Datasheet

PIC18F8722 FAMILY
DS39646C-page 282 © 2008 Microchip Technology Inc.
22.1 Comparator Configuration
There are eight modes of operation for the compara-
tors, shown in Figure 22-1. Bits CM<2:0> 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 28.0 “Electrical Characteristics”.
FIGURE 22-1: 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-
V
IN+
RF5/AN10/
Off (Read as ‘0’)
Comparators Reset
A
A
CM<2:0> = 000
C2
RF4/AN9
VIN-
V
IN+
RF3/AN8
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*
RF6/AN11
RF5/AN10
RF4/AN9
RF3/AN8
RF2/AN7/C1OUT*
RF1/AN6/C2OUT*
RF2/AN7/
* Setting the TRISF<2:1> bits will disable the comparator outputs by configuring the pins as inputs.
CV
REF
RF6/AN11
RF5/AN10/
RF4/AN9
RF3/AN8
CV
REF
RF6/AN11
RF5/AN10/
RF4/AN9
RF3/AN8
CV
REF
RF6/AN11
RF5/AN10/
RF4/AN9
RF3/AN8
CVREF
RF6/AN11
RF5/AN10/
RF4/AN9
RF3/AN8
CV
REF
RF2/AN7/
RF6/AN11
RF5/AN10/
RF4/AN9
RF3/AN8
CV
REF
RF6/AN11
RF5/AN10/
CV
REF
RF4/AN9
RF3/AN8
C1OUT*
C1OUT*