
PIC18F6585/8585/6680/8680
DS30491C-page 260
2004 Microchip Technology Inc.
20.1
Comparator Configuration
There are eight modes of operation for the compara-
tors. The CMCON register is used to select these
The TRISF register controls the data direction of the
comparator pins for each mode. If the Comparator
mode is changed, the comparator output level may not
be valid for the specified mode change delay shown in
FIGURE 20-1:
COMPARATOR I/O OPERATING MODES
Note:
Comparator interrupts should be disabled
during
a
Comparator
mode
change.
Otherwise, a false interrupt may occur.
C1
RF6/AN11
VIN-
VIN+
RF5/AN10
Off (Read as ‘0’)
Comparators Reset (POR Default Value)
A
CM2:CM0 = 000
C2
RF4/AN9
VIN-
VIN+
RF3/AN8
Off (Read as ‘0’)
A
C1
RF6/AN11
VIN-
VIN+
RF5/AN10
C1OUT
Two Independent Comparators
A
CM2:CM0 = 010
C2
RF4/AN9
VIN-
VIN+
RF3/AN8
C2OUT
A
C1
RF6/AN11
VIN-
VIN+
RF5/AN10
C1OUT
Two Common Reference Comparators
A
CM2:CM0 = 100
C2
RF4/AN9
VIN-
VIN+
RF3/AN8
C2OUT
A
D
C2
RF4/AN9
VIN-
VIN+
RF3/AN8
Off (Read as ‘0’)
One Independent Comparator with Output
D
CM2:CM0 = 001
C1
RF6/AN11
VIN-
VIN+
RF5/AN10
C1OUT
A
C1
RF6/AN11
VIN-
VIN+
RF5/AN10
Off (Read as ‘0’)
Comparators Off
D
CM2:CM0 = 111
C2
RF4/AN9
VIN-
VIN+
RF3/AN8
Off (Read as ‘0’)
D
C1
RF6/AN11
VIN-
VIN+
RF5/AN10
C1OUT
Four Inputs Multiplexed to Two Comparators
A
CM2:CM0 = 110
C2
RF4/AN9
VIN-
VIN+
RF3/AN8
C2OUT
A
From VREF Module
CIS = 0
CIS = 1
CIS = 0
CIS = 1
C1
RF6/AN11
VIN-
VIN+
RF5/AN10
C1OUT
Two Common Reference Comparators with Outputs
A
CM2:CM0 = 101
C2
RF4/AN9
VIN-
VIN+
RF3/AN8
C2OUT
A
D
A = Analog Input, port reads zeros always
D = Digital Input
CIS (CMCON<3>) = Comparator Input Switch
CVREF
C1
RF6/AN11
VIN-
VIN+
RF5/AN10
C1OUT
Two Independent Comparators with Outputs
A
CM2:CM0 = 011
C2
RF4/AN9
VIN-
VIN+
RF3/AN8
C2OUT
A
RF2/AN7/C1OUT
RF1/AN6/C2OUT
RF2/AN7/C1OUT
RF1/AN6/C2OUT
RF2/AN7/C1OUT