Specification • The rear transition module (RTM) of the VPX standard is a plug-in module at the back of the circuit card chassis that is in line with the front plug-in module or node. The backplane connectors on the RTM are the same as those used on the plug-in nodes. Also, as...
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Receive TEP Operations
Specification • A receive TEP shall not send DATA or CONTROL packets. It may only send ACK packets. Sliding Window The receive TEP shall maintain a sliding window, which is a range of consecutive sequence numbers that is used to determine whether each received DATA packet will be accepted or discarded. The...
Reconfigurable Processing Profile
Other • The Reconfigurable Processing (RP) profile defines a high-performance processing solution suitable for constructing nodes for mission data processing, sensor interfaces, and other applications requiring high-bandwidth processing and communications. Nodes based on the RP profile work alongside other nodes within the JAS architecture. The SMAC Profile and the Communication Profile implement...
Reconfigurable Processing Profile
Profile • The RP profile defines a high-performance processing solution suitable for constructing nodes for mission data processing, sensor interfaces, and other applications requiring high-bandwidth processing and communications. The RP profile works alongside the CH Profile and PS Profile to implement nodes within the JAS architecture. The SMAC Profile and the Communication...
Reliable Delivery
Specification • JRDDP detects lost packets, duplicate packets, out of sequence packets, and provides damaged data recovery. The protocol provides additional error detection beyond the SpaceWire physical layer by utilizing Cyclic Redundancy Checks (CRCs), packet sequence numbers, positive acknowledgement, and timeouts to detect lost or duplicated Data packets.
Remote Memory Access Protocol
Profile • RMAP is used to access memory devices across a SpaceWire data link. RMAP can be used to support many functions within a JAS-based system, such as: Configure SpaceWire routers Load and control FPGA applications Configure and control sensors Gather state of health information Initializing and retrieving the contents of memory...
Remote Memory Access Protocol
Specification • JAS should use the RMAP standard to remotely access memory devices across the SpaceWire network.
Retransmission
Specification • If an ACK packet is not received by the transmit TEP within a defined channel-specific timeout interval the DATA packet shall be retransmitted.
Routing
Profile • SpaceWire uses wormhole routing to route packets through the network. Each packet contains a header which holds the destination node address either as the route through the network or as the identity of the destination node. As soon as the header for a packet is received the switch determines the...
RP_Applications
Profile • Common instantiations of the RP profile include, but are not limited to: Sensor interface Mission data processing High-Speed Data switch Volatile Memory Storage Softcore processing
Satellite System Description
Other • The beginnings of JAS grew out of the satellite area because there was a need to more effectively approach building satellite payloads to reduce NRE and REC, reduce size, weight and power (SWaP), and respond quickly to national needs for mission applications. JAS Toolbox 1.0 is focused on satellite because...
Screened Venting
Specification • Where venting requires a screen to maintain cleanliness requirements, based on a 5µ Pall Rigidmesh screen, there shall be 1.5 in^2 or greater screen area per ft^3 of volume where the volume is the sum of multiple daisy-chained volumes. The daisy chained volumes shall be vented.
Secondary POL Conversion
Specification • JAS nodes should include POL conversion as needed. POL conversion has become very popular as the voltage requirements of electronic components have continued to drop. It is quite common for many digital electronic devices to use voltages of 1.8 VDC and below. Routing high current, low voltages around a printed...
Sensor Interface and Mission Data Processing
Profile • The primary role of the RP node in this application is to process mission-specific sensor data. Additionally, the node can also be designed to interface to a variety other sensor types by incorporating instantiations of the Expansion Profile. Sensor Interface and Mission Data Processing Instantiation The RP node can also...
Sequence Number Use
Specification • At the receiver TEP the sequence numbers shall be used to detect lost data packets, duplicate packets and to correctly order packets.
Serial RapidIO
Specification •
Serial RapidIO
Specification • Serial RapidIO (or just RapidIO) is a high-performance packet-switched, interconnect technology utilizing either 8b/10b or 64b/67b encoding on data links, or lanes, with speeds up to 6.25 Gbps. Multiple lanes may be used in increase data throughput.
Shielding
Specification • The JAS mechanical structure shall provide EMI shielding which meets 60db shielding effectiveness from 0.1 to 1 GHz for the FPA Sensor box with covers in place.
Softcore Processor Instantiation
Profile • One powerful application that is frequently utilized on FPGA-based platforms is softcore processing. Softcore processors can be instantiated within the FPGA by configuring the FPGA’s logic elements to implement the microprocessor functionality. The microprocessor can easily be integrated with other logic within the FPGA to form a system-on-chip (SoC) architecture....
SOIS Applied to JAS
Profile • A simplified version of the SOIS architecture as applied to JAS is shown in the figure below. The subnetwork services are used by applications to encapsulate and describe the data that needs to be communicated regardless of the underlying physical layer. The subnetwork services are JAS-specific implementations of the respective...
Space VPX
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...
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...
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