Datasheet

PIC18F87J72 FAMILY
DS39979A-page 294 Preliminary  2010 Microchip Technology Inc.
23.1 Comparator Configuration
There are eight modes of operation for the compara-
tors, shown in Figure 23-1. The CM<2:0> bits of the
CMCON register are used to select these modes. 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
Section 29.0 “Electrical Characteristics”.
FIGURE 23-1: COMPARATOR I/O OPERATING MODES
Note: Comparator interrupts should be disabled
during a Comparator mode change;
otherwise, a false interrupt may occur.
C1
VIN-
V
IN+
Off (Read as ‘0’)
Comparator Outputs Disabled
A
A
CM<2:0> = 000
C2
VIN-
V
IN+
Off (Read as ‘0’)
A
A
C1
VIN-
V
IN+
C1OUT
Two Independent Comparators
A
A
CM<2:0> = 010
C2
VIN-
V
IN+
C2OUT
A
A
C1
VIN-
V
IN+
C1OUT
Two Common Reference Comparators
A
A
CM<2:0> = 100
C2
VIN-
V
IN+
C2OUT
A
D
C2
VIN-
V
IN+
Off (Read as ‘0’)
One Independent Comparator with Output
D
D
CM<2:0> = 001
C1
VIN-
V
IN+
C1OUT
A
A
C1
VIN-
V
IN+
Off (Read as ‘0’)
Comparators Off (POR Default Value)
D
D
CM<2:0> = 111
C2
VIN-
V
IN+
Off (Read as ‘0’)
D
D
C1
VIN-
V
IN+
C1OUT
Four Inputs Multiplexed to Two Comparators
A
A
CM<2:0> = 110
C2
VIN-
V
IN+
C2OUT
A
A
From VREF module
CIS = 0
CIS = 1
CIS = 0
CIS = 1
C1
VIN-
V
IN+
C1OUT
Two Common Reference Comparators with Outputs
A
A
CM<2:0> = 101
C2
VIN-
V
IN+
C2OUT
A
D
A = Analog Input, port reads zeros always D = Digital Input CIS (CMCON<3>) is the Comparator Input Switch
CV
REF
C1
VIN-
V
IN+
C1OUT
Two Independent Comparators with Outputs
A
A
CM<2:0> = 011
C2
VIN-
V
IN+
C2OUT
A
A
RF1/AN6/C2OUT*/SEG19
RF2/AN7/C1OUT*/SEG20
* Setting the TRISF<2:1> bits will disable the comparator outputs by configuring the pins as inputs.
C1INA
C1INB
C2INA
C2INB
C1INB
C2INA
C2INB
C1INA
C1INA
C1INB
C2INA
RF2/AN7/C1OUT*/SEG20
RF1/AN6/C2OUT*/SEG19
RF2/AN7/C1OUT*/
SEG20
C1INA
C1INB
C2INA
C2INB
C1INA
C1INB
C2INA
C2INB
C1INA
C1INB
C2INA
C2INB
C1INA
C1INB
C2INA
C2INB
C1INA
C1INB
C2INA
C2INB
C2INB