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AR# 59978

14.7 EDK - XPS_LL_TEMAC v2.03.a - Wrong transceiver RX termination voltage used for Virtex-5

Description

When the XPS LocalLink 3-mode Ethernet MAC IP is built for Virtex-5, the GT is configured with the wrong RX termination voltage.

The core uses AC_CAP_DIS_0 = TRUE in conjunction with RCV_TERM_VTTRX = TRUE", which is not a valid setting. 

With built-in AC coupling disabled, the RX termination voltage should be set to 2/3 MGTAVTTRX per Table 7-3 of UG198. 

However, with RCV_TERM_VTTRX = TRUE" and "RVC_TERM_GND = "FALSE", the termination voltage is incorrectly set to MGTAVTTRX. 

This setting can lead to communication failures.  

Solution

The Coregen SGMII core and V5 GTX Wizard correctly sets the RX termination voltage to 2/3 MGTAVTTRX by default:

        .AC_CAP_DIS_0               ("TRUE"),

        .OOBDETECT_THRESHOLD_0      (3'b111),

        .PMA_CDR_SCAN_0             (27'h6404035),

        .PMA_RX_CFG_0               (25'h0f44088),

        .RCV_TERM_GND_0             ("FALSE"),

        .RCV_TERM_VTTRX_0           ("FALSE"),

        .TERMINATION_IMP_0          (50),


Change the RCV_TERM_VTTRX setting to "FALSE" in order to use the recommended receiver termination voltage.

AR# 59978
Date Created 03/27/2014
Last Updated 10/23/2014
Status Active
Type General Article
Devices
  • Virtex-5
IP
  • XPS LL TEMAC