Microchip Technology MCP3421DM-WS Data Sheet
© 2009 Microchip Technology Inc.
DS39632E-page 275
PIC18F2455/2550/4455/4550
22.0 COMPARATOR MODULE
The analog comparator module contains two compara-
tors 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 volt-
age reference (see Section 23.0 “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.
tors 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 volt-
age reference (see Section 23.0 “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 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 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 = C2 V
When C2INV = 0:
1 = C2 V
IN
+ > C2 V
IN
-
0 = C2 V
IN
+ < C2 V
IN
-
When C2INV = 1:
1 = C2 V
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
When C1INV = 0:
1 = C1 V
IN
+ > C1 V
IN
-
0 = C1 V
IN
+ < C1 V
IN
-
When C1INV = 1:
1 = C1 V
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
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
1 = C1 output inverted
0 = C1 output not inverted
bit 3
CIS: Comparator Input Switch bit
When CM2:CM0 = 110:
1 = C1 V
When CM2:CM0 = 110:
1 = C1 V
IN
- connects to RA3/AN3/V
REF
+
C2 V
IN
- connects to RA2/AN2/V
REF
-/CV
REF
0 = C1 V
IN
- connects to RA0/AN0
C2 V
IN
- connects to RA1/AN1
bit 2-0
CM2:CM0: Comparator Mode bits
Figure 22-1 shows the Comparator modes and the CM2:CM0 bit settings.
Figure 22-1 shows the Comparator modes and the CM2:CM0 bit settings.