If you are using Active Serial or Active Parallel configuration mode in Cyclone® III, Cyclone IV E, or Cyclone IV GX devices and have assigned a non-default current strength setting to the configuration pins, the Intel® Quartus® Prime Software legality check will report the following error:
Error (169187): Following feature(s) of I/O pin <pin_name> has invalid setting(s) in the configuration scheme ACTIVE_SERIAL when the pin is placed at pin location <pin_location>Info (169189): I/O feature 'Current Strength' has an invalid setting. The setting should be Default.
The requirement for all Cyclone III, Cyclone IV E, and Cyclone IV GX devices is to set the following default settings on the Active Serial or Active Parallel configuration pins:
a. Weak pull up = on
b. Bushold = off
c. PCI_IO = off
d. Slew rate = 2
e. Open drain = off
f. Vod = -1
g. Pre-emphasis = -1
h. Current strength = default
i. I/O standard = 3.3/3.0/2.5/1.8 (LVTTL/LVCMOS)