PIC18F258 Datasheet, PDF (247/384 Pages) Microchip Technology – High Performance, 28/40-Pin Enhanced FLASH Microcontrollers with CAN

PIC18FXX8
21.0 COMPARATOR MODULE
Note: The analog comparators are only available
on the PIC18F448 and PIC18F458.
The comparator module contains two analog compara-
tors. The inputs to the comparators are multiplexed
with the RD0 through RD3 pins. The On-Chip Voltage
Reference (Section 22.0) can also be an input to the
comparators.
REGISTER 21-1: CMCON REGISTER
R-0
C2OUT
bit 7
R-0
C1OUT
R/W-0
C2INV
The CMCON register, shown in Register 21-1, controls
the comparator input and output multiplexers. A block
diagram of the comparator is shown in Figure 21-1.
R/W-0
C1INV
R/W-0
CIS
R/W-0
CM2
R/W-0
CM1
R/W-0
CM0
bit 0
bit 7
bit 6
bit 5
bit 4
bit 3
bit 2-0
C2OUT: Comparator 2 Output bit
When C2INV = 0:
1 = C2 VIN+ > C2 VIN–
0 = C2 VIN+ < C2 VIN–
When C2INV = 1:
1 = C2 VIN+ < C2 VIN–
0 = C2 VIN+ > C2 VIN–
C1OUT: Comparator 1 Output bit
When C1INV = 0:
1 = C1 VIN+ > C1 VIN–
0 = C1 VIN+ < C1 VIN–
When C1INV = 1:
1 = C1 VIN+ < C1 VIN–
0 = C1 VIN+ > C1 VIN–
C2INV: Comparator 2 Output Inversion bit
1 = C2 output inverted
0 = C2 output not inverted
C1INV: Comparator 1 Output Inversion bit
1 = C1 output inverted
0 = C1 output not inverted
CIS: Comparator Input Switch bit
When CM2:CM0 = 110:
1 = C1 VIN- connects to RD0/PSP0
C2 VIN- connects to RD2/PSP2
0 = C1 VIN- connects to RD1/PSP1
C2 VIN- connects to RD3/PSP3
CM2:CM0: Comparator Mode bits
Figure 21-1 shows the Comparator modes and CM2:CM0 bit settings
Legend:
R = Readable bit
- n = Value at POR
W = Writable bit
’1’ = Bit is set
U = Unimplemented bit, read as ‘0’
’0’ = Bit is cleared x = Bit is unknown
 2002 Microchip Technology Inc.
Preliminary
DS41159B-page 245