My Cyclone IV E (EP4CE6 E144 package) is in a weird state. I have pullup resistors on CONF_DONE, nSTATUS, and nCONFIG. nCE is pulled low. All four of these pins have low voltage readings. (< 20 mV) The strange thing is that nCONFIG is low even though it's pulled high. I suppose that means it's stuck in POR (Power on reset).I've checked my power pins and they all seem fine. The only problem with my circuit is that the exposed pad at the bottom is not connected to ground. I just found out that this is actually a necessary electrical ground connection. Before I go through the trouble of unsoldering my FPGA and inserting a wire below it and resoldering it, I'd like to know if what I'm seeing is indeed a symptom of not having connected the exposed ground pad. Has anyone encountered this scenario before?
The device can't be expected to work with unconnected exposed pad, the problem has been quite often reported for Cyclone III and Cyclone IV.Some people managed to drill a hole from the bottom side and connect the exposed pad, don't know if it might be possible with your board.