Each FPGA should be used as if it had one ICAPE3 resource, although
there are actually two ICAPE3 resources per die for improved SEU protection. The
tools automatically use the top ICAPE3 by default and the most common use case.
Control register 0 Bit 30 (ICAP_SELECT) enables the top ICAPE3 site when set to
0 (default), and enables the bottom ICAPE3 site
when set to 1. User switching can be done by
toggling the control register CTL0[bit 30] using the currently active ICAPE3. The
device can automatically switch between the two ICAPE3 sites if enabled using the
ICAP_AUTO_SWITCH attribute, using a sync word on 8 LSBs.
Recommended: Only one ICAPE3 resource
should be instantiated for a Spartan UltraScale+ FPGA, and it should be automatically placed by the tools when using SEM IP.