PIC18F4580 Datasheet, PDF (259/484 Pages) Microchip Technology – 28/40/44-Pin Enhanced Flash Microcontrollers with ECAN Technology, 10-Bit A/D and nanoWatt Technology

PIC18F2480/2580/4480/4580
20.0 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 RA0 through RA5, as well as the
on-chip voltage reference (see Section 21.0
“Comparator Voltage Reference Module”). The digital
outputs (normal or inverted) are available at the pin level
and can also be read through the control register.
The CMCON register (Register 20-1) selects the
comparator input and output configuration. Block
diagrams of the various comparator configurations are
shown in Figure 20-1.
REGISTER 20-1:
CMCON: COMPARATOR CONTROL REGISTER
R-0
R-0
R/W-0 R/W-0 R/W-0
C2OUT C1OUT C2INV C1INV
CIS
bit 7
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/C1IN+
C2 VIN+ connects to RD2/PSP2/C2IN+
0 = C1 VIN- connects to RD1/PSP1/C1IN-
C2 VIN- connects to RD3/PSP3/C2IN-
CM2:CM0: Comparator Mode bits
Figure 20-1 shows the Comparator modes and the 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
 2004 Microchip Technology Inc.
Preliminary
DS39637A-page 257