PIC12F635/PIC16F636/639
7.4.3
COMPARATOR INPUT SWITCH
7.4
Comparator Control
The inverting input of the comparators may be switched
between two analog pins in the following modes:
The CMCON0 register (Register 7-1) provides access
to the following comparator features:
PIC12F635
• Mode selection
• Output state
• Output polarity
• Input switch
• CM<2:0> = 101
• CM<2:0> = 110
PIC16F636/639
• CM<2:0> = 001(Comparator C1 only)
7.4.1
COMPARATOR OUTPUT STATE
• CM<2:0> = 010(Comparators C1 and C2)
Each comparator state can always be read internally
via the CxOUT bit of the CMCON0 register. The com-
parator state may also be directed to the CxOUT pin in
the following modes:
In the above modes, both pins remain in Analog mode
regardless of which pin is selected as the input. The
CIS bit of the CMCON0 register controls the comparator
input switch.
PIC12F635
• CM<2:0> = 001
• CM<2:0> = 011
• CM<2:0> = 101
PIC16F636/639
• CM<2:0> = 110
When one of the above modes is selected, the
associated TRIS bit of the CxOUT pin must be cleared.
7.4.2
COMPARATOR OUTPUT POLARITY
Inverting the output of a comparator is functionally
equivalent to swapping the comparator inputs. The
polarity of a comparator output can be inverted by set-
ting the CXINV bit of the CMCON0 register. Clearing
CXINV results in a non-inverted output. A complete
table showing the output state versus input conditions
and the polarity bit is shown in Table 7-1.
TABLE 7-1:
OUTPUT STATE VS. INPUT
CONDITIONS
Input Conditions
CxINV
CxOUT
VIN- > VIN+
VIN- < VIN+
VIN- > VIN+
VIN- < VIN+
0
0
1
1
0
1
1
0
Note:
CxOUT refers to both the register bit and
output pin.
DS41232D-page 76
© 2007 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
