Manualsbrain.com
  1. Manuals
  2. Brands
  3. Microchip Technology
  4. DM164134
  5. Data Sheet

Microchip Technology DM164134 Data Sheet

Download
Page of 402
© 2006 Microchip Technology Inc.
DS41159E-page 249
PIC18FXX8
21.0
COMPARATOR MODULE
The comparator module contains two analog com-
parators. The inputs to the comparators are
multiplexed with the RD0 through RD3 pins. The on-chip
voltage reference (Section 22.0 “Comparator Voltage
Reference Module”) can also be an input to the
comparators.
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.
REGISTER 21-1:
CMCON: COMPARATOR CONTROL REGISTER 
           
Note:
The analog comparators are only
available on the PIC18F448 and
PIC18F458.
R-0
R-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
C2OUT
C1OUT
C2INV
C1INV
CIS
CM2
CM1
CM0
bit 7
bit 0
bit 7
C2OUT: Comparator 2 Output bit
When C2INV = 0:
1
 = C2 V
IN
+ > C2 V
IN
-
0
 = C2 V
IN
+ < C2 V
IN
-
When C2INV = 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
 = C1 V
IN
+ > C1 V
IN
-
0
 = C1 V
IN
+ < C1 V
IN
-
When C1INV = 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 CM2:CM0 = 110:
1
  = C1  V
IN
- connects to RD0/PSP0
C2 V
IN
- connects to RD2/PSP2
0
  = C1  V
IN
- connects to RD1/PSP1
C2 V
IN
- connects to RD3/PSP3
bit 2-0
CM2:CM0: Comparator Mode bits
Figure 21-1 shows the Comparator modes and CM2:CM0 bit settings.
Legend:
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