Microchip Technology MA180025 Data Sheet
2010 Microchip Technology Inc.
DS39933D-page 299
PIC18F87J90 FAMILY
22.0 COMPARATOR MODULE
The analog comparator module contains two
comparators that can be configured in a variety of
ways. The inputs can be selected from the analog
inputs multiplexed with pins, RF1 through RF6, as well
as the on-chip voltage reference (see Section 23.0
“Comparator Voltage Reference Module”). The digi-
tal outputs (normal or inverted) are available at the pin
level and can also be read through the control register.
comparators that can be configured in a variety of
ways. The inputs can be selected from the analog
inputs multiplexed with pins, RF1 through RF6, as well
as the on-chip voltage reference (see Section 23.0
“Comparator Voltage Reference Module”). The digi-
tal outputs (normal or inverted) are available at the pin
level and can also be read through the control register.
The CMCON register (Register 22-1) selects the
comparator input and output configuration. Block
diagrams of the various comparator configurations are
shown in Figure 22-1.
comparator input and output configuration. Block
diagrams of the various comparator configurations are
shown in Figure 22-1.
REGISTER 22-1:
CMCON: COMPARATOR MODULE CONTROL REGISTER
R-0
R-0
R/W-0
R/W-0
R/W-0
R/W-1
R/W-1
R/W-1
C2OUT
C1OUT
C2INV
C1INV
CIS
CM2
CM1
CM0
bit 7
bit 0
Legend:
R = Readable bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
C2OUT: Comparator 2 Output bit
When C2INV = 0:
1
When C2INV = 0:
1
= C2 V
IN
+ > C2 V
IN
-
0
= C2 V
IN
+ < C2 V
IN
-
When C2INV = 1:
1
1
= C2 V
IN
+ < C2 V
IN
-
0
= C2 V
IN
+ > C2 V
IN
-
bit 6
C1OUT: Comparator 1 Output bit
When C1INV = 0:
1
When C1INV = 0:
1
= C1 V
IN
+ > C1 V
IN
-
0
= C1 V
IN
+ < C1 V
IN
-
When C1INV = 1:
1
1
= C1 V
IN
+ < C1 V
IN
-
0
= C1 V
IN
+ > C1 V
IN
-
bit 5
C2INV: Comparator 2 Output Inversion bit
1
= C2 output inverted
0
= C2 output not inverted
bit 4
C1INV: Comparator 1 Output Inversion bit
1
= C1 output inverted
0
= C1 output not inverted
bit 3
CIS: Comparator Input Switch bit
When CM<2:0> = 110:
1
When CM<2:0> = 110:
1
= C1 V
IN
- connects to RF5/AN10/CV
REF
/SEG23/C1INB
C2 V
IN
- connects to RF3/AN8/SEG21/C2INB
0
= C1 V
IN
- connects to RF6/AN11/SEG24/C1INA
C2 V
IN
- connects to RF4/AN9/SEG22/C2INA
bit 2-0
CM<2:0>: Comparator Mode bits
Figure 22-1 shows the Comparator modes and the CM<2:0> bit settings.
Figure 22-1 shows the Comparator modes and the CM<2:0> bit settings.