Altera RapidIO II MegaCore Function - Manual (Page 33)

Chapter 3: Parameter Settings 3–3
Transport Layer Settings
August 2014 Altera Corporation RapidIO II MegaCore Function
User Guide
Transport Layer Settings
The Transport layer settings specify properties of the Transport layer in your
RapidIO II IP core variation. These parameters determine whether the RapidIO II IP
core uses 8-bit or 16-bit device IDs, whether the Transport layer has an Avalon-ST
pass-through interface, and how the RapidIO II IP core handles a request packet with
a supported ftype but a destination ID not assigned to this endpoint.
Enable 16-Bit Device ID Width
The Enable 16-bit device ID width setting specifies a device ID width of 8-bit or
16-bit
. RapidIO packets contain destination ID and source ID fields, which have the
specified width. If this IP core uses 16-bit device IDs, it supports large common
transport systems.
The two parameter values do not cause symmetrical behavior. If you turn on this
option, the IP core can still support user logic that processes packets with 8-bit device
IDs. You can parameterize the IP core to route such packets to the Avalon-ST pass-
through interface, where user logic might handle it. However, if you turn off this
option, the RapidIO II IP core drops all incoming packets with a 16-bit device ID.
Refer to
“Transport Layer” on page 4–70 .
Enable Avalon-ST Pass-Through Interface
Turn on Enable Avalon-ST pass-through interface to include the Avalon-ST
pass-through interface in your RapidIO II variation.
The Transport layer routes all unrecognized packets to the Avalon-ST pass-through
interface. Unrecognized packets are those that contain Format Types (ftypes) for
Logical layers not enabled in this IP core, or destination IDs not assigned to this
endpoint. However, if you disable destination ID checking, the packet is a request
packet with a supported ftype, and the Transport Type (tt) field of the packet
matches the device ID width setting of this IP core, the packet is routed to the
appropriate Logical layer.
1 The destination ID can match this endpoint only if the tt field in the packet matches
the device ID width setting of the endpoint.
Request packets with a supported ftype and correct tt field, but an unsupported
ttype
, are routed to the Logical layer supporting the ftype, which allows the
following tasks:
■ An ERROR response can be sent to requests that require a response.
■ An unsupported_transaction error can be recorded in the Error Management
extension registers.
Response packets are routed to a Logical layer module or the Avalon-ST pass-through
port based on the value of the target transaction ID field. For more information, refer
to
Table 4–23 on page 4–48 , which defines the transaction ID ranges.