NASA STTR 2001-II Solicitation


RESEARCH TOPIC: 04-Launch and Payload Processing Systems
PROPOSAL TITLE: Utilizing MIL-STD-1553B Digital Data Bus Devices Across an IEEE-1394A Serial Bus

NAME: SEAKR Engineering, Inc NAME: Jet Propulsion Laboratory
ADDRESS: 6221 S. Racine Circle ADDRESS: 4800 Oak Grove Drive
CITY: Centennial CITY: Pasadena
STATE/ZIP:CO   80111 -6427 STATE/ZIP:CA   91109 -8099
PHONE: (303 ) 790 -8499 PHONE: (818 ) 354 -8659

 Dr. Savio Chau

The MIL-STD-1553B Bus is a widely supported data bus for avionics applications and compatible with most of the avionics equipment. However, its low data rate (1 Mbps) and command-response architecture are not suitable for many modern applications such as on-board autonomy. Therefore, the avionics industry recently has been interested in adopting the IEEE 1394A Bus as the next generation avionics bus. The IEEE 1394A Bus has a minimum bandwidth of 100 Mbps, which is two orders of magnitude faster than the 1553B Bus. In addition, its sophisticated protocol and multi-master capability can support distributed processing in advanced applications. One major obstacle in adopting the IEEE 1394A Bus is its compatibility with heritage equipment that is mostly compatible only with the 1553B Bus. It might take many years and large investments for the aerospace industry to convert all 1553B based equipment to the IEEE 1394A Bus.
The objective of this task is to solidify the IEEE-1394A standard in spacecraft engineering by providing backward compatibility with MIL-STD-1553B. This backward compatibility allows heterogeneous communications between the IEEE-1394A and MIL-STD-1553B buses, so that both heritage and modern components can share a common bus architecture. Hence, this backward compatibility would shorten the time to acceptance of the IEEE 1394A Bus.
In Phase I of this STTR, the functional requirements of the bridge and formats of the embedded commands have been defined. A software testbed has also been successfully implemented to demonstrate the read and write commands. In Phase II, a single board level implementation of the bridge will be designed, built and evaluated. This will provide the basis for further integration and miniaturization in a potential Phase III.

Many future NASA flight projects and commercial spacecraft, are considering the IEEE 1394 Bus as their baseline. These projects include the Mars Science Laboratory (MSL), the Europa Orbiter, and the next generation weather satellite program NPOESS. The science objectives of these missions require advanced application software such as on-board autonomy, real time hazard avoidance and precise landing. These advanced application software demand processing capability beyond current flight-qualified processors (e.g. the Rad 750). Therefore, distributed multiprocessor architectures have to be developed to support these applications.

In contrast, many instruments such as the inertial measure units (IMU) and the Small Deep Space Transponder (SDST) that are being considered by these missions, are compatible only with the MIL-STD-1553B bus. In the avionics industry, as the next generation unmanned aircraft are developed with more sophisticated processing, they will require a more advanced bus architecture, but they still use many heritage sensors.

With this bridge, much heritage equipment can be made compatible with the IEEE 1394 Bus without redesign.

Form Printed on 11-07-02 15:55