Pin Change Enable
Mask
Each
PCINT[38:32]-bit selects whether pin change interrupt is enabled on the
corresponding I/O pin. If PCINT[38:32] is set and the PCIE4 bit in PCICR is set, pin
change interrupt is enabled on the corresponding I/O pin. If PCINT[38:32] is
cleared, pin change interrupt on the corresponding I/O pin is
disabled.