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General Description: I use iMPACT to configure a JTAG chain containing multiple Virtex-II devices, and the DONE signal goes High; however, the first device in the chain does not become operational. (The DONE pins on both devices are tied together.)
Virtex-II devices with tied DONE signals will not configure correctly through JTAG. (This is because iMPACT fails to clock the first device through the startup sequence.)
This problem does not apply to the following scenarios:
- JTAG chains containing only one Virtex-II device - JTAG chains containing multiple Virtex-II devices that do not have tied DONE pins
There are three ways to work around this problem:
1. In BitGen, set the DONE cycle for GTS and GWE.
2. Program the entire chain of Virtex-II devices via JTAG, then reprogram the first Virtex-II device by itself.
3. Do not tie the DONE pins together on the Virtex-II devices. (This option may not be viable if other configuration methods are to be used on the board.)
This problem will be fixed in the 5.1i software, which is scheduled to be released in September, 2002.