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AR# 36123

12.1 iMPACT - Why do I see all 0s or all 1s when I attempt to read back the DNA from Spartan-6 FPGA using iMPACT, and how do I resolve this problem?

Description

Why do I see all 0s when I attempt to read back the DNA from Spartan-6 FPGA using iMPACT, and how do I resolve this problem?

Solution


NOTE: Ensure that you are reading back from an unconfigured device. If the device is configured, the DNA reads back as all '1'. To ensure thedevice is unconfigured, erase configuration flash, or change mode pins and Power cycle or pulse PROG.
The BSDL ".bsd" files of Spartan-6 FPGA define incorrect DNA readback instructions.
Open the ".bsd" file corresponding to your targerting part and change the following:

"ISC_DNA (010111)";

to:

"ISC_DNA (110000)";

The issue is resolved when the above changes are made.

Notes:
  1. This solution applies to Spartan-6 FPGA Production silicon only. This is because the DNA features can be supported by Production silicon only (i.e., ES silicon cannot support the DNA feature). Refer to the erratas for each part to determine whether or not the part you are using can support DNA.
  2. The BSDL files are located in the ISE Design Suite install flolders. You only need to modify the general ".bsd" file of the part you are targeting (i.e., you do not need to modify the package-specific ".bsd" files). For example, if the target device isxc6slx150t-fgg900, you only modifyxc6slx150t.bsd and do not need to modifyxc6slx150t_fgg900.bsd.
  3. This issue is scheduled to be fixed in version 12.2 of the software.
AR# 36123
Date Created 06/10/2010
Last Updated 12/15/2012
Status Active
Type General Article
Devices
  • Spartan-6 LX
  • Spartan-6 LXT