PIC18F2682-I/PT MICROCHIP [Microchip Technology], PIC18F2682-I/PT Datasheet - Page 262

• Manufacturer Part Number: PIC18F2682-I/PT
• Description: 28/40/44-Pin Enhanced Flash Microcontrollers with ECAN Technology, 10-Bit A/D and nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F2682/2685/4682/4685
FIGURE 20-3:
20.6
The comparator interrupt flag is set whenever there is
a change in the output value of either comparator.
Software will need to maintain information about the
status of the output bits, as read from CMCON<7:6>, to
determine the actual change that occurred. The CMIF
bit (PIR2<6>) is the Comparator Interrupt Flag. The
CMIF bit must be reset by clearing it. Since it is also
possible to write a ‘1’ to this register, a simulated
interrupt may be initiated.
Both the CMIE bit (PIE2<6>) and the PEIE bit
(INTCON<6>) must be set to enable the interrupt. In
addition, the GIE bit (INTCON<7>) must also be set. If
any of these bits are clear, the interrupt is not enabled,
though the CMIF bit will still be set if an interrupt
condition occurs.
The user, in the Interrupt Service Routine, can clear the
interrupt in the following manner:
a)
b)
A mismatch condition will continue to set flag bit CMIF.
Reading CMCON will end the mismatch condition and
allow flag bit CMIF to be cleared.
DS39761B-page 260
Note:
Port pins
Any read or write of CMCON will end the
mismatch condition.
Clear flag bit CMIF.
Comparator Interrupts
If a change in the CMCON register
(C1OUT or C2OUT) should occur when a
read operation is being executed (start of
the Q2 cycle), then the CMIF (PIR
registers) interrupt flag may not get set.
Read CMCON
COMPARATOR OUTPUT BLOCK DIAGRAM
CxINV
Reset
Preliminary
20.7
When a comparator is active and the device is placed
in Sleep mode, the comparator remains active and the
interrupt is functional if enabled. This interrupt will
wake-up the device from Sleep mode, when enabled.
While the comparator is powered up, higher Sleep
currents than shown in the power-down current
specification will occur. Each operational comparator
will consume additional current, as shown in the
comparator
consumption while in Sleep mode, turn off the
comparators (CM2:CM0 = 111) before entering Sleep.
If the device wakes up from Sleep, the contents of the
CMCON register are not affected.
20.8
A device Reset forces the CMCON register to its Reset
state, causing the comparator module to be in the Com-
parator Reset mode (CM2:CM0 = 000). This ensures
that all potential inputs are analog inputs. Device
current is minimized when analog inputs are present at
Reset time. The comparators are powered down during
the Reset interval.
D
D
EN
EN
CL
Q
Q
Comparator Operation
During Sleep
Effects of a Reset
specifications.
Comparator
© 2007 Microchip Technology Inc.
From
other
To
minimize
To RE1 or
RE2 pin
Bus
Data
Set
CMIF
bit
power