RapidIO Intel FPGA IP User Guide

ID 683884
Date 9/15/2021
Public
Document Table of Contents

4.4.1. Receiver

On the receive side, the Transport layer module receives packets from the Physical layer. Packets travel through the Rx buffer, and any errored packet is eliminated. The Transport layer module routes the packets to one of the Logical layer modules or to the Avalon® -ST pass-through interface based on the packet's destination ID, format type (ftype), and target transaction ID (targetTID) header fields. The destination ID matches only if the transport type (tt) field matches.

Packets with a destination ID different from the content of the relevant Base Device ID CSR ID field are routed to the Avalon® -ST pass-through interface, unless you disable destination ID checking and the packet is a request packet with a tt field that matches the device ID width setting of the IP core. If you disable destination ID checking, the packet is a request packet with a supported ftype, and the tt field matches the device ID width setting of the current RapidIO IP core, the packet is routed to the appropriate Logical layer.

  • Packets with unsupported ftype are routed to the Avalon® -ST pass-through interface. Request packets with a supported ftype and a tt value that matches the RapidIO IP core’s device ID width, but an unsupported ttype are routed to the Logical layer supporting the ftype. The Logical layer module then performs the following tasks:
    • Sends an ERROR response for request packets that require a response.
    • Records an unsupported_transaction error in the Error Management extension registers.
  • Packets that would be routed to the Avalon® -ST pass-through interface, in the case that the RapidIO IP core does not implement an Avalon® -ST pass-through interface, are dropped. In this case, the Transport layer module asserts the rx_packet_dropped signal.
  • ftype=13 response packets are routed based on the value of their target transaction ID (targetTID) field. Each Logical layer module is assigned a range of transaction IDs. If the transaction ID of a received response packet is not within one of the ranges assigned to one of the enabled Logical layer modules, the packet is routed to the pass-through interface.

Packets marked as errored by the Physical layer (for example, packets with a CRC error or packets that were stomped) are filtered out and dropped from the stream of packets sent to the Logical layer modules or pass-through interface. In these cases, the rx_packet_dropped output signal is not asserted.