PIC18F2220/2320/4220/4320
FIGURE 20-1:
COMPARATOR I/O OPERATING MODES
Comparators RESET
Comparators Off (POR Default Value)
CM<2:0> = 000
CM<2:0> = 111
D
D
VIN-
VIN-
RA0/AN0
RA0/AN0
Off (Read as ‘0’)
Off (Read as ‘0’)
Off (Read as ‘0’)
Off (Read as ‘0’)
C1
C2
C1
C2
VIN+
VIN+
D
D
RA3/AN3/
VREF+
RA3/AN3/
VREF+
D
D
D
VIN-
VIN-
RA1/AN1
RA2/AN2/
RA1/AN1
VIN+
VIN+
D
RA2/AN2/
VREF-/CVREF
VREF-/CVREF
Two Independent Comparators with Outputs
CM<2:0> = 011
Two Independent Comparators
CM<2:0> = 010
A
VIN-
A
VIN-
RA0/AN0
RA0/AN0
C1OUT
C2OUT
C1
VIN+
A
C1OUT
C2OUT
C1
C2
VIN+
RA3/AN3/
VREF+
A
RA3/AN3/
VREF+
(1)
RA4/T0CKI/C1OUT
A
A
VIN-
RA1/AN1
RA2/AN2/
A
VIN-
RA1/AN1
RA2/AN2/
VIN+
C2
VIN+
A
VREF-/CVREF
VREF-/CVREF
(1)
RA5/AN4/SS/LVDIN/C2OUT
Two Common Reference Comparators
Two Common Reference Comparators with Outputs
CM<2:0> = 100
CM<2:0> = 101
A
A
A
VIN-
VIN-
RA0/AN0
RA0/AN0
C1OUT
C2OUT
C1OUT
C1
C2
C1
C2
VIN+
VIN+
A
RA3/AN3/
VREF+
RA3/AN3/
VREF+
(1)
RA4/T0CKI/C1OUT
A
D
VIN-
RA1/AN1
RA2/AN2/
A
D
VIN-
VIN+
VIN+
RA1/AN1
C2OUT
VREF-/CVREF
RA2/AN2/
VREF-/CVREF
(1)
RA5/AN4/SS/LVDIN/C2OUT
Four Inputs Multiplexed to Two Comparators
One Independent Comparator with Output
CM<2:0> = 110
CM<2:0> = 001
A
A
A
VIN-
RA0/AN0
RA0/AN0
CIS = 0
CIS = 1
VIN-
A
C1OUT
C1
C2
VIN+
RA3/AN3/
VREF+
C1OUT
C1
C2
RA3/AN3/
VREF+
VIN+
A
A
(1)
RA4/T0CKI/C1OUT
RA1/AN1
RA2/AN2/
VIN-
CIS = 0
CIS = 1
C2OUT
VIN+
D
D
VIN-
RA1/AN1
RA2/AN2/
VREF-/CVREF
CVROE = 0
CVROE = 1
Off (Read as ‘0’)
VIN+
CVREF
From VREF Module
VREF-/CVREF
(2)
A = Analog Input, port reads zeros always, overrides TRISA bit
D = Digital Input.
.
CIS (CMCON<3>) is the Comparator Input Switch; CVROE (CVRCON<6>) is the Voltage Reference Output Switch.
Note 1: RA4 must be configured as an output pin in TRISA<4> when used to output C1OUT. RA5 ignores TRISA<5> when
used as an output for C2OUT.
2: Mode 110 is exception. Comparator input pins obey TRISA bits.
DS39599C-page 222
2003 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
