The architecture of the SpaceWire router ASIC is illustrated in Figure 57.
Figure 57 ESA SpW-10X SpaceWire Router ASIC Architecture
There are eight SpaceWire ports, two external ports and an internal configuration port in the SpaceWire router. A low latency, worm-hole routing, non-blocking, crossbar switch enables packets arriving at any SpaceWire port, external port or generated in the configuration port to be directed out of any other SpaceWire or external port or to be routed to the configuration port.
The SpaceWire ports are compliant with the SpaceWire standard providing high-speed, bi-directional communications. The FIFO ports each comprise an input FIFO and an output FIFO and can receive and send data characters and end of packet markers. A time-code port is also provided along with a time-counter to facilitate the propagation of time-codes, see the section “Time-Codes“. When a valid time-code arrives at a router port it is sent out of all the other SpaceWire ports and a TICK_OUT signal is generated at the time-code port. The router can operate as a time-code master using the TICK_IN provided in the time-code port.
The configuration port is accessible via any of the SpaceWire or external ports. It contains registers which control the operation of the SpaceWire ports, external ports and the crossbar switch. The configuration port holds status registers for the various ports and the switch. These registers can be read using a configuration read command to determine the status of the router and to access error information. Status and error information can also be selected for output on several status pins. The routing table is accessed via the configuration port. The logical address port mappings and priority bits can be set in the routing table. The routing table is used to control group adaptive routing and priority arbitration in the crossbar switch.
The SpW-10X was designed by the University of Dundee, transferred to radiation hard technology by Austrian Aerospace, and is manufactured by Atmel and sold as the AT7910E device. It is packaged in a space qualified 256 pin QFP package, see Figure 58.
Figure 58 Photograph of SpW-10X Router ASIC