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AR# 23128

8.1i iMPACT : XC9500 devices in a JTAG chain fail to program/verify properly


I find when programming an XC9500 device in a chain of JTAG-enabled devices, a device will fail to pass a verify operation.  

When the failure occurs, it will be repeatable. What is causing this?


There is a bug in the way the JTAG data is sent into the JTAG chain. The data sent in is improperly formatted, and 

there is a dependance on the design pattern, as well as the chain length and the position of the device being programmed in the chain. 

Devices that do not exhibit verification failures are programmed properly and are not affected by this bug. 


This bug does not affect the XC9500XL, XC9500XV, or CoolRunner product families. 


This problem has been fixed in the latest 8.1i Service Pack available at: 

The first service pack containing the fix is 8.1i Service Pack 3.

AR# 23128
Date Created 09/04/2007
Last Updated 05/20/2014
Status Archive
Type General Article