUT REGS
INPUT REGS
ALU
ALU
OUTPUT REGS
OUTPUT REGS
DATA
ADDRESS
GENERATOR
#2
PMA BUS
DMA BUS
PMD BUS
DMD BUS
OUTPUT REGS
INPUT REGS
MAC
MAC
OUTPUT REGS
16
INSTRUCTION
R BUS
REGISTER
PROGRAM
SEQUENCER
INPUT REGS
OUTPUT REGS
14
14
24
BUS
EXCHANGE
16
SHIFTER
PROGRAM
SRAM
16K 3 24
TRANSMIT REG
ADSP-2181 INTEGRATION
16K 3 16
COMPANDING
CIRCUITRY
RECEIVE REG
SERIAL
PORT 0
5 5
DATA
SRAM
TRANSMIT REG
RECEIVE REG
SERIAL
PORT 0
BYTE
DMA
CONTROLLER
TIMER
POWER-
DOWN
CONTROL
LOGIC
PROGRAMMABLE
I/O
FLAGS
PMA BUS
DMA BUS
PMD BUS
DMD
BUS
INTERNAL
INTERRUPTS
MUX
MUX
DMA
PORT
2
8
3
14
EXTERNAL
ADDRESS
BUS
EXTERNAL
DATA
BUS
24
16
4
REV. D
Figure 1. ADSP-2181 Block Diagram
–3–
ADSP-2181
• 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
configuration.
Pin Descriptions
The ADSP-2181 is available in 128-lead TQFP and 128-lead
PQFP packages.
PIN FUNCTION DESCRIPTIONS
#
Pin of Input/
Name(s) Pins Output Function
Address 14 O Address Output Pins for Program,
Data, Byte, and I/O Spaces
Data 24 I/O Data I/O Pins for Program and
Data Memory Spaces (8 MSBs
Are Also Used as Byte Space
Addresses)
RESET 1 I Processor Reset Input
IRQ2 1 I Edge- or Level-Sensitive
Interrupt Request
IRQL0,
IRQL1 2 I Level-Sensitive Interrupt
Requests
IRQE 1 I Edge-Sensitive Interrupt
Request
BR 1 I Bus Request Input
BG 1 O Bus Grant Output
BGH 1 O Bus Grant Hung Output
PMS 1 O Program Memory Select Output
DMS 1 O Data Memory Select Output
BMS 1 O Byte Memory Select Output
IOMS 1 O I/O Space Memory Select Output
CMS 1 O Combined Memory Select Output
RD 1 O Memory Read Enable Output
WR 1 O Memory Write Enable Output
MMAP 1 I Memory Map Select Input
BMODE 1 I Boot Option Control Input
CLKIN,
XTAL 2 I Clock or Quartz Crystal Input
#
Pin of Input/
Name(s) Pins Output Function
CLKOUT 1 O Processor Clock Output
SPORT0 5 I/O Serial Port I/O Pins
SPORT1 5 I/O Serial Port 1 or Two External
IRQs, Flag In and Flag Out
IRD, IWR 2 I IDMA Port Read/Write Inputs
IS 1 I IDMA Port Select
IAL 1 I IDMA Port Address Latch
Enable
IAD 16 I/O IDMA Port Address/Data Bus
IACK 1 O IDMA Port Access Ready
Acknowledge
PWD 1 I Power-Down Control
PWDACK 1 O Power-Down Control
FL0, FL1,
FL2 3 O Output Flags
PF7:0 8 I/O Programmable I/O Pins
EE 1 * (Emulator Only*)
EBR 1 * (Emulator Only*)
EBG 1 * (Emulator Only*)
ERESET 1 * (Emulator Only*)
EMS 1 * (Emulator Only*)
EINT 1 * (Emulator Only*)
ECLK 1 * (Emulator Only*)
ELIN 1 * (Emulator Only*)
ELOUT 1 * (Emulator Only*)
GND 11 – Ground Pins
VDD 6 – Power Supply Pins
*These ADSP-2181 pins must be connected only to the EZ-ICE connector in
the target system. These pins have no function except during emulation, and
do not require pull-up or pull-down resistors.
Interrupts
The interrupt controller allows the processor to respond to the
eleven possible interrupts and reset with minimum overhead.
The ADSP-2181 provides four dedicated external interrupt
input pins, IRQ2, IRQL0, IRQL1 and IRQE. In addition,
SPORT1 may be reconfigured for IRQ0, IRQ1, FLAG_IN and
FLAG_OUT, for a total of six external interrupts. The ADSP2181 also supports internal interrupts from the timer, the byte
DMA port, the two serial ports, software and the power-down
control circuit. The interrupt 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 levelsensitive and IRQE is edge sensitive. The priorities and vector
addresses of all interrupts are shown in Table I.
–4–
REV. D
ADSP-2181
Table I. Interrupt Priority and Interrupt Vector Addresses
Interrupt Vector
Source of Interrupt Address (Hex)
Reset (or Power-Up with PUCR = 1) 0000 (Highest Priority)
Power-Down (Nonmaskable) 002C
IRQ2 0004
IRQL1 0008
IRQL0 000C
SPORT0 Transmit 0010
SPORT0 Receive 0014
IRQE 0018
BDMA Interrupt 001C
SPORT1 Transmit or IRQ1 0020
SPORT1 Receive or IRQ0 0024
Timer 0028 (Lowest Priority)
Interrupt routines can either be nested with higher priority
interrupts taking precedence or processed sequentially. Interrupts 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-2181 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 nesting 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.
The IFC register is a write-only register used to force and clear
interrupts.
On-chip stacks preserve the processor status and are automatically 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 servicing 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 ADSP-2181 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
The ADSP-2181 processor has a low power feature that lets
the processor enter a very low power dormant state through
hardware or software control. Here is a brief list of powerdown features. For detailed information about the powerdown feature, refer to the ADSP-2100 Family User’s Manual,
Third Edition, “System Interface” chapter.
• 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
processor 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 4096
CLKIN cycles for the crystal oscillator to start and 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 powerdown.
• Power-down acknowledge pin indicates when the processor has entered power-down.
Idle
When the ADSP-2181 is in the Idle Mode, the processor
waits indefinitely in a low power state until an interrupt
occurs. When an unmasked interrupt occurs, it is serviced;
execution then continues with the instruction following the
IDLE instruction.
Slow Idle
The IDLE instruction is enhanced on the ADSP-2181 to let
the processor’s internal clock signal be slowed, further
reducing power consumption. The reduced clock frequency, a programmable fraction of the normal clock rate,
is specified by a selectable divisor given in the IDLE instruction. The format of the instruction is
IDLE (n);
where n = 16, 32, 64 or 128. This instruction keeps the
processor fully functional, but operating at the slower clock
rate. While it is in this state, the processor’s other internal
clock signals, such as SCLK, CLKOUT and timer clock,
are reduced by the same ratio. The default form of the
instruction, when no clock divisor is given, is the standard
IDLE instruction.
REV. D
–5–
ADSP-2181
CLKIN
CLKOUT
XTAL
DSP
When the IDLE (n) instruction is used, it effectively slows down
the processor’s internal clock and thus its response time to incoming interrupts. The one-cycle response time of the standard
idle state is increased by n, the clock divisor. When an enabled
interrupt is received, the ADSP-2181 will remain in the idle
state for up to a maximum of n processor cycles (n = 16, 32, 64
or 128) before resuming normal operation.
When the IDLE (n) instruction is used in systems that have an
externally generated serial clock (SCLK), the serial clock rate
may be faster than the processor’s reduced internal clock rate.
Under these conditions, interrupts must not be generated at a
faster rate than can be serviced, due to the additional time the
processor takes to come out of the idle state (a maximum of n
processor cycles).
SYSTEM INTERFACE
Figure 2 shows a typical basic system configuration with the
ADSP-2181, two serial devices, a byte-wide EPROM, and optional external program and data overlay memories. Programmable wait state generation allows the processor to connect
easily to slow peripheral devices. The ADSP-2181 also provides
four external interrupts and two serial ports or six external interrupts and one serial port.
1/2x CLOCK
OR
CRYSTAL
SERIAL
DEVICE
SERIAL
DEVICE
SYSTEM
INTERFACE
OR
mCONTROLLER
16
ADSP-2181
CLKIN
XTAL
FL0-2
PF0-7
IRQ2
IRQE
IRQL0
IRQL1
SPORT1
SCLK1
RFS1 OR IRQ0
TFS1 OR IRQ1
DT1 OR FO
DR1 OR FI
SPORT0
SCLK0
RFS0
TFS0
DT0
DR0
IDMA PORT
IRD
IWR
IS
IAL
IACK
IAD15-0
ADDR13-0
DATA23-0
BMS
WR
IOMS
PMS
DMS
CMS
BGH
PWD
PWDACK
RD
BR
BG
A
14
24
13-0
D
A0-A21
23-16
D
A
D
A
D
15-8
10-0
13-0
23-8
23-0
DATA
CS
ADDR
DATA
CS
ADDR
DATA
BYTE
MEMORY
I/O SPACE
(PERIPHERALS)
2048 LOCATIONS
OVERLAY
MEMORY
TWO 8K
PM SEGMENTS
TWO 8K
DM SEGMENTS
Figure 2. ADSP-2181 Basic System Configuration
Clock Signals
The ADSP-2181 can be clocked by either a crystal or a TTLcompatible clock signal.
The CLKIN input cannot be halted, changed during operation
or operated below the specified frequency during normal operation. The only exception is while the processor is in the powerdown state. For additional information, refer to Chapter 9,
ADSP-2100 Family User’s Manual, Third Edition, for detailed
information on this power-down feature.
If an external clock is used, it should be a TTL-compatible
signal running at half the instruction rate. The signal is connected to the processor’s CLKIN input. When an external clock
is used, the XTAL input must be left unconnected.
The ADSP-2181 uses an input clock with a frequency equal to
half the instruction rate; a 20.00 MHz input clock yields a 25 ns
processor cycle (which is equivalent to 40 MHz). Normally,
instructions are executed in a single processor cycle. All device
timing is relative to the internal instruction clock rate, which is
indicated by the CLKOUT signal when enabled.
Because the ADSP-2181 includes an on-chip oscillator circuit,
an external crystal may be used. The crystal should be connected
across the CLKIN and XTAL pins, with two capacitors connected
as shown in Figure 3. Capacitor values are dependent on crystal
type and should be specified by the crystal manufacturer. A
parallel-resonant, fundamental frequency, microprocessor-grade
crystal should be used.
A clock output (CLKOUT) signal is generated by the processor
at the processor’s cycle rate. This can be enabled and disabled
by the CLKODIS bit in the SPORT0 Autobuffer Control
Register.
Figure 3. External Crystal Connections
Reset
The RESET signal initiates a master reset of the ADSP-2181.
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 V
DD
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 minimum pulse width specification, t
RSP
.
The RESET input contains some hysteresis; however, if you use
an RC circuit to generate your RESET signal, the use of an
external Schmidt 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 (MMAP = 0), the
boot-loading sequence is performed. The first instruction is
fetched from on-chip program memory location 0x0000 once
boot loading completes.
–6–
REV. D
ADSP-2181
Memory Architecture
The ADSP-2181 provides a variety of memory and peripheral
interface options. The key functional groups are Program
Memory, Data Memory, Byte Memory and I/O.
Program Memory is a 24-bit-wide space for storing both
instruction opcodes and data. The ADSP-2181 has 16K 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. Both an instruction opcode and a data value
can be read from on-chip program memory in a single cycle.
Data Memory is a 16-bit-wide space used for the storage of
data variables and for memory-mapped control registers. The
ADSP-2181 has 16K words on Data Memory RAM on chip,
consisting of 16,352 user-accessible locations and 32 memorymapped registers. Support also exists for up to two 8K external
memory overlay spaces through the external data bus.
Byte Memory provides access to an 8-bit wide memory space
through the Byte DMA (BDMA) port. The Byte Memory interface provides access to 4 MBytes of memory by utilizing eight
data lines as additional address lines. This gives the BDMA Port
an effective 22-bit address range. On power-up, the DSP can
automatically load bootstrap code from byte memory.
I/O Space allows access to 2048 locations of 16-bit-wide data.
It is intended to be used to communicate with parallel peripheral devices such as data converters and external registers or
latches.
Program Memory
The ADSP-2181 contains a 16K × 24 on-chip program RAM.
The on-chip program memory is designed to allow up to two
accesses each cycle so that all operations can complete in a
single cycle. In addition, the ADSP-2181 allows the use of 8K
external memory overlays.
The program memory space organization is controlled by the
MMAP pin and the PMOVLAY register. Normally, the ADSP2181 is configured with MMAP = 0 and program memory organized as shown in Figure 4.
PROGRAM MEMORY
8K INTERNAL
(PMOVLAY = 0,
MMAP = 0)
OR
EXTERNAL 8K
(PMOVLAY = 1 or 2,
MMAP = 0)
8K INTERNAL
ADDRESS
0x3FFF
0x2000
0x1FFF
0x0000
Figure 4. Program Memory (MMAP = 0)
There are 16K words of memory accessible internally when the
PMOVLAY register is set to 0. When PMOVLAY is set to
something other than 0, external accesses occur at addresses
0x2000 through 0x3FFF. The external address is generated as
shown in Table II.
Table II.
PMOVLAY Memory A13 A12:0
0 Internal Not Applicable Not Applicable
1 External 0 13 LSBs of Address
Overlay 1 Between 0x2000
and 0x3FFF
2 External 1 13 LSBs of Address
Overlay 2 Between 0x2000
and 0x3FFF
This organization provides for two external 8K overlay segments
using only the normal 14 address bits. This allows for simple
program overlays using one of the two external segments in
place of the on-chip memory. Care must be taken in using this
overlay space in that the processor core (i.e., the sequencer)
does not take into account the PMOVLAY register value. For
example, if a loop operation was occurring on one of the external overlays and the program changes to another external overlay or internal memory, an incorrect loop operation could occur.
In addition, care must be taken in interrupt service routines as
the overlay registers are not automatically saved and restored on
the processor mode stack.
For ADSP-2100 Family compatibility, MMAP = 1 is allowed.
In this mode, booting is disabled and overlay memory is disabled (PMOVLAY must be 0). Figure 5 shows the memory map
in this configuration.
PROGRAM MEMORY ADDRESS
0x3FFF
INTERNAL 8K
(PMOVLAY = 0,
MMAP = 1)
0x2000
0x1FFF
8K EXTERNAL
0x0000
Figure 5. Program Memory (MMAP = 1)
Data Memory
The ADSP-2181 has 16,352 16-bit words of internal data
memory. In addition, the ADSP-2181 allows the use of 8K
external memory overlays. Figure 6 shows the organization of
the data memory.
DATA MEMORY
32 MEMORY–
MAPPED REGISTERS
INTERNAL
8160 WORDS
8K INTERNAL
(DMOVLAY = 0)
OR
EXTERNAL 8K
(DMOVLAY = 1, 2)
ADDRESS
0x3FFF
0x3FEO
0x3FDF
0x2000
0x1FFF
0x0000
Figure 6. Data Memory
REV. D
–7–
ADSP-2181
There are 16,352 words of memory accessible internally when
the DMOVLAY register is set to 0. When DMOVLAY is set to
something other than 0, external accesses occur at addresses
0x0000 through 0x1FFF. The external address is generated as
shown in Table III.
Table III.
DMOVLAY Memory A13 A12:0
0 Internal Not Applicable Not Applicable
1 External 0 13 LSBs of Address
Overlay 1 Between 0x0000
and 0x1FFF
2 External 1 13 LSBs of Address
Overlay 2 Between 0x0000
and 0x1FFF
This organization allows for two external 8K overlays using only
the normal 14 address bits.
All internal accesses complete in one cycle. Accesses to external
memory are timed using the wait states specified by the DWAIT
register.
I/O Space
The ADSP-2181 supports an additional external memory space
called I/O space. This space is designed to support simple connections to peripherals or to bus interface ASIC data registers.
I/O space supports 2048 locations. The lower eleven bits of the
external address bus are used; the upper three bits are undefined. Two instructions were added to the core ADSP-2100
Family instruction set to read from and write to I/O memory
space. The I/O space also has four dedicated 3-bit wait state
registers, IOWAIT0-3, which specify up to seven wait states to
be automatically generated for each of four regions. The wait
states act on address ranges as shown in Table IV.
Table IV.
Address Range Wait State Register
0x000–0x1FF IOWAIT0
0x200–0x3FF IOWAIT1
0x400–0x5FF IOWAIT2
0x600–0x7FF IOWAIT3
Composite Memory Select (CMS)
The ADSP-2181 has a programmable memory select signal that
is useful for generating memory select signals for memories
mapped to more than one space. The CMS signal is generated
to have the same timing as each of the individual memory select
signals (PMS, DMS, BMS, IOMS) but can combine their
functionality.
When set, each bit in the CMSSEL register, causes the CMS
signal to be asserted when the selected memory select is asserted. For example, to use a 32K word memory to act as both
program and data memory, set the PMS and DMS bits in the
CMSSEL register and use the CMS pin to drive the chip select
of the memory; use either DMS or PMS as the additional
address bit.
The CMS pin functions like the other memory select signals,
with the same timing and bus request logic. A 1 in the enable bit
causes the assertion of the CMS signal at the same time as the
selected memory select signal. All enable bits, except the BMS
bit, default to 1 at reset.
Byte Memory
The byte memory space is a bidirectional, 8-bit-wide, external
memory space used to store programs and data. Byte memory is
accessed using the BDMA feature. The byte memory space
consists of 256 pages, each of which is 16K × 8.
The byte memory space on the ADSP-2181 supports read and
write operations as well as four different data formats. The byte
memory uses data bits 15:8 for data. The byte memory uses
data bits 23:16 and address bits 13:0 to create a 22-bit address.
This allows up to a 4 meg × 8 (32 megabit) ROM or RAM to be
used without glue logic. All byte memory accesses are timed by
the BMWAIT register.
Byte Memory DMA (BDMA)
The Byte memory DMA controller allows loading and storing of
program instructions and data using the byte memory space.
The BDMA circuit is able to access the byte memory space
while the processor is operating normally, and steals only one
DSP cycle per 8-, 16- or 24-bit word transferred.
The BDMA circuit supports four different data formats which
are selected by the BTYPE register field. The appropriate number of 8-bit accesses are done from the byte memory space to
build the word size selected. Table V shows the data formats
supported by the BDMA circuit.
Table V.
Internal
BTYPE Memory Space Word Size Alignment
00 Program Memory 24 Full Word
01 Data Memory 16 Full Word
10 Data Memory 8 MSBs
11 Data Memory 8 LSBs
Unused bits in the 8-bit data memory formats are filled with 0s.
The BIAD register field is used to specify the starting address
for the on-chip memory involved with the transfer. The 14-bit
BEAD register specifies the starting address for the external byte
memory space. The 8-bit BMPAGE register specifies the starting page for the external byte memory space. The BDIR register
field selects the direction of the transfer. Finally the 14-bit
BWCOUNT register specifies the number of DSP words to
transfer and initiates the BDMA circuit transfers.
BDMA accesses can cross page boundaries during sequential
addressing. A BDMA interrupt is generated on the completion
of the number of transfers specified by the BWCOUNT register.
The BWCOUNT register is updated after each transfer so it can
be used to check the status of the transfers. When it reaches
zero, the transfers have finished and a BDMA interrupt is generated. The BMPAGE and BEAD registers must not be accessed
by the DSP during BDMA operations.
The source or destination of a BDMA transfer will always be
on-chip program or data memory, regardless of the values of
MMAP, PMOVLAY or DMOVLAY.
–8–
REV. D
ADSP-2181
When the BWCOUNT register is written with a nonzero value,
the BDMA circuit starts executing byte memory accesses with
wait states set by BMWAIT. These accesses continue until the
count reaches zero. When enough accesses have occurred to
create a destination word, it is transferred to or from on-chip
memory. The transfer takes one DSP cycle. DSP accesses to
external memory have priority over BDMA byte memory accesses.
The BDMA Context Reset bit (BCR) controls whether the
processor is held off while the BDMA accesses are occurring.
Setting the BCR bit to 0 allows the processor to continue operations. Setting the BCR bit to 1 causes the processor to stop
execution while the BDMA accesses are occurring, to clear the
context of the processor and start execution at address 0 when
the BDMA accesses have completed.
Internal Memory DMA Port (IDMA Port)
The IDMA Port provides an efficient means of communication
between a host system and the ADSP-2181. The port is used to
access the on-chip program memory and data memory of the
DSP with only one DSP cycle per word overhead. The IDMA
port cannot, however, be used to write to the DSP’s memorymapped control registers.
The IDMA port has a 16-bit multiplexed address and data bus
and supports 24-bit program memory. The IDMA port is
completely asynchronous and can be written to while the
ADSP-2181 is operating at full speed.
The DSP memory address is latched and then automatically
incremented after each IDMA transaction. An external device
can therefore access a block of sequentially addressed memory
by specifying only the starting address of the block. This increases throughput as the address does not have to be sent for
each memory access.
IDMA Port access occurs in two phases. The first is the IDMA
Address Latch cycle. When the acknowledge is asserted, a 14bit address and 1-bit destination type can be driven onto the bus
by an external device. The address specifies an on-chip memory
location; the destination type specifies whether it is a DM or
PM access. The falling edge of the address latch signal latches
this value into the IDMAA register.
Once the address is stored, data can either be read from or
written to the ADSP-2181’s on-chip memory. Asserting the
select line (IS) and the appropriate read or write line (IRD and
IWR respectively) signals the ADSP-2181 that a particular
transaction is required. In either case, there is a one-processorcycle delay for synchronization. The memory access consumes
one additional processor cycle.
Once an access has occurred, the latched address is automatically incremented and another access can occur.
Through the IDMAA register, the DSP can also specify the
starting address and data format for DMA operation.
Bootstrap Loading (Booting)
The ADSP-2181 has two mechanisms to allow automatic loading of the on-chip program memory after reset. The method for
booting after reset is controlled by the MMAP and BMODE
pins as shown in Table VI.
Table VI. Boot Summary Table
MMAP BMODE Booting Method
0 0 BDMA feature is used in default mode
to load the first 32 program memory
words from the byte memory space.
Program execution is held off until all
32 words have been loaded.
0 1 IDMA feature is used to load any inter-
nal memory as desired. Program execution is held off until internal program
memory location 0 is written to.
1 X Bootstrap features disabled. Program
execution immediately starts from
location 0.
BDMA Booting
When the BMODE and MMAP pins specify BDMA booting
(MMAP = 0, BMODE = 0), the ADSP-2181 initiates a BDMA
boot sequence when reset is released. The BDMA interface is
set up during reset to the following defaults when BDMA booting is specified: the BDIR, BMPAGE, BIAD and BEAD registers are set to 0, the BTYPE register is set to 0 to specify
program memory 24 bit words, and the BWCOUNT register is
set to 32. This causes 32 words of on-chip program memory to
be loaded from byte memory. These 32 words are used to set up
the BDMA to load in the remaining program code. The BCR
bit is also set to 1, which causes program execution to be held
off until all 32 words are loaded into on-chip program memory.
Execution then begins at address 0.
The ADSP-2100 Family Development Software (Revision 5.02
and later) fully supports the BDMA booting feature and can
generate byte memory space compatible boot code.
The IDLE instruction can also be used to allow the processor to
hold off execution while booting continues through the BDMA
interface.
IDMA Booting
The ADSP-2181 can also boot programs through its Internal
DMA port. If BMODE = 1 and MMAP = 0, the ADSP-2181
boots from the IDMA port. IDMA feature can load as much onchip memory as desired. Program execution is held off until onchip program memory location 0 is written to.
The ADSP-2100 Family Development Software (Revision 5.02
and later) can generate IDMA compatible boot code.
Bus Request and Bus Grant
The ADSP-2181 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 (BR) signal. If the
ADSP-2181 is not performing an external memory access, then
it responds to the active BR input in the following processor
cycle by:
• three-stating the data and address buses and the PMS, DMS,
BMS, CMS, IOMS, RD, WR output drivers,
• asserting the bus grant (BG) signal, and
• halting program execution.
REV. D
–9–
ADSP-2181
12
3
4
56
78
910
11 12
13 14
GND
KEY (NO PIN)
RESET
BR
BG
TOP VIEW
EBG
EBR
ELOUT
EE
EINT
ELIN
ECLK
EMS
ERESET
If Go Mode is enabled, the ADSP-2181 will not halt program
execution until it encounters an instruction that requires an
external memory access.
If the ADSP-2181 is performing an external memory access
when the external device asserts the BR signal, then it will not
three-state the memory interfaces or assert the BG signal until
the processor cycle after the access completes. 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, reenables the output drivers and continues program
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.
The BGH pin is asserted when the ADSP-2181 is ready to
execute an instruction, but is stopped because the external bus
is already granted to another device. The other device can release the bus by deasserting bus request. Once the bus is released, the ADSP-2181 deasserts BG and BGH and executes
the external memory access.
Flag I/O Pins
The ADSP-2181 has eight general purpose programmable input/output flag pins. They are controlled by two memory
mapped registers. The PFTYPE register determines the direction, 1 = output and 0 = input. The PFDATA register is used to
read and write the values on the pins. Data being read from a
pin configured as an input is synchronized to the ADSP-2181’s
clock. Bits that are programmed as outputs will read the value
being output. The PF pins default to input during reset.
In addition to the programmable flags, the ADSP-2181 has
five fixed-mode flags, FLAG_IN, FLAG_OUT, FL0, FL1 and
FL2. FL0-FL2 are dedicated output flags. FLAG_IN and
FLAG_OUT are available as an alternate configuration of
SPORT1.
INSTRUCTION SET DESCRIPTION
The ADSP-2181 assembly language instruction set has an
algebraic syntax that was designed for ease of coding and readability. The assembly language, which takes full advantage of the
processor’s unique architecture, offers the following benefits:
• The algebraic syntax eliminates the need to remember cryptic
• Every instruction assembles into a single, 24-bit word that can
• The syntax is a superset ADSP-2100 Family assembly lan-
• Sixteen condition codes are available. For conditional jump,
assembler mnemonics. For example, a typical arithmetic add
instruction, such as AR = AX0 + AY0, resembles a simple
equation.
execute in a single instruction cycle.
guage and is completely source and object code compatible
with other family members. Programs may need to be relocated to utilize on-chip memory and conform to the ADSP2181’s interrupt vector and reset vector map.
call, return or arithmetic instructions, the condition can be
checked and the operation executed in the same instruction
cycle.
–10–
• Multifunction instructions allow parallel execution of an
arithmetic instruction with up to two fetches or one write to
processor memory space during a single instruction cycle.
DESIGNING AN EZ-ICE-COMPATIBLE SYSTEM
The ADSP-2181 has on-chip emulation support and an ICEPort, a special set of pins that interface to the EZ-ICE. These
features allow in-circuit emulation without replacing the target
system processor by using only a 14-pin connection from the
target system to the EZ-ICE. Target systems must have a 14-pin
connector to accept the EZ-ICE
’s in-circuit probe, a 14-pin plug.
The ICE-Port interface consists of the following ADSP-2181 pins:
EBR EMS ELIN
EBG EINT ELOUT
ERESET ECLK EE
These ADSP-2181 pins must be connected only to the EZ-ICE
connector in the target system. These pins have no function
except during emulation, and do not require pull-up or pulldown resistors. The traces for these signals between the ADSP2181 and the connector must be kept as short as possible, no
longer than three inches.
The following pins are also used by the EZ-ICE:
BR BG
GND RESET
The EZ-ICE
uses the EE (emulator enable) signal to take control of the ADSP-2181 in the target system. This causes the
processor to use its ERESET, EBR and EBG pins instead of the
RESET, BR and BG pins. The BG output is three-stated.
These signals do not need to be jumper-isolated in your system.
The EZ-ICE
connects to the target system via a ribbon cable
and a 14-pin female plug. The ribbon cable is 10 inches in
length with one end fixed to the EZ-ICE. The female plug is
plugged onto the 14-pin connector (a pin strip header) on the
target board.
Target Board Connector for EZ-ICE Probe
The EZ-ICE connector (a standard pin strip header) is shown in
Figure 7. You must add this connector to your target board
design if you intend to use the EZ-ICE. Be sure to allow enough
room in your system to fit the EZ-ICE
probe onto the 14-pin
connector.
Figure 7. Target Board Connector for EZ-ICE
REV. D
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