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Texas Instruments TMS320C645X User Manual

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Initiator

Request

Packet Issued

Operation

Completed for

Master

Acknowledge

Symbol

Acknowledge

Symbol

Response

Packet

Forwarded

Request Packet

Forwarded

Acknowledge

Symbol

Acknowledge

Symbol

Response Packet

Issued

Fabric

Target

Target

Completes

Operation

Operation
Issued By

Master

SRIO Functional Description

SRIO endpoints are typically not connected directly to each other but instead have intervening connection
fabric devices. Control symbols are used to manage the flow of transactions in the SRIO physical
interconnect. Control symbols are used for packet acknowledgment, flow control information, and
maintenance functions.

Figure 5

shows how a packet progresses through the system.

Figure 5. Operation Sequence

2.1.2.2

Example Packet – Streaming Write

An example packet is shown as two data streams in

Figure 6

. The first is for payload sizes of 80 bytes or

less, while the second applies to payload sizes of 80 to 256 bytes. SRIO packets must have a length that
is an even integer of 32 bits. If the combination of physical, logical and transport layers has a length that is
an integer of 16 bits, a 16-bit pad of value 0x0000 is added to the end of the packet, after the CRC (not
shown). Bit fields that are defined as reserved are assigned to logic 0s when generated and ignored when
received. All request and response packet formats are described in the I/O and Message Passing Logical
Specifications.

SPRU976 – March 2006

Serial RapidIO (SRIO)

21

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