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AR# 8197

FPGA Configuration - Configuration data is incorrect


If the configuration data is incorrect, the FPGA will never properly configure. There are a number of things the user can do to determine if this is the case.


4000/Spartan/5200 Families 


It is highly unlikely that the loading of incorrect configuration data would not result in a DataFrame ERROR (INIT goes low); however, if the Preamble sequence <0010> is never observed by the FPGA, then the configuration process would never have started. Thus, no error would be detected.  


Check to see if the data is backwards. If the configuration data is being accessed in byte words and shifted serially into the FPGA, then shifting in the wrong direction would result in observing <0000 0100> instead of <0010 0000> on DOUT.  


If the data is simply incorrect, then this is most likely a result of a problem in the application board or timing specification requirements not being properly met. 


Virtex Families 


The Virtex family does not produce any output on DOUT during configuration as the 4000 series did; however, there is a synchronization word that must be loaded before configuration begins.  


First, verify that the 32-bit synchronization word (0xAA995566) is being properly passed into the device. Once the correct data into the device has been verified, it is now possible to verify that the Virtex device received the information correctly. (Xilinx Solution 7891) documents this process in detail.

AR# 8197
Date Created 08/21/2007
Last Updated 05/14/2014
Status Archive
Type General Article