PIC16F628-20P Datasheet, PDF (56/170 Pages) Microchip Technology – FLASH-Based 8-Bit CMOS Microcontroller

PIC16F62X
9.1 Comparator Configuration
There are eight modes of operation for the
comparators. The CMCON register is used to select
the mode. Figure 9-1 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 Table 17-1.
Note:
Comparator interrupts should be disabled
during a Comparator mode change other-
wise a false interrupt may occur.
FIGURE 9-1:
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
RA2/AN2
A
VIN-
A
VIN+ ^C2
Two Independent Comparators
CM2:CM0 = 100
RA0/AN0
A
RA3/AN3/CMP1 ^A
VIN-
VIN+ ^C1
RA1/AN1
RA2/AN2
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
RA2/AN2
D
VIN-
D
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
RA2/AN2
A
CIS = 0 VIN-
A
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
RA2/AN2
A
VIN-
A
VIN+ ^C2
One Independent Comparator
CM2:CM0 = 101
RA0/AN0
D
RA3/AN3/CMP1 ^D
VIN-
VIN+ ^C1
VSS
RA1/AN1
RA2/AN2
A
VIN-
A
VIN+ ^C2
C2VOUT
RA1/AN1
A
RA2/AN2/CMP2 ^A
VIN-
VIN+ ^C2
C2VOUT
RA4/T0CKI/C20 ^{Open Drain}
Off (Read as '0')
Three Inputs Multiplexed to Two Comparators
CM2:CM0 = 001
This mode is disfunctional and has been corrected in the ‘A’
Revision Devices.
RA0/AN0
A
CIS = 0 VIN-
RA3/AN3/CMP1 ^A
CIS = 1
VIN+ ₊ ^C1
C1VOUT
C2VOUT
RA1/AN1
A
RA2/AN2
A
VIN-
VIN+ ₊ ^C2
C2VOUT
A = Analog Input, port reads zeros always.
D = Digital Input.
CIS (CMCON<3>) is the Comparator Input Switch.
DS40300C-page 54
Preliminary
 2003 Microchip Technology Inc.