RapidIO Intel FPGA IP User Guide

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

4.3.6. Physical Layer Receive Buffer

The Physical layer passes data to the Transport layer through a Physical layer receive buffer.. The data passes between the buffer and the Transport layer on a bus that is 32 bits wide in 1x variations and 64 bits wide in 2x and 4x variations.

The Physical layer receiver block accepts packet data from the low-level interface receiver module and stores the data in its receive buffer. The receive buffer provides clock decoupling between the Physical layer rxclk clock domain and the Transport layer sysclk clock domain.

You can specify a value of 4, 8, 16, or 32 KBytes to configure the receive buffer size in devices other than Intel® Arria® 10 and Intel® Cyclone® 10 GX. RapidIO Intel® Arria® 10 and Intel® Cyclone® 10 GX variations have a receive buffer size of 32 KBytes. The receiver buffer is partitioned into 64-byte blocks that are allocated from a free queue and returned to the free queue when no longer needed. The IP core provides the current number of 64-byte blocks in the free queue in the arxwlevel output signal.

As many as five 64-byte blocks may be required to store a packet.