Datasheet

 2013 Microchip Technology Inc. DS22331A-page 119
MCP19111
20.0 INTERRUPT-ON-CHANGE
Each PORTGPA and PORTGPB pin is individually
configurable as an interrupt-on-change pin. Control bits
IOCA and IOCB enable or disable the interrupt function
for each pin. Refer to Register 20-1 and Register 20-2.
The interrupt-on-change is disabled on a Power-on
Reset.
The interrupt-on-change on GPA5 is disabled when
configured as MCLR
pin in the Configuration Word.
For enabled interrupt-on-change pins, the values are
compared with the old value latched on the last read of
PORTGPA or PORTGPB. The mismatched outputs of
the last read of all the PORTGPA and PORTGPB pins
are OR’ed together to set the Interrupt-on-Change
Interrupt Flag bit (IOCF) in the INTCON register
(Register 15-1).
20.1 Enabling the Module
To allow individual port pins to generate an interrupt, the
IOCIE bit of the INTCON register must be set. If the
IOCIE bit is disabled, the edge detection on the pin will
still occur, but an interrupt will not be generated.
20.2 Individual Pin Configuration
To enable a pin to detect an interrupt-on-change, the
associated IOCAx or IOCBx bit of the IOCA or IOCB
register is set.
20.3 Clearing Interrupt Flags
The user, in the Interrupt Service Routine, clears the
interrupt by:
a) Any read of PORTGPA or PORTGPB AND
Clear flag bit IOCF. This will end the mismatch
condition;
OR
b) Any write of PORTGPA or PORTGPB AND
Clear flag bit IOCF will end the mismatch
condition;
A mismatch condition will continue to set flag bit IOCF.
Reading PORTGPA or PORTGPB will end the
mismatch condition and allow flag bit IOCF to be
cleared. The latch holding the last read value is not
affected by a MCLR
Reset. After this Reset, the IOCF
flag will continue to be set if a mismatch is present.
20.4 Operation in Sleep
The interrupt-on-change interrupt sequence will wake
the device from Sleep mode, if the IOCE bit is set.
Note: If a change on the I/O pin should occur
when any PORTGPA or PORTGPB
operation is being executed, then the
IOCF interrupt flag may not get set.