PIC16F872-I/SO Microchip Technology, PIC16F872-I/SO Datasheet - Page 50

• Manufacturer Part Number: PIC16F872-I/SO
• Description: IC MCU FLASH 2KX14 EE 28SOIC
• Manufacturer: Microchip Technology
• Series: PIC® 16Fr

Specifications of PIC16F872-I/SO

• Program Memory Type: FLASH
• Program Memory Size: 3.5KB (2K x 14)
• Package / Case: 28-SOIC (7.5mm Width)
• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: I²C, SPI
• Peripherals: Brown-out Detect/Reset, POR, PWM, WDT
• Number Of I /o: 22
• Eeprom Size: 64 x 8
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 5x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Processor Series: PIC16F
• Core: PIC
• Data Bus Width: 8 bit
• Data Ram Size: 128 B
• Interface Type: I2C/SPI/SSP
• Maximum Clock Frequency: 20 MHz
• Number Of Programmable I/os: 22
• Number Of Timers: 3
• Operating Supply Voltage: 4 V to 5.5 V
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: 52715-96, 52716-328, 52717-734
• Development Tools By Supplier: PG164130, DV164035, DV244005, DV164005, PG164120, ICE2000, DM163022
• Minimum Operating Temperature: - 40 C
• On-chip Adc: 5-ch x 10-bit
• Package: 28SOIC W
• Device Core: PIC
• Family Name: PIC16
• Maximum Speed: 20 MHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: XLT28SO-1 - SOCKET TRANSITION 28SOIC 300MIL309-1073 - ADAPTER 28-SOIC TO 28-SOIC309-1024 - ADAPTER 28-SOIC TO 28-DIP309-1023 - ADAPTER 28-SOIC TO 28-DIP
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

PIC16F872
8.3
In Pulse Width Modulation mode, the CCP1 pin pro-
duces up to a 10-bit resolution PWM output. Since the
CCP1 pin is multiplexed with the PORTC data latch, the
TRISC<2> bit must be cleared to make the CCP1 pin
an output.
Figure 8-3 shows a simplified block diagram of the
CCP module in PWM mode.
For a step-by-step procedure on how to set up the CCP
module for PWM operation, see Section 8.3.3.
FIGURE 8-3:
A PWM output (Figure 8-4) has a time-base (period)
and a time that the output stays high (duty cycle). The
frequency of the PWM is the inverse of the period
(1/period).
FIGURE 8-4:
DS30221C-page 48
Note 1:
Note:
CCPR1H (Slave)
CCPR1L
Comparator
Duty Cycle Registers
PR2
TMR2 = PR2
TMR2
Comparator
PWM Mode (PWM)
The 8-bit timer is concatenated with 2-bit internal Q
clock, or 2 bits of the prescaler to create 10-bit time-base.
Duty Cycle
Clearing the CCP1CON register will force
the CCP1 PWM output latch to the default
low level. This is not the PORTC I/O data
latch.
(Note 1)
Period
Clear Timer,
CCP1 pin and
latch D.C.
TMR2 = Duty Cycle
SIMPLIFIED PWM BLOCK
DIAGRAM
PWM OUTPUT
TMR2 = PR2
CCP1CON<5:4>
R
S
Q
TRISC<2>
RC2/CCP1
8.3.1
The PWM period is specified by writing to the PR2 reg-
ister. The PWM period can be calculated using the fol-
lowing formula:
PWM frequency is defined as 1 / [PWM period].
When TMR2 is equal to PR2, the following three events
occur on the next increment cycle:
• TMR2 is cleared
• The CCP1 pin is set (exception: if PWM duty
• The PWM duty cycle is latched from CCPR1L into
8.3.2
The PWM duty cycle is specified by writing to the
CCPR1L register and to the CCP1CON<5:4> bits. Up
to 10-bit resolution is available. The CCPR1L contains
the eight MSbs and the CCP1CON<5:4> contains the
two LSbs. This 10-bit value is represented by
CCPR1L:CCP1CON<5:4>. The following equation is
used to calculate the PWM duty cycle in time:
CCPR1L and CCP1CON<5:4> can be written to at any
time, but the duty cycle value is not latched into
CCPR1H until after a match between PR2 and TMR2
occurs (i.e., the period is complete). In PWM mode,
CCPR1H is a read only register.
The CCPR1H register and a 2-bit internal latch are
used to double buffer the PWM duty cycle. This double
buffering is essential for glitch-free PWM operation.
When the CCPR1H and 2-bit latch match TMR2, con-
catenated with an internal 2-bit Q clock or 2 bits of the
TMR2 prescaler, the CCP1 pin is cleared.
The maximum PWM resolution (bits) for a given PWM
frequency is given by the formula:
cycle = 0%, the CCP1 pin will not be set)
CCPR1H
Note:
Note:
PWM period = [(PR2) + 1] • 4 • T
PWM duty cycle = (CCPR1L:CCP1CON<5:4>) •
Resolution
The Timer2 postscaler (see Section 7.1) is
not used in the determination of the PWM
frequency. The postscaler could be used
to have a servo update rate at a different
frequency than the PWM output.
If the PWM duty cycle value is longer than
the PWM period, the CCP1 pin will not be
cleared.
PWM PERIOD
PWM DUTY CYCLE
(TMR2 prescale value)
=
© 2006 Microchip Technology Inc.
T
log
OSC
(
log(2)
• (TMR2 prescale value)
F
F
PWM
OSC
)
OSC
bits
•