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Host Subsystem
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TDM,GMII, Utopia
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™
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ASIC/FPGA
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Comm
Processor
Overview
1.1.2
RapidIO Interconnect Architecture
The interconnect architecture is defined as a packet switched protocol independent of a physical layer
implementation.
Figure 2
illustrates the interconnection system.
Figure 2. RapidIO Interconnect Architecture
(1)
InfiniBand™ is a trademark of the InfiniBand Trade Association.
1.1.3
1x/4x LP-Serial
Currently, there are two physical layer specifications recognized by the RapidIO Trade Association: 8/16
LP-LVDS and 1X/4X LP-Serial. The 8/16 LP-LVDS specification is a point-to-point synchronous clock
sourcing DDR interface. The 1X/4X LP-Serial specification is a point-to-point, AC coupled, clock recovery
interface. The two physical layer specifications are not compatible.
SRIO complies with the 1X/4X LP-Serial specification. The serializer/deserializer (SERDES) technology in
SRIO also aligns with that specification.
The 1X/4X LP-Serial specification currently covers three frequency points: 1.25, 2.5, and 3.125 Gbps. This
defines the total bandwidth of each differential pair of I/O signals. An 8b/10b encoding scheme ensures
ample data transitions for the clock recovery circuits. Due to the 8b/10b encoding overhead, the effective
data bandwidth per differential pair is 1.0, 2.0, and 2.5 Gbps respectively. Serial RapidIO only specifies
these rates for both the 1X and 4X ports. A 1X port is defined as 1 TX and 1 RX differential pair. A 4X port
is a combination of four of these pairs. This document describes a 4X RapidIO port that can also be
configured as four 1X ports, thus providing a scalable interface capable of supporting a data bandwidth of
1 to 10 Gbps.
16
Serial RapidIO (SRIO)
SPRU976 – March 2006
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