Microchip Technology DM164134 Fiche De Données
PIC18FXX8
DS41159E-page 250
© 2006 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 TRISD register controls the data direction of the
comparator pins for each mode. If the Comparator
tors. The CMCON register is used to select these
modes. Figure 21-1 shows the eight possible modes.
The TRISD 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”.
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.
during a Comparator mode change;
otherwise, a false interrupt may occur.
C1
RD1/PSP1
V
IN
-
V
IN
+
Off
(Read as ‘0’)
Comparators Reset (POR Default Value)
A
A
CM2:CM0 = 000
C2
RD3/PSP3
V
IN
-
V
IN
+
RD2/PSP2
Off
(Read as ‘0’)
A
A
C1
RD1/PSP1
V
IN
-
V
IN
+
RD0/PSP0
C1OUT
Two Independent Comparators
A
A
CM2:CM0 = 010
C2
RD3/PSP3
V
IN
-
V
IN
+
RD2/PSP2
C2OUT
A
A
C1
RD1/PSP1
V
IN
-
V
IN
+
RD0/PSP0
C1OUT
Two Common Reference Comparators
A
A
CM2:CM0 = 100
C2
RD3/PSP3
V
IN
-
V
IN
+
RD2/PSP2
C2OUT
A
D
C2
RD3/PSP3
V
IN
-
V
IN
+
RD2/PSP2
Off
(Read as ‘0’)
One Independent Comparator with Output
D
D
CM2:CM0 = 001
C1
RD1/PSP1
V
IN
-
V
IN
+
RD0/PSP0
C1OUT
A
A
C1
RD1/PSP1
V
IN
-
V
IN
+
RD0/PSP0
Off
(Read as ‘0’)
Comparators Off
D
D
CM2:CM0 = 111
C2
RD3/PSP3
V
IN
-
V
IN
+
RD2/PSP2
Off
(Read as ‘0’)
D
D
C1
RD1/PSP1
V
IN
-
V
IN
+
RD0/PSP0
C1OUT
Four Inputs Multiplexed to Two Comparators
A
A
CM2:CM0 = 110
C2
RD3/PSP3
V
IN
-
V
IN
+
RD2/PSP2
C2OUT
A
A
From V
REF
Module
CIS = 0
CIS = 1
CIS = 1
CIS = 0
CIS = 1
CIS = 1
C1
RD1/PSP1
V
IN
-
V
IN
+
RD0/PSP0
C1OUT
Two Common Reference Comparators with Outputs
A
A
CM2:CM0 = 101
C2
RD3/PSP3
V
IN
-
V
IN
+
RD2/PSP2
C2OUT
A
D
A = Analog Input, port reads zeros always
D = Digital Input
CIS (CMCON<3>) is the Comparator Input Switch
D = Digital Input
CIS (CMCON<3>) is the Comparator Input Switch
CV
REF
C1
RD1/PSP1
V
IN
-
V
IN
+
RD0/PSP0
C1OUT
Two Independent Comparators with Outputs
A
A
CM2:CM0 = 011
C2
RD3/PSP3
V
IN
-
V
IN
+
RD2/PSP2
C2OUT
A
A
RE1/AN6/WR/C1OUT
RE2/AN7/CS/C2OUT
RE1/AN6/WR/
RE2/AN7/CS/C2OUT
RE1/AN6/WR/C1OUT
RD0/PSP0
C1OUT