RapidIO: The Next Generation Communication Fabric For Embedded Application

Chapter 7. The Serial Physical Layer

The RapidIO serial physical layer, typically referred to as Serial RapidIO, addresses the electrical connection of devices on a board or across a backplane. The serial physical layer defines a full duplex serial link between devices using unidirectional differential signals in each direction. The serial physical layer protocol provides support for packet delivery between RapidIO devices. This support includes packet and control symbol transmission, flow control, error management, and other device-to-device functions.

The RapidIO serial physical layer has the following properties:

• Embeds the transmission clock with data using an 8B/10B encoding scheme.

• Supports one serial differential pair, referred to as one lane, or four ganged serial differential pairs, referred to as four lanes, in each direction.

• Uses special 8B/10B codes, called K-codes, to manage the link, including flow control, packet demarcation, and error reporting.

• Allows transferring packets between RapidIO 1x/4x LP-Serial (Serial RapidIO) Ports and RapidIO Physical Layer 8/16 LP-LVDS (Parallel RapidIO) ports without requiring packet manipulation.

• Employs similar retry and error recovery protocols to those of the Parallel RapidIO physical layer.

• Supports transmission rates of 1.25, 2.5, and 3.125 Gbaud (data rates of 1.0, 2.0, and 2.5 Gbps) per lane.

This chapter first defines the individual elements that make up the serial link protocol such as packets, control symbols, and the serial ...