ADSP-21020
REV. C
–2–
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Instruction Cache
The ADSP-21020 includes a high performance instruction
cache that enables three-bus operation for fetching an
instruction and two data values. The cache is selective—only
the instructions whose fetches conflict with program memory
data accesses are cached. This allows full-speed execution
of core, looped operations such as digital filter multiply-
accumulates and FFT butterfly processing.
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Hardware Circular Buffers
The ADSP-21020 provides hardware to implement circular
buffers in memory, which are common in digital filters and
Fourier transform implementations. It handles address
pointer wraparound, reducing overhead (thereby increasing
performance) and simplifying implementation. Circular
buffers can start and end at any location.
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Flexible Instruction Set
The ADSP-21020’s 48-bit instruction word accommodates a
variety of parallel operations, for concise programming. For
example, the ADSP-21020 can conditionally execute a
multiply, an add, a subtract and a branch in a single
instruction.
DEVELOPMENT SYSTEM
The ADSP-21020 is supported with a complete set of software
and hardware development tools. The ADSP-21000 Family
Development System includes development software, an
evaluation board and an in-circuit emulator.
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Assembler
Creates relocatable, COFF (Common Object File Format)
object files from ADSP-21xxx assembly source code. It
accepts standard C preprocessor directives for conditional
assembly and macro processing. The algebraic syntax of the
ADSP-21xxx assembly language facilitates coding and
debugging of DSP algorithms.
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Linker/Librarian
The Linker processes separately assembled object files and
library files to create a single executable program. It assigns
memory locations to code and to data in accordance with a
user-defined architecture file that describes the memory and
I/O configuration of the target system. The Librarian allows
you to group frequently used object files into a single library
file that can be linked with your main program.
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Simulator
The Simulator performs interactive, instruction-level
simulation of ADSP-21xxx code within the hardware
configuration described by a system architecture file. It flags
illegal operations and supports full symbolic disassembly. It
provides an easy-to-use, window oriented, graphical user
interface that is identical to the one used by the ADSP-21020
EZ-ICE Emulator. Commands are accessed from pull-down
menus with a mouse.
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PROM Splitter
Formats an executable file into files that can be used with an
industry-standard PROM programmer.
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C Compiler and Runtime Library
The C Compiler complies with ANSI specifications. It takes
advantage of the ADSP-21020’s high-level language architec-
tural features and incorporates optimizing algorithms to speed
up the execution of code. It includes an extensive runtime
library with over 100 standard and DSP-specific functions.
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C Source Level Debugger
A full-featured C source level debugger that works with the
simulator or EZ-ICE emulator to allow debugging of
assembler source, C source, or mixed assembler and C.
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Numerical C Compiler
Supports ANSI Standard (X3J11.1) Numerical C as defined
by the Numeric C Extensions Group. The compiler accepts C
source input containing Numerical C extensions for array
selection, vector math operations, complex data types,
circular pointers, and variably dimensioned arrays, and
outputs ADSP-21xxx assembly language source code.
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ADSP-21020 EZ-LAB®
Evaluation Board
The EZ-LAB Evaluation Board is a general-purpose, stand-
alone ADSP-21020 system that includes 32K words of
program memory and 32K words of data memory as well as
analog I/O. A PC RS-232 download path enables the user to
download and run programs directly on the EZ-LAB. In
addition, it may be used in conjunction with the EZ-ICE
Emulator to provide a powerful software debug environment.
•
ADSP-21020 EZ-ICE® Emulator
This in-circuit emulator provides the system designer with a
PC-based development environment that allows nonintrusive
access to the ADSP-21020’s internal registers through the
processor’s 5-pin JTAG Test Access Port. This use of on-chip
emulation circuitry enables reliable, full-speed performance in
any target. The emulator uses the same graphical user inter-
face as the ADSP-21020 Simulator, allowing an easy tran-
sition from software to hardware debug. (See “Target System
Requirements for Use of EZ-ICE Emulator” on page 27.)
ADDITIONAL INFORMATION
This data sheet provides a general overview of ADSP-21020
functionality. For additional information on the architecture and
instruction set of the processor, refer to the ADSP-21020 User’s
Manual. For development system and programming reference
information, refer to the ADSP-21000 Family Development
Software Manuals and the ADSP-21020 Programmer’s Quick
Reference. Applications code listings and benchmarks for key
DSP algorithms are available on the DSP Applications BBS; call
(617) 461-4258, 8 data bits, no parity, 1 stop bit, 300/1200/
2400/9600 baud.
ARCHITECTURE OVERVIEW
Figure 1 shows a block diagram of the ADSP-21020. The
processor features:
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Three Computation Units (ALU, Multiplier, and Shifter)
with a Shared Data Register File
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Two Data Address Generators (DAG 1, DAG 2)
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Program Sequencer with Instruction Cache
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32-Bit Timer
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Memory Buses and Interface
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JTAG Test Access Port and On-Chip Emulation Support
Computation Units
The ADSP-21020 contains three independent computation
units: an ALU, a multiplier with fixed-point accumulator, and a
shifter. In order to meet a wide variety of processing needs, the
computation units process data in three formats: 32-bit
fixed-point, 32-bit floating-point and 40-bit floating-point. The
floating-point operations are single-precision IEEE-compatible
(IEEE Standard 754/854). The 32-bit floating-point format is
EZ-LAB and EZ-ICE are registered trademarks of Analog Devices, Inc.
