I am trying to perform readback of the configuration for a Virtex-4. I followed the steps in the configuration guide, but have had little luck. The ICAP syncs up (output is 0xDF) and never enters ABORT when I give it commands; however, when I disable the ICAP, switch to read mode, and then re-enable the ICAP, the BUSY signal goes high, I do not recieve any configuration data, and the ICAP output remains 0xDF.
Has anyone experienced this problem and know a correction or had success with readback and can inform me of their process?
Thanks.