PIC16F87 Datasheet, PDF (123/214 Pages) Microchip Technology – 18/20/28-Pin Enhanced FLASH Microcontrollers with nanoWatt Technology

PIC16F87/88
13.0 COMPARATOR MODULE
The comparator module contains two analog
comparators. The inputs to the comparators are multi-
plexed with I/O port pins RA0 through RA3, while the
outputs are multiplexed to pins RA3 and RA4. The on-
chip Voltage Reference (Section 14.0 “Comparator
Voltage Reference Module”) can also be an input to
the comparators.
The CMCON register (Register 13-1) controls the com-
parator input and output multiplexers. A block diagram
of the various comparator configurations is shown in
Figure 13-1.
REGISTER 13-1:
CMCON REGISTER (ADDRESS 9Ch)
R-0
R-0
R/W-0 R/W-0
C2OUT C1OUT C2INV C1INV
bit 7
R/W-0
CIS
R/W-1
CM2
R/W-1
CM1
R/W-1
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 = 001:
1 = C1 VIN- connects to RA3
0 = C1 VIN- connects to RA0
When CM2:CM0 = 010:
1 = C1 VIN- connects to RA3
C2 VIN- connects to RA2
0 = C1 VIN- connects to RA0
C2 VIN- connects to RA1
CM<2:0>: Comparator Mode bits
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
 2003 Microchip Technology Inc.
Preliminary
DS30487B-page 121