During general-purpose I/O (GPIO) characterization for the
Cyclone® V and Arria® V devices, the default
in the Quartus® II software is 0000; this value does not provide
the correct RT value within the specified range.
This issue is fixed in the 13.1 Quartus II software release.
For all VCCIO in the 13.0 Quartus II software release, modify
RTadjust[3:0] value to 1111 to provide a more accurate
RT value for all VCCIO levels except for VCCIO 2.5V, RT=50ohm. For
VCCIO 2.5V, modify the
RTadjust[3:0] value to 0001
RTMULT value to 010 to reduce the large variation.