PIC18F6X2X/8X2X
DS39612A-page 244
Advance Information
2003 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 Specifications.
FIGURE 21-1:
Comparators Reset (POR Default Value)
CM2:CM0 =
000
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
V
IN
-
V
IN
+
RF5/AN10
Off
(Read as ‘0’)
A
A
C2
RF4/AN9
V
IN
-
V
IN
+
RF3/AN8
Off
(Read as ‘0’)
A
A
C1
RF6/AN11
V
IN
-
V
IN
+
RF5/AN10
C1OUT
Two Independent Comparators
CM2:CM0 =
010
A
A
C2
RF4/AN9
V
IN
-
V
IN
+
RF3/AN8
C2OUT
A
A
C1
RF6/AN11
V
IN
-
V
IN
+
RF5/AN10
C1OUT
Two Common Reference Comparators
CM2:CM0 =
100
A
A
C2
RF4/AN9
V
IN
-
V
IN
+
RF3/AN8
C2OUT
A
D
C2
RF4/AN9
V
IN
-
V
IN
+
RF3/AN8
Off
(Read as ‘0’)
One Independent Comparator with Output
CM2:CM0 =
001
D
D
C1
RF6/AN11
V
IN
-
V
IN
+
RF5/AN10
C1OUT
A
A
C1
RF6/AN11
V
IN
-
V
IN
+
RF5/AN10
Off
(Read as ‘0’)
Comparators Off
CM2:CM0 =
111
D
D
C2
RF4/AN9
V
IN
-
V
IN
+
RF3/AN8
Off
(Read as ‘0’)
D
D
C1
RF6/AN11
V
IN
-
V
IN
+
RF5/AN10
C1OUT
Four Inputs Multiplexed to Two Comparators
CM2:CM0 =
110
A
A
C2
RF4/AN9
V
IN
-
V
IN
+
RF3/AN8
C2OUT
A
A
From V
REF
Module
CIS =
0
CIS =
1
CIS =
0
CIS =
1
C1
RF6/AN11
V
IN
-
V
IN
+
RF5/AN10
C1OUT
Two Common Reference Comparators with Outputs
CM2:CM0 =
101
A
A
C2
RF4/AN9
V
IN
-
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
V
IN
-
V
IN
+
RF5/AN10
C1OUT
Two Independent Comparators with Outputs
CM2:CM0 =
011
A
A
C2
RF4/AN9
V
IN
-
V
IN
+
RF3/AN8
C2OUT
A
A
RF2/AN7/C1OUT
RF1/AN6/C2OUT
RF2/AN7/C1OUT
RF1/AN6/C2OUT
RF2/AN7/C1OUT
