Specification • While no specific node-to-node interconnection method is specified in JAS it is highly recommended that the nodes make use of a standards-based chassis and backplane. SpaceVPX is similar to VPX but intended for space applications. [Placeholder: There may be sub-specs we can reference here, similar to the subspecs for VITA...
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Space Wire
Specification • SpaceWire is a full-duplex, point-to-point, serial data communications protocol in which the data is encoded on two differential signal pairs in each direction. This is the preferred JAS communication protocol for data rate below 200 Mbps. The electrical specifications for SpaceWire communications are described in the European Cooperation for Space...
SpaceWire
Specification • The figure below defines the format of the SpaceWire packet. Following sections will discuss the details of SpaceWire Addressing, Protocol Identifiers, and the various protocols that have been developed using SpaceWire for JAS. SpaceWire Packet
SpaceWire Addressing
Specification • SpaceWire addresses shall follow the allowed allocation defined in the SpaceWire standard. Only logical addresses will be used for router and endpoint addresses which means they must be in the range of 0x20-0xFE. JAS applications shall use SpaceWire regional addressing in conjunction with header deletion within the SpaceWire routers. Two...
SpaceWire Interconnect
Profile • SpaceWire is a communication network designed to connect sensors, processing units, memory devices and telemetry/telecommand subsystems together within a spacecraft. It provides moderate-rate (2 to 200 Mbps), bi-directional, full-duplex, data links. Application, control, and time information is sent along a SpaceWire link in discrete packets. A SpaceWire network is comprised...
SpaceWire Logical
Profile • The SpaceWire standard defines packets and protocol identifiers. The SpaceWire Logical Layer has the flexibility to utilize standard or customized protocols. There are two classes of protocols available to JAS applications: Memory access protocols – access and control memory devices that are located on remote nodes within a network Messaging...
SpaceWire Physical
Profile • JAS based systems will follow the SpaceWire standard for the physical characteristics. The details of the JAS-based implementation of the SpaceWire physical layer are found in the Electrical Specification.
SpaceWire Protocol Identifiers
Specification • The standard reserves protocol identifiers in the range of 1 to 239. Protocol identifiers in the range of 240-255 can be assigned by projects. The protocol identifiers ranging from 240-250 shall be reserved for JAS protocols. A list of the protocols used by JAS is shown in the table below....
SpaceWire Transport
Profile • The Transport Layer routes messages from one end-point processing element to another through switch processing elements. The following sections describe the various elements that define the SpaceWire Transport Layer.
Strength Qualification
Specification • The JAS mechanical structure design shall possess sufficient strength and rigidity to withstand environmental conditions defined in this document. Load Conditions
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