PIC16F7X7
13.1
Comparator Configuration
There are eight modes of operation for the compara-
tors. The CMCON register is used to select these
modes. Figure 13-1 shows the eight possible modes.
The TRISA 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
the electrical specifications (Section
Note:
Comparator interrupts should be disabled
during a Comparator mode change.
Otherwise, a false interrupt may occur.
FIGURE 13-1:
Comparators Reset
CM2:CM0 =
000
RA0/AN0
A
COMPARATOR I/O OPERATING MODES
Comparators Off (POR Default Mode)
CM2:CM0 =
111
V
IN
-
V
IN
+
RA0/AN0
C1
Off
(Read as ‘0’)
D
V
IN
-
V
IN
+
RA3/AN3/
A
V
REF
+
RA3/AN3/
D
V
REF
+
C1
Off
(Read as ‘0’)
RA1/AN1
A
V
IN
-
V
IN
+
RA1/AN1
C2
Off
(Read as ‘0’)
D
V
IN
-
V
IN
+
RA2/AN2/
A
V
REF
-/CV
REF
RA2/AN2/
D
V
REF
-/CV
REF
C2
Off
(Read as
‘
0
’
)
Two Independent Comparators
CM2:CM0 =
010
RA0/AN0
A
V
IN
-
V
IN
+
Two Independent Comparators with Outputs
CM2:CM0 =
011
RA0/AN0
A
V
IN
-
V
IN
+
RA3/AN3/
A
V
REF
+
C1
C1OUT
RA3/AN3/
A
V
REF
+
C1
C1OUT
RA4/T0CKI/C1OUT
RA1/AN1
A
V
IN
-
V
IN
+
RA2/AN2/
A
V
REF
-/CV
REF
C2
C2OUT
RA1/AN1
A
V
IN
-
V
IN
+
RA2/AN2/
A
V
REF
-/CV
REF
C2
C2OUT
RA5/AN4/LVDIN/SS/C2OUT
Two Common Reference Comparators
CM2:CM0 =
100
RA0/AN0
A
V
IN
-
V
IN
+
Two Common Reference Comparators with Outputs
CM2:CM0 =
101
RA0/AN0
A
A
V
IN
-
V
IN
+
RA3/AN3/
A
V
REF
+
C1
C1OUT
RA3/AN3/
V
REF
+
C1
C1OUT
RA4/T0CKI/C1OUT
RA1/AN1
A
V
IN
-
V
IN
+
RA2/AN2/
D
V
REF
-/CV
REF
C2
C2OUT
RA1/AN1
A
V
IN
-
V
IN
+
D
RA2/AN2/
V
REF
-/CV
REF
C2
C2OUT
RA5/AN4/LVDIN/SS/C2OUT
One Independent Comparator with Output
CM2:CM0 =
001
RA0/AN0
A
V
IN
-
V
IN
+
Four Inputs Multiplexed to Two Comparators
CM2:CM0 =
110
RA0/AN0
A
CIS =
0
CIS =
1
V
IN
-
V
IN
+
RA3/AN3/
A
V
REF
+
C1
C1OUT
RA3/AN3/
A
V
REF
+
RA1/AN1
A
C1
C1OUT
RA4/T0CKI/C1OUT
D
RA1/AN1
V
IN
-
V
IN
+
RA2/AN2/
A
V
REF
-/CV
REF
C2
Off
(Read as ‘0’)
CIS =
0
CIS =
1
V
IN
-
V
IN
+
C2
C2OUT
RA2/AN2/
D
V
REF
-/CV
REF
CV
REF
From Comparator
V
REF
Module
D = Digital Input
CIS (CMCON<3>) is the Comparator Input Switch
A = Analog Input, port reads zeros always
DS30498C-page 162
2004 Microchip Technology Inc.
MICROCHIP [ MICROCHIP TECHNOLOGY ]
