When executing the KEY_VERIFY instruction, why are register bits related to the volatile key sometimes set after power-up, even though no key is programmed in Stratix V, Arria V or Cyclone V devices?

Description

You may observe register bits related to the volatile key sometimes being set after power-up when executing the KEY_VERIFY JTAG instruction, even though no key is programmed in Stratix® V, Arria® V or Cyclone® V devices. This is because there is no power-up reset for the registers that are powered by VCCBAT, so these bits are undefined at power-up.

This will not cause an issue with programming the key.