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AR# 50776

Design Advisory - iMPACT - Spartan-3AN - SVF file generated to Erase will not erase ISF flash set to Power-of-2 mode


SVF files generated by iMPACT to Erase the ISF flash on a Spartan-3AN FPGA will not erase all sectors if Power-of-2 addressing is enabled in the flash. This can lead to programming failures using SVF, ACE and XSVF programming. The issue is that the Sector Erase algorithm assumes the factory-default addressing mode rather than Power-of-2 and so will not address all sectors. A blank check will fail and a readback will show some sectors are not erased. This issue will be masked on new devices as the flash is shipped by Xilinx blank. This issue will only effect ISF flash which has been set to Power-of-2 mode manually to program the OTP bit on the flash. The issue only affects SVF/XSVF/ACE mode. There is a potential for failures at manufacturing or during field upgrades using XAPP058 (XSVF player), XAPP424 (ACE player), third-party SVF/STAPL-based solutions, or custom JTAG where new images have been deployed to update previously programmed Spartan-3AN devices.


To work around this issue, the SVF must be generated with iMPACT connected to a Spartan-3AN FPGA which has the ISF flash set to Power-of-2 mode. The board you connect to must have Power-of-2 mode set. Use the "Read Device Status" option in the Debug menu to Verify that the flash is set to Power-of-2 mode.

Procedure to generate a working SVF for Power-of-2 mode flash in iMPACT 14.2 and earlier:

(1) Open iMPACT and connect to Spartan-3AN board with Power-of-2 mode ISF flash
(2) Assign a .bit or MCS file to the Spartan-3AN
(3) Select the "Program Flash and load FPGA" option
(4) After programming completes, switch to SVF mode
(5) Carry out operations required for your SVF file

Using an SVF generated with this procedure will always program Power-of-2 flash correctly. This issue will be resolved in iMPACT 14.3.

Procedure to generate a working SVF for Power-of-2 mode flash in iMPACT 14.3 and later:

Work around 1

Set the environment variable XIL_IMPACT_POWEROFTWO = 1. This will result in all SVF files targeting Spartan-3AN being generated in Power-of-2 mode.

Work Around 2

Generate the SVF file in batch mode using the "-po2" switch added in iMPACT 14.3 Example batch command to generate SVF file targetting a Spartan-3AN starter kit -

setCable -port svf -file "<path>/batch.svf"
addDevice -p 1 -fpga "xc3s700an" -file "<path>/default.mcs"
setAttribute -position 1 -attr packageName -value ""
addDevice -p 2 -file "<path/>xcf04s.bsd"
Erase -po2 -p 1

AR# 50776
Date 07/27/2012
Status Active
Type General Article
  • Spartan-3AN
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