GR740-UM-DS, Nov 2017, Version 1.7
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GR740
13
SpaceWire router
13.1
Overview
The SpaceWire router implements a SpaceWire routing switch as defined in [SPW]. It provides an
Remote Memory Access Protocol (RMAP) target according to [RMAP] for configuration at port 0
used for accessing internal configuration and status registers. In addition to this there are two different
port types: SpaceWire ports and AMBA ports. The router implements a total of eight SpaceWire ports
and four AMBA ports.
Among the features supported by the router are: group adaptive routing, packet distribution, system
time-distribution, distributed interrupts, port timers to recover from deadlock situations, SpaceWire-D
[SPWD] packet truncation based time-slot violations, and SpaceWire Plug-and-Play [SPWPNP].
Note: LVDS drivers that are not used in the application can be turned off to save power. This is con-
trolled via the register bank interface. Note that there is no automatic turning off of the LVDS drivers
of disabled or inactive SpaceWire links in this device, so this must be managed by the application
software. See section 3.5 for further information.
13.2
Operation
The router ports are interconnected using a non-blocking switch matrix which can connect any input
port to any output port. Access to each output port is arbitrated using a round-robin arbitration
scheme. A single routing-table is used for the whole router. Access to the table is also arbitrated using
a round-robin scheme.
The ports consist of configuration port 0 and two different types of external ports: SpaceWire links
and AMBA interfaces. All ports have the same interface to the switch matrix and behave in the same
manner. The difference in behavior is on the external side of the port. The SpaceWire ports provide
standard SpaceWire link interfaces using on-chip LVDS. The AMBA ports transfer characters from
and to an AHB bus using DMA. The different port types are described in further detail in sections
13.3, 13.4 and 13.5.
Figure 11.
Block diagram