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AR# 25111

Virtex-5 GTP RocketIO - 9.1 Certain attributes must be set in the UCF file


In ISE 9.1 Service Pack 3 and earlier, there are a few attributes in GTP that cannot be synthesized but must be changed from the default.

These defaults can be changed by adding constraints to the UCF file.

These attributes were added to the GTP_DUAL primitive and their defaults updated in ISE 9.2i.

In ISE 9.2i and later, after which they are no longer required in the UCF.



This must be set only when the TX Buffer is bypassed. 

The example UCF file generated by the GTP Wizard v1.3, 1.4, and 1.5 will contain this constraint only when the TX Buffer is bypassed. If the TX Buffer is used, no action is required.

When the TX Buffer is bypassed, PMA_COM_CFG should be set to: 90'h00000000000000000000450

Example UCF constraint:

INST .../gtp_dual_i PMA_COM_CFG = "90'h00000000000000000000450";


This attribute affects transmitter jitter performance when PLL_DIVSEL_FB is set to 1. 

When PLL_DIVSEL_FB is set to 2, 3, 4, or 5, no additional action is required by the user.

If PLL_DIVSEL_FB = 1, PCS_COM_CFG = 0x1680A07

Example UCF constraint:

INST .../gtp_dual_i PCS_COM_CFG = "28'h1680A07";

If PLL_DIVSEL_FB = 2, 3, 4, or 5, no additional action is required.

Version 1.5 of the GTP Wizard will set this in the example UCF when PLL_DIVSEL_FB = 1.

AR# 25111
Date 06/22/2017
Status Active
Type General Article
  • Virtex-5 LXT
  • Virtex-5 SXT
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