Arria® V Device Handbook: Volume 2: Transceivers

ID 683573
Date 5/29/2020
Public
Document Table of Contents

5.1.2.2. Rate Match FIFO Behaviors in Custom Double-Width Mode

The different operations available in custom double-width mode for the rate match FIFO are symbol insertion, symbol deletion, full condition, and empty condition.
Table 72.  Rate Match FIFO Behaviors in Custom Double-Width Mode (20-bit PMA–PCS Interface Width)
Operation Behavior
Symbol Insertion Inserts as many pairs (10-bit skip patterns at the LSByte and MSByte of the 20-bit word at the same clock cycle) of skip patterns as needed.
Symbol Deletion Deletes as many pairs (10-bit skip patterns at the LSByte and MSByte of the 20-bit word at the same clock cycle) of skip patterns as needed.
Full Condition Deletes the pair (20-bit word) of data bytes that causes the FIFO to go full.
Empty Condition Inserts a pair of /K30.7/ ({9'h1FE, 9'h1FE}) after the data byte that causes the FIFO to go empty.

In this example, /K28.5/ is the control pattern and neutral disparity /K28.0/ is the skip pattern. The first skip cluster has a /K28.5/ control pattern in the LSByte and /K28.0/ skip pattern in the MSByte of a clock cycle followed by one /K28.0/ skip pattern in the LSByte of the next clock cycle. The rate match FIFO cannot delete the two skip patterns in this skip cluster because they do not appear in the same clock cycle. The second skip cluster has a /K28.5/ control pattern in the MSByte of a clock cycle followed by two pairs of /K28.0/ skip patterns in the next two cycles. The rate match FIFO deletes both pairs of /K28.0/ skip patterns (for a total of four skip patterns deleted) from the second skip cluster to meet the three skip pattern deletion requirement.

Figure 142. Rate Match Deletion in Custom Double-Width ModeThe following figure shows an example of rate match FIFO deletion in the case where three skip patterns are required to be deleted.


In this example, /K28.5/ is the control pattern and neutral disparity /K28.0/ is the skip pattern. The first skip cluster has a /K28.5/ control pattern in the LSByte and /K28.0/ skip pattern in the MSByte of a clock cycle followed by one /K28.0/ skip pattern in the LSByte of the next clock cycle. The rate match FIFO inserts pairs of skip patterns in this skip cluster to meet the three skip pattern insertion requirement.

Figure 143. Rate Match Insertion in Custom Double-Width ModeThe following figure shows an example of rate match FIFO insertion in the case where three skip patterns are required to be inserted.


Figure 144. Rate Match FIFO Full Condition in Custom Double-Width Mode The following figure shows the rate match FIFO full condition in custom double-width mode. The rate match FIFO becomes full after receiving the 20-bit word D5D6.


Figure 145. Rate Match FIFO Empty Condition in Custom Double-Width ModeThe following figure shows the rate match FIFO empty condition in custom double-width mode. The rate match FIFO becomes empty after reading out the 20-bit word D5D6.