Texas Instruments TMS320TCI648x - Manual (Page 18)

www.ti.com
1.1.2 RapidIO Interconnect Architecture
Host Subsystem
I/O Control Subsystem
DSP Farm
TDM,GMII, Utopia
Communications Subsystem PCI Subsystem
InfiniBand HCA ™
To System Area
Network
Memory
Memory Memory
Memory
RapidIO RapidIO RapidIO
RapidIO
RapidIO
Backplane
PCI
RapidIO
RapidIO
RapidIO
RapidIO
Switch
Control
Processor
IO
Processor
RapidIO to
InfiniBand
RapidIO
Switch
RapidIO
Switch
Legacy
Comm
Processor
RapidIO
Switch
RapidIO to
PCI Bridge
ASIC/FPGA
Memory Memory
Host
Processor
Host
Processor
DSP DSP DSP DSP
Comm
Processor
1.1.3 Physical Layer 1x/4x LP-Serial Specification
Overview
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.
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 RapidIO Physical Layer 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 8-bit/10-bit
encoding scheme ensures ample data transitions for the clock recovery circuits. Due to the 8-bit/10-bit
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.
Figure 3 shows how to interface two 1x devices and two 4x devices. Each positive transmit data line (TDx)
on one device is connected to a positive receive data line (RDx) on the other device. Likewise, each
negative transmit data line (TDx) is connected to a negative receive data line (RDx).
18 Serial RapidIO (SRIO) SPRUE13A – September 2006
Submit Documentation Feedback