PIC16F887-E/P Microchip Technology Inc., PIC16F887-E/P Datasheet - Page 87

• Manufacturer Part Number: PIC16F887-E/P
• Description: 40 PIN, 14KB FLASH, 368 RAM, 36 I/O, PDIP
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F887-E/P

• A/d Inputs: 14-Channel, 10-Bit
• Comparators: 2
• Cpu Speed: 5 MIPS
• Eeprom Memory: 256 Bytes
• Frequency: 20 MHz
• Input Output: 35
• Interface: I2C/SPI/USART
• Memory Type: Flash
• Number Of Bits: 8
• Package Type: 40-pin PDIP
• Programmable Memory: 14K Bytes
• Ram Size: 368 Bytes
• Resistance, Drain To Source On: Bytes
• Serial Interface: MSSP or EUSART
• Speed: 20 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

8.2
Each
Configuration register: CM1CON0 for Comparator C1
and CM2CON0 for Comparator C2. In addition,
Comparator C2 has a second control register,
CM2CON1, for controlling the interaction with Timer1 and
simultaneous reading of both comparator outputs.
The CM1CON0 and CM2CON0 registers (see Registers
8-1 and 8-2, respectively) contain the control and Status
bits for the following:
• Enable
• Input selection
• Reference selection
• Output selection
• Output polarity
8.2.1
Setting the CxON bit of the CMxCON0 register enables
the comparator for operation. Clearing the CxON bit
disables the comparator resulting in minimum current
consumption.
8.2.2
The CxCH<1:0> bits of the CMxCON0 register direct
one of four analog input pins to the comparator
inverting input.
8.2.3
Setting the CxR bit of the CMxCON0 register directs an
internal voltage reference or an analog input pin to the
non-inverting
Section 8.10 “Comparator Voltage Reference” for
more information on the internal voltage reference
module.
8.2.4
The output of the comparator can be monitored by
reading either the CxOUT bit of the CMxCON0 register
or the MCxOUT bit of the CM2CON1 register. In order
to make the output available for an external connection,
the following conditions must be true:
• CxOE bit of the CMxCON0 register must be set
• Corresponding TRIS bit must be cleared
• CxON bit of the CMxCON0 register must be set
© 2008 Microchip Technology Inc.
Note:
comparator
Comparator Control
COMPARATOR ENABLE
COMPARATOR OUTPUT
COMPARATOR INPUT SELECTION
To use CxIN+ and CxIN- pins as analog
inputs, the appropriate bits must be set in
the ANSEL and ANSELH registers and the
corresponding TRIS bits must also be set
to disable the output drivers.
COMPARATOR REFERENCE
SELECTION
SELECTION
input
has
of
a
the
separate
comparator.
control
PIC16F882/883/884/886/887
See
and
8.2.5
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 CxPOL bit of the CMxCON0 register.
Clearing the CxPOL bit results in a non-inverted output.
Table 8-1 shows the output state versus input
conditions, including polarity control.
TABLE 8-1:
8.3
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
comparator differs from the settling time of the voltage
reference. Therefore, both of these times must be
considered when determining the total response time
to a comparator input change. See the Comparator and
Voltage Reference specifications in Section 17.0
“Electrical Specifications” for more details.
Input Condition
CxV
CxV
CxV
CxV
Note 1: The CxOE bit overrides the PORT data
IN
IN
IN
IN
- > CxV
- < CxV
- > CxV
- < CxV
2: The internal output of the comparator is
Comparator Response Time
COMPARATOR OUTPUT POLARITY
latch. Setting the CxON has no impact on
the port override.
latched with each instruction cycle.
Unless otherwise specified, external
outputs are not latched.
IN
IN
IN
IN
+
+
+
+
COMPARATOR OUTPUT
STATE VS. INPUT
CONDITIONS
CxPOL
0
0
1
1
DS41291E-page 85
CxOUT
0
1
1
0