AR# 47943

LogiCORE IP Ten Gigabit Ethernet PCS/PMA (10GBASE-R/10GBASE-KR) v2.3 - In Asynchronous Systems the RX Elastic Buffer Can Incorrectly Empty

Description

In the Ten Gigabit Ethernet PCS/PMA (10GBASE-R/10GBASE-KR v2.3 core extra delay was added to the synchronization across the clock domain boundaries.

As a result of this, the occupancy level calculation lagged by a couple of cycles.

This meant that the FIFO status was reporting that the FIFO had a higher occupancy than it actually had.

As a result, the idle insertion can sometimes not be flagged and the FIFO will run empty.

Solution

The fix in the below v2.3 rev1 patch is to have the occupancy level calculated on a pipelined version of the write address to account for the read address sync stages and report the correct occupancy.

Installation/Use: This patch is for use with ISE 14.1 and Vivado 2012.1 design tools.

Install the patch below by extracting the contents of the ".zip" archive to the root directory of the XILINX (Xilinx ISE installation).

Select the option that allows the extractor to overwrite all of the existing files and maintain the directory structure predefined in the archive.

For further information on finding the Xilinx install and using environment variable, see (Xilinx Answer 11630).

Note: You might be required to have a system administrator to install the patch if you do not have write permissions to the Xilinx Install directory.

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Associated Attachments

Name	File Size	File Type
ar47943_ten_gig_eth_pcs_pma_v2_3_rev1.zip	37 KB	ZIP

AR# 47943
Date	10/17/2014
Status	Active
Type	Design Advisory
Devices	Kintex-7 Virtex-7
IP	10 Gigabit Ethernet PCS-PMA with FEC/Auto-Negotiation for backplanes (10GBASE-KR)

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