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AR# 17607

6.1i BitGen - The default FreezeDCI option for Virtex-II/-II Pro might result in a larger bit file than the ones generated by 5.2i causing custom configuration to fail (DONE stays Low) in designs containing DCI

Description

General Description:  

In 6.1i, FreezeDCI is set to "Yes" rather than "No" if BitGen detects DCI in design. This might create problems in custom slave configuration (Slave Serial, or Slave SelectMap), where only a set number of startup clocks is sent to the FPGA, resulting in DONE pin staying Low.  

 

This is not a problem with iMPACT, as iMPACT provides additional clocks to account for this change.

Solution

To work around this issue, use one of the following solutions: 

- Send in more startup clocks. 

- Explicitly set the FreezeDCI option in BitGen to "No" for Virtex-II devices (e.g., -g FreezeDCI:no). 

- Set DCIUpdateMode rather than FreezeDCI option for Virtex-II Pro/Spartan-3 devices. 

 

To see the supported BitGen options, use "bitgen -help". 

 

Example:  

bitgen -help virtex2" or "bitgen -help virtex2p

AR# 17607
Date Created 09/03/2007
Last Updated 05/15/2014
Status Archive
Type General Article