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From: EDN - 05/19/1995 - page 24
By: John Murray,
American Microsystems, Inc.
Automobile racing is a harsh environment for electronic
systems. On-board electronics systems must be small, light, fast and provide
considerable functionality,. They must also be able to withstand severe
physical stress caused by heat, G-force, vibration and road grime. At the same
time, they must provide performance and flexibility so that race teams can
effectively implement the latest control algorithms and data acquisition
strategies.
Ford Motor Company's Indy car and Formula One programs
now employ a novel system that is helping them fine-tune the performance of
their cars' electronic applications. This system, the Formula Data Logger 32,
consists of a single-board computer (SBC) that uses a Forth microprocessor, the
SC32 from Silicon Composers of Mountain View, CA, which was developed at the
Applied Physics Lab of The Johns Hopkins University. The system fits the entire
CPU, I/O, and control and communication hardware into a dual-PCMCIA-sized
enclosure that takes up very little space, requires minimal power, and adds
little weight. In addition, two PCMCIA slots house the SBC's program and data
storage subsystem.
The SBC performs communications control and data logging
for the Indy car, and is connected to the car's other electronics systems over
Ford's onboard bus. During each race the SBC monitors the actions and
communications among the car's other electrical subsystems, stores the results,
and selects critical data to transmit to the pit crew vir telemetry.
Afterwards, Ford Electronics engineers can download all remaining results
through a serial link and analyze them on a laptop computer. Programming
changes can be subsequently loaded back into the race car to improve its next
performance on the track.
Compact Performance
To meet the extremes of the automotive racing
environment, Ford chose the SC32, a high-speed, general purpose embedded
microcontroller which uses a 32-bit bus architecture. The SC32 funtions as a
data logger, acquiring attributes about the car during a race, and then stores
them into either SRAM or flash memory. The SBC can analyze and process this
data as well, making decisions about what information to send to the team in
the pit.
The SBC compares very favorably with previous onboard
electronics systems used by Ford for its Indy and Formula One programs. These
systems were composed of three boards, each one larger than the current
dual-PCMCIA-sized board.
In addition to the SBC's small size, the computer
implements functions in very little code and executes them very quickly. This
is accomplished by the SC32 microcontroller whic implements the Forth language
model in hardware. As a result, the SC32 requires approximately one fourth the
memory space of other languages running on other microprocessors. As an added
benefit, application development time and testing on the SC32 is reduced by
about fifty percent of the time needed using a different microprocessor and
langauge because Forth allows engineers to develop their applications
interactively.
To speed the SC32's processing time, the Forth language
use two stacks, one for data and one for instructions. These stacks are
implemented on the microprocessor's hardware, similar to a cache, rather than
in memory. As a result, the SC32 can deliver up to 32 MIPS of processing power
by loading instructions and data rapidly into memory.
The Ford engineers are able to develop the application
software for the SBC themselves, allowing them to quickly modify the Indy and
Formula One electronic systems. The SC32 comes complete with a software
developmentsystem. This consists of an optimizing cross compiler with debugging
software and utilities. A text editor is included, with pull-down menus, help
screens and "load and run from editor" capability. The Ford engineers can write
applications for the SC32 system interactively on the SC32 itself. This reduces
the time and expense of writing the applications on a separate personal
computer or workstation and then downloading the code to work with the SC32.
The engineers accomplish this by hooking up an SBC identical tot he one in the
Indy and Formula One cars to a termina. Code written on the terminal can then
be uploaded to the system by serial link.
PCMCIA Storage Adds Flexibility
In addition to the SC32, the SBC uses two PCMCIA slots
to house its storage subsystem. These two slots can house either flash memory
or battery-backed SRAM cards. The PCMCIA card, in effect an MCM with a
standardized connector, is a plug and play system. This menas Ford can easily
upgrade the system by plugging new PCMCIA cards into the SBC data logger.
American Microsystems, Inc.'s (AMI) ASIS (Application Specific Integrated
Systesm) Division, who supplied the PCMCIA cards, initially installed two 2MB
SRAM cards into the system. During racing season, the Ford engineers desired to
make modifications to the cards, including upgrading to more memory. AMI
supplied quick-turns on the cards from week to week, allowing Ford to upgrade
to 4 MB per card.
One other modification made by AMI, was the removal of
the PCMCIA card's rechargable battery. The purpose of this battery was to
supply secondary back-up power to the PCMCIA cards whendetacthed from the
microprocessor. Ford, however, did not require the battery since they
downloaded date through a serial hook up, as well as through telemetry, instead
of by removal of the PCMCIA cards after each race. Since the battery added
extra weight, they asked AMI to remove it.
Since flash cards are firmware, and SRAM is a fast
read/write system, the Ford Formula SBC is able to quickly boot up from either
type of PCMCIA card. The Ford Electronics engineers use the two cards
concurrently for fast 32-bit access. The system boots from the beginning of the
cards. The remaining RAM is used to hold configuration data and for data
logging during the race. One reason Ford chose AMI's PCMCIA cards is because
they are rigid and self-contained, allowing them to withstand the rigors of the
automotive environment better than floppy diskettes and CDs, whic are easily
damaged by petrochemicals and high temperatures.
From Racetrack to Highway
The communications and data logging system has helped
the Ford team to analyze the performance of the electronics in their cars more
quickly than before, and to modify them during the course of the racing season.
This is part of the successful overall strategy used by Ford Benneton racing
team with driver Michael Schmacher, the 1994 Formula One World Champion. But
Ford realizes an added benefit from the program - the experience of the
automaker has acquired in the development of computer systems to control engine
functions. In the future, Foird hopes to use the information gathered from the
Formula One and Indy programs to help design consumer vehicles. Such designs
might help customize engines across different automobile lines for improved
perfromance and mileage. Or they might assist in making car engines better at
facing the dangers of the ordinary highway, as well as the dangers of the race
track. It is these types of innovations and performance improvements that are
the real reasons Ford goes racing.
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Performance data
is downloaded and programming changes are made between practice sessions
through a serial link located directly in front of the engine (above EDS
logo).
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Ford's Formula Data Logger 32
fits the entire CPU, I/O, and communication hardware into a dual-PCMCIA-sized
enclosure.
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Ford Electroncis
engineers analyze the data transmitted by the Formula Data Logger 32 installed
in Robbie Gordon's Indy car during practice at Pennsylvania's Nazareth
Speedway.
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