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AR# 21559

Spartan-3- What is the correct value for the FACTORY_JF attribute?

Description

What is the correct value for the factory FACTORY_JF attribute in Spartan-3? The Spartan-3 Errata state that the optimal FACTORY_JF setting is x8080, but the instantiation template created by the 8.1i Architecture Wizard gives xC080 for the Low frequency mode and High frequency mode.

Solution

The optimal FACTORY_JF setting for both the Low and High frequency modes is x8080. The Architecture Wizard previously used the incorrect values for the Low and High frequency modes. This issue was fixed starting in ISE 8.2i.

If you use a version of the software that is ISE 8.1i or older, you can manually set the FACTORY_JF attribute through either the User Constraints File (UCF) or HDL Code.

UCF

An easy option to resolve this issue for designs in progress is to apply a user constraint. You can edit an existing UCF or create a new file and add the following constraint for every DCM used in the design.

INST <dcm_inst> FACTORY_JF = "8080";

VHDL

To resolve this issue when using VHDL, update the FACTORY_JF values in both the DCM component declaration and in all component instantiations of the DCM. The following code snippet provides an example for XST VHDL. The VHDL source for other logic synthesis packages might vary slightly.

component DCM -- DCM component declaration

generic(

. . .

FACTORY_JF : bit_vector := x"8080";

. . .

);

. . .

DCM_INST : DCM -- DCM instantiation

generic map(

. . .

FACTORY_JF => x"8080",

. . .

)

Verilog

To resolve this issue when using Verilog, update the FACTORY_JF values as shown in the following XST Verilog code snippet:

DCM DCM_INST (

. . .

);

. . .

// synthesis attribute FACTORY_JF of DCM_INST is "8080"

. . .

// synopsys translate_off

. . .

defparam DCM_INST.FACTORY_JF = 16'h8080;

. . .

// synopsys translate_on

NOTE: If you are editing HDL code generated by the Architecture Wizard, note that Architecture Wizard overwrites the source file each time the Clock Wizard is executed.

AR# 21559
Date Created 09/04/2007
Last Updated 12/15/2012
Status Active
Type General Article