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Setting pins connected to other chips to tristate isn't a good idea, because the pins float to an unknown value, vcc or gnd is even worse, because you have to assure, that no pin is driving out, possibly damaging a FPGA pin by a high short circuit current. You should select either tristate with weak pull-up or hold-circuit for unconfigured pins.
As said, there's no simple explanation for the observed behaviour. It may be the case, that a floating tri-state pin enabled the connected device in an unexpected way and caused switching noise affecting other parts of the circuit. Also a high current consumption can overload the power supply in this situation.
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okay, then i will try flashing again without the vcc and tri-state, and set to the option as you suggested, and will update with the results.
thanks for the support
Honored Contributor
