Intel® Cyclone® 10 GX Transceiver PHY User Guide

ID 683054
Date 4/14/2023
Public
Document Table of Contents

5.2.2.10.5. Idle OS Deletion

Deletion of Idles occurs in groups of four OS (when there are two consecutive OS) until the rx_enh_fifo_pfull flag deasserts. Every word—consisting of a lower word (LW) and an upper word (UW)—is checked for whether it can be deleted by looking at both the current and previous words.

For example, the current LW can be deleted if it is Idle and the previous UW is not a Terminate.

Table 182.   Conditions Under Which a Word Can be DeletedIn this table X=don’t care, T=Terminate, I=Idle, and OS=order set.
Deletable Case Word Previous Current Output
Lower Word 1 UW !T X !T X
LW X I X X
2 UW OS X OS X
LW X OS X X
Upper Word 1 UW X I X X
LW X !T X !T
2 UW X OS X X
LW X OS X OS

If only one word is deleted, data shifting is necessary because the datapath is two words wide. After two words have been deleted, the FIFO stops writing for one cycle and a synchronous flag (rx_control[8]) appears on the next block of 8-byte data. There is also an asynchronous status signal rx_enh_fifo_del, which does not go through the FIFO.

Figure 191.  IDLE Word DeletionThis figure shows the deletion of IDLE words from the receiver data stream.
Figure 192.  OS Word DeletionThis figure shows the deletion of Ordered set words in the receiver data stream.