PIC16F627A Datasheet, PDF (64/168 Pages) Microchip Technology – FLASH-Based 8-Bit CMOS Microcontrollers

PIC16F627A/628A/648A
10.1 Comparator Configuration
There are eight modes of operation for the
comparators. The CMCON register is used to select
the mode. Figure 10-1 shows the eight possible
modes. The TRISA register controls the data direction
of the comparator pins for each mode. If the Compara-
tor mode is changed, the comparator output level may
not be valid for the specified mode change delay
shown in Table 17-2.
Note 1: Comparator interrupts should be disabled
during a Comparator mode change, other-
wise a false interrupt may occur.
2: Comparators can have an inverted out-
put. See Figure 10-3.
FIGURE 10-1:
COMPARATOR I/O OPERATING MODES
Comparators Reset (POR Default Value)
CM2:CM0 = 000
RA0/AN0
A
RA3/AN3/CMP1 ^A
VIN-
VIN+ ^C1
Comparators Off
CM2:CM0 = 111
RA0/AN0
D
Off (Read as '0') RA3/AN3/CMP1 ^D
VIN-
VIN+ ^C1
Off (Read as '0')
RA1/AN1
A
RA2/AN2/VREF ^A
VIN-
VIN+ ^C2
Two Independent Comparators
CM2:CM0 = 100
RA0/AN0
A
RA3/AN3/CMP1 ^A
VIN-
VIN+ ^C1
RA1/AN1
RA2/AN2/VREF
A
VIN-
A
VIN+ ^C2
Two Common Reference Comparators
CM2:CM0 = 011
RA0/AN0
A
RA3/AN3/CMP1 ^D
VIN-
VIN+ ^C1
Off (Read as '0')
C1VOUT
RA1/AN1
D
RA2/AN2/VREF ^D
VIN-
VIN+ ^C2
Off (Read as '0')
VSS
Four Inputs Multiplexed to Two Comparators
CM2:CM0 = 010
RA0/AN0
A
RA3/AN3/CMP1 ^A
CIS = 0 VIN-
CIS = 1 _{VIN+ C1}
C1VOUT
C2VOUT
RA1/AN1
A
RA2/AN2/VREF ^A
CIS = 0 VIN-
CIS = 1 _{VIN+ C2}
C2VOUT
C1VOUT
From VREF
Module
Two Common Reference Comparators with Outputs
CM2:CM0 = 110
RA0/AN0
A
RA3/AN3/CMP1 ^D
VIN-
VIN+ ^C1
C1VOUT
RA1/AN1
A
RA2/AN2/VREF ^A
VIN-
VIN+ ^C2
One Independent Comparator
CM2:CM0 = 101
RA0/AN0
D
RA3/AN3/CMP1 ^D
VIN-
VIN+ ^C1
VSS
RA1/AN1
A
RA2/AN2/VREF ^A
VIN-
VIN+ ^C2
C2VOUT
RA1/AN1
RA2/AN2/VREF
A
VIN-
A
VIN+ ^C2
C2VOUT
RA4/T0CKI/CMP2 ^{Open Drain}
Three Inputs Multiplexed to Two Comparators
CM2:CM0 = 001
Off (Read as '0')
RA0/AN0
A
RA3/AN3/CMP1 ^A
CIS = 0 VIN-
CIS = 1 _{VIN+ C1}
C1VOUT
C2VOUT
RA1/AN1
A
RA2/AN2/VREF ^A
VIN-
VIN+ ^C2
C2VOUT
A = Analog Input, port reads zeros always.
D = Digital Input.
CIS (CMCON<3>) is the Comparator Input Switch.
DS40044A-page 62
Preliminary
 2002 Microchip Technology Inc.