We’re now having some difficulty with JTAG programming, with some strange results! Programming using a bit file through front panel is fine, but when we try to program via JTAG, the system fails to start. iMPACT verifies that the programming was ok, but nothing happens. The really strange part though, is that if we program via front panel first, and then try jtag, it works a treat, even if the jtag config file is different. Unfortunately, after a power-down the only way to configure is through fp again.
We’ve looked into the spartan startup sequence, and think we might have to do something with the INIT or PROG pins, though this doesn’t explain why JTAG works after a USB operation! Any help would, as always, be appreciated.