Adaptation Layer for SpaceWire Plug-and-Play Protocols, 10-R8216
Principal Investigators
Paul Wood
Allison Bertrand
Inclusive Dates: 04/01/11 – Current
Background — Network solutions to support rapid development and deployment of space assets and satellite plug and play (PnP) concepts are currently of great interest to the space community. The European Space Agency (ESA) and U.S. Air Force Research Laboratory (AFRL) both have PnP initiatives. Although gaining some ground, network-enabled devices such as sensors are currently rare. Network attached storage (NAS) is an anticipated early need for SpaceWire (SpW) PnP.
Approach — An adaptation layer suitable to allow an application program to operate in a network conforming to either PnP standard is the main goal of this project. A simulated NAS is being used as a challenge task to accomplish proof of concept for the adaptation layer. To this end, an SpW network consisting of a simulated producer, consumer and NAS device will be assembled. In this context, relevant elements of the two competing PnP protocols (ESA and AFRL) will be evaluated.
Accomplishments — A hardware setup consisting of the following was assembled: three Pentium® 4 computers running a Linux Ubuntu distribution, three SpaceWire cards, four SpaceWire cables and two SpaceWire routers. An additional computer connects the routers over a universal serial bus (USB) and is used to configure the SpW routers and monitor the SpW network.
SwRI researchers analyzed the protocols described in the Spacecraft Onboard Interface Services (SOIS) and the Space Plug-and-Play Architecture (SPA) standards produced by ESA and AFRL, respectively. The SPA standards are much more mature than those of the SOIS. The SPA has undergone more iterations of refinement and has a second generation software reference implementation nearing completion. No reference implementation is available for the SOIS.
The project team acquired a current copy of the SPA reference implementation and was able to host it on the development environment. The reference implementation was modified to use the SpW driver to communicate over the SpW hardware. The existing SpW interface driver was modified to provide necessary support for the SPA Services Manager (SSM). Researchers defined an Application Program Interface (API) for the adaptation layer and developed the simulated producer and consumer applications and the simulated NAS. These components are communicating in a proof-of-concept configuration that uses an implementation of the adaptation layer API to provide access to the underlying SSM.
