Datasheet

PIC18F6525/6621/8525/8621
DS39612C-page 244  2003-2013 Microchip Technology Inc.
21.1 Comparator Configuration
There are eight modes of operation for the compara-
tors. The CMCON register is used to select these
modes. Figure 21-1 shows the eight possible 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 27.0 “Electrical Characteristics”.
FIGURE 21-1: 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 (POR Default Value)
A
A
CM2:CM0 = 000
C2
RF4/AN9
VIN-
V
IN+
RF3/AN8
Off
(Read as ‘0’)
A
A
C1
RF6/AN11
VIN-
V
IN+
RF5/AN10/
C1OUT
Two Independent Comparators
A
A
CM2:CM0 = 010
C2
RF4/AN9
VIN-
V
IN+
RF3/AN8
C2OUT
A
A
C1
RF6/AN11
VIN-
V
IN+
RF5/AN10/
C1OUT
Two Common Reference Comparators
A
A
CM2:CM0 = 100
C2
RF4/AN9
VIN-
V
IN+
RF3/AN8
C2OUT
A
D
C2
RF4/AN9
VIN-
V
IN+
RF3/AN8
Off
(Read as ‘0’)
One Independent Comparator with Output
D
D
CM2:CM0 = 001
C1
RF6/AN11
VIN-
V
IN+
RF5/AN10/
C1OUT
A
A
C1
RF6/AN11
VIN-
V
IN+
RF5/AN10/
Off
(Read as ‘0’)
Comparators Off
D
D
CM2:CM0 = 111
C2
RF4/AN9
VIN-
V
IN+
RF3/AN8
Off
(Read as ‘0’)
D
D
C1
RF6/AN11
VIN-
V
IN+
RF5/AN10/
C1OUT
Four Inputs Multiplexed to Two Comparators
A
A
CM2:CM0 = 110
C2
RF4/AN9
VIN-
V
IN+
RF3/AN8
C2OUT
A
A
From VREF Module
CIS = 0
CIS = 1
CIS = 0
CIS = 1
C1
RF6/AN11
VIN-
V
IN+
RF5/AN10/
C1OUT
Two Common Reference Comparators with Outputs
A
A
CM2:CM0 = 101
C2
RF4/AN9
VIN-
V
IN+
RF3/AN8
C2OUT
A
D
A = Analog Input, port reads zeros always D = Digital Input CIS (CMCON<3>) is the Comparator Input Switch
CV
REF
C1
RF6/AN11
VIN-
V
IN+
RF5/AN10/
C1OUT
Two Independent Comparators with Outputs
A
A
CM2:CM0 = 011
C2
RF4/AN9
VIN-
V
IN+
RF3/AN8
C2OUT
A
A
RF2/AN7/C1OUT
RF1/AN6/C2OUT
RF2/AN7/C1OUT
RF1/AN6/C2OUT
RF2/AN7/C1OUT
CVREF
CVREF
CVREF
CVREF
CVREF
CVREF
CVREF
CVREF