PIC18F258 MICROCHIP [Microchip Technology], PIC18F258 Datasheet - Page 248

• Manufacturer Part Number: PIC18F258
• Description: High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18FXX8
21.1
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
FIGURE 21-1:
DS41159B-page 246
Comparators Reset (POR Default Value)
CM2:CM0 = 000
Two Independent Comparators
CM2:CM0 = 010
Two Common Reference Comparators
CM2:CM0 = 100
One Independent Comparator with Output
CM2:CM0 = 001
A = Analog Input, port reads zeros always
D = Digital Input
CIS (CMCON<3>) is the Comparator Input Switch
RD1/PSP1
RD0/PSP0
RD3/PSP3
RD2/PSP2
RD1/PSP1
RD0/PSP0
RE1/WR/AN6
RD3/PSP3
RD2/PSP2
RD1/PSP1
RD0/PSP0
RD3/PSP3
RD2/PSP2
RD1/PSP1
RD0/PSP0
RD3/PSP3
RD2/PSP2
Comparator Configuration
A
A
A
A
A
A
A
A
A
A
A
D
A
A
D
D
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
COMPARATOR I/O OPERATING MODES
-
+
-
+
-
+
-
+
-
+
-
+
-
+
-
+
C1
C2
C1
C2
C1
C2
C1
C2
Off
Off
C1OUT
C2OUT
C1OUT
C2OUT
C1OUT
Off
(Read as ’0’)
(Read as ’0’)
(Read as ’0’)
Preliminary
Two Common Reference Comparators with Outputs
CM2:CM0 = 101
Two Independent Comparators with Outputs
CM2:CM0 = 011
Comparators Off
CM2:CM0 = 111
Four Inputs Multiplexed to Two Comparators
CM2:CM0 = 110
RD1/PSP1
RD0/PSP0
RE1/WR/AN6
RD3/PSP3
RD2/PSP2
RE2/CS/AN7
RE1/WR/AN6
RD1/PSP1
RD0/PSP0
RD3/PSP3
RD2/PSP2
RE2/CS/AN7
RD1/PSP1
RD0/PSP0
RD3/PSP3
RD2/PSP2
RD1/PSP1
RD0/PSP0
RD3/PSP3
RD2/PSP2
mode is changed, the comparator output level may not
be valid for the specified mode change delay, shown in
Electrical Specifications (Section 27.0).
Note:
A
A
A
D
A
A
A
A
D
D
D
D
A
A
A
A
Comparator interrupts should be disabled
during a Comparator mode change.
Otherwise, a false interrupt may occur.
V
V
V
V
V
V
V
V
V
V
V
V
CIS = 0
CIS = 1
CIS = 0
CIS = 1
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
IN
-
+
-
+
-
+
-
+
-
+
-
+
C1
C2
C1
C2
C1
C2
2002 Microchip Technology Inc.
V
V
V
V
IN
IN
IN
IN
CV
-
+
-
+
REF
C1OUT
C2OUT
C1OUT
C2OUT
Off
Off
C1
C2
From V
(Read as ’0’)
(Read as ’0’)
REF
C1OUT
C2OUT
Module