Use of Real-Time Composer™ Software in the OCD System
The JPL Optical Comm Group uses Real-Time Composer™ software to assist in the development and
maintenance of their prototype laser communication systems, or
"Optical Communication Demo" (OCD) systems.
During OCD system system design and code development cycles,
the Real-Time Composer™ and
DSPower-Real Time Code Generator (RTCG) software packages
are used. The Real-Time Composer™ provides an integrated
visual environment, including code flow diagram and signal flow diagram, and C
and asm. source code editing. The RTCG provides a visual
IDE to control the DSP vendor tools (C compiler, assembler, and linker)
needed to create executable code to run on the SigC44 board.
Note that in the OCD system signal and code flow diagrams shown at left, code constructs
such as case statement, while-loop, code blocks, etc. are shown in yellow, and
connected by red lines, which are called "flow control" lines. By contrast, function and
display/instrument blocks are connected by blue lines, which are called "data
flow" lines. Note that function blocks may also have explicit flow control
connections (such as in ambiguous cases like feedback), but in general the
DSPower system resolves program sequence by traversing data flow lines to find
input/output dependencies.
When the developer clicks on "Run" or "Make", the Real-Time Composer™ code generator combines signal
flow, code flow, and C/asm source code files and generates complete source code for
the project, including dependency checks. The Real-Time Composer™ visual IDE then controls the
DSP vendor tools transparently, in the background. All compiler and other
tool settings can be set using dialog boxes and
other visual project aides. The visual
IDE takes these settings and generates required auxilliary files such as linker
command files and memory-map definitions, feeds the newly generated source code to
the DSP vendor tools, and reports back error messages. By combining
the visual IDE with signal and code flow diagram editors, C/asm source code editor,
and real-time debug ability, the Real-Time Composer™ environment effectively creates a fully
integrated development environment for development and test of DSP code.
The Real-Time Composer™ software includes a "Real-Time Target Setup"
dialog box, from which any of the supported DSP hardware
types can be selected. From the choice of hardware (board), the Real-Time Composer™ system
automatically figures out the type of DSP device, the type of compiler tools needed,
source and include file extensions, and more. From the user's perspective, this
allows the choice of DSP board (and by extension, DSP device) to be abstracted to
a large extent. It also allows different projects to be created which
use the same source code and signal/code flow diagrams, but are configured to generate
code for different hardware. For example, in the OCD system, one project is used
to maintain a lab demo using an Ariel DSP-C40 board, and another is used to
maintain a field demo using the SigC44 board.
During OCD system code test and debug phases, the DirectDSP
software is used to interface GUI control panels to specific symbols (e.g.
variables and data buffers) inside the DSP C/asm code, and also to provide debug
capability, such as "real-time probe points". The OCD
control panel includes a toolbar which sends commands to the DSP code running on
the SigC44, as the code runs (without stopping the processor). Inside the toolbar,
individual buttons, knobs, and dials are "tied" to, or associated with, symbols
declared in C/asm source code. When the OCD operator clicks on these items,
commands are sent directly to the appropriate items in the DSP code.
For debug purposes, developers have access to a variety of probe points which
can show intermediate results of buffers, arrays, variables, flags, etc.
defined in the C/asm source code. Probe points offer a real-time, instantaneous
look at these symbols while code is running on the DSP, without stopping the
processor. Probe points available in the Real-Time Composer™ software include waveform
display, text read-out in various formats (floating-point, hex, decimal, etc),
meters, and gauge. Click here to see examples
of probe points in a Real-Time Composer™ debug diagram.
For More Information About Optical Communication...
For more information on Optical Communication Systems at Jet Propulsion
Laboratories (JPL), please send mail to:
Dr. Lesh is the overall Optical Comm Group (OCG) director at JPL; he is an
optical communication expert and long-time advocate, and is well-known and
respected in the space exploration community. Dr. Hemmati is the main
contact for Optical Communication systems and customer opportunities. Drs.
Muthu Jeganathan and Steve Monacos are both experts in optical communication
systems as well as other communication systems. Angel Portillo is an
outstanding young engineer recently graduated from the top-notch Electrical
Engineering program at Univ of Texas-El Paso, who is responsible for optical
communication system implementation, including DSP system software and
electronics.
Angel uses the Real-Time Composer™ and
DSPower-Real-Time Code Generator
software packages from Signalogic to develop and maintain the
complex DSP C/asm code which runs on the SigC44 boards. See above sections
Use of SigC44 DSP Board in the OCD System, and
Use of Real-Time Composer™ Software in the OCD System, for details
about how Signalogic tools are used by the OCG group.
