PIC12F609T-I/P View Datasheet(PDF) - Microchip Technology
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PIC12F609T-I/P Datasheet PDF : 212 Pages
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PIC12F609/615/617/12HV609/615
9.3 Comparator Control
The comparator has two control and Configuration
registers: CMCON0 and CMCON1. The CMCON1
register is used for controlling the interaction with
Timer1 and simultaneously reading the comparator
output.
The CMCON0 register (Register 9-1) contain the
control and Status bits for the following:
• Enable
• Input selection
• Reference selection
• Output selection
• Output polarity
9.3.1 COMPARATOR ENABLE
Setting the CMON bit of the CMCON0 register enables
the comparator for operation. Clearing the CMON bit
disables the comparator for minimum current
consumption.
9.3.2 COMPARATOR INPUT SELECTION
The CMCH bit of the CMCON0 register directs one of
four analog input pins to the comparator inverting input.
Note:
To use CIN+ and CIN- pins as analog
inputs, the appropriate bits must be set in
the ANSEL register and the corresponding
TRIS bits must also be set to disable the
output drivers.
9.3.3
COMPARATOR REFERENCE
SELECTION
Setting the CMR bit of the CMxCON0 register directs
an internal voltage reference or an analog input pin to
the non-inverting input of the comparator. See
Section 9.10 “Comparator Voltage Reference” for
more information on the internal voltage reference
module.
9.3.4
COMPARATOR OUTPUT
SELECTION
The output of the comparator can be monitored by
reading either the COUT bit of the CMCON0 register. In
order to make the output available for an external
connection, the following conditions must be true:
• CMOE bit of the CMxCON0 register must be set
• Corresponding TRIS bit must be cleared
• CMON bit of the CMCON0 register must be set.
Note 1: The CMOE bit overrides the PORT data
latch. Setting the CMON has no impact
on the port override.
2: The internal output of the comparator is
latched with each instruction cycle.
Unless otherwise specified, external
outputs are not latched.
9.3.5 COMPARATOR OUTPUT POLARITY
Inverting the output of the comparator is functionally
equivalent to swapping the comparator inputs. The
polarity of the comparator output can be inverted by
setting the CMPOL bit of the CMCON0 register. Clear-
ing CMPOL results in a non-inverted output. A com-
plete table showing the output state versus input
conditions and the polarity bit is shown in Table 9-1.
TABLE 9-1: OUTPUT STATE VS. INPUT
CONDITIONS
Input Conditions
CMPOL
COUT
CMVIN- > CMVIN+
0
0
CMVIN- < CMVIN+
0
1
CMVIN- > CMVIN+
1
1
CMVIN- < CMVIN+
1
0
Note: COUT refers to both the register bit and
output pin.
9.4 Comparator Response Time
The comparator output is indeterminate for a period of
time after the change of an input source or the selection
of a new reference voltage. This period is referred to as
the response time. The response time of the compara-
tor differs from the settling time of the voltage refer-
ence. Therefore, both of these times must be
considered when determining the total response time
to a comparator input change. See Section 16.0
“Electrical Specifications” for more details.
2010 Microchip Technology Inc.
DS41302D-page 69
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