PIC16F887-I/PT Microchip Technology Inc., PIC16F887-I/PT Datasheet - Page 130

• Manufacturer Part Number: PIC16F887-I/PT
• Description: MCU, 8-Bit, 8KW Flash, 368 RAM, 36 I/O, TQFP-44
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16F887-I/PT

• 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: 44-pin TFQP
• 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

PIC16F882/883/884/886/887
11.5
The PWM mode generates a Pulse-Width Modulated
signal on the CCPx pin. The duty cycle, period and
resolution are determined by the following registers:
• PR2
• T2CON
• CCPRxL
• CCPxCON
In Pulse-Width Modulation (PWM) mode, the CCP
module produces up to a 10-bit resolution PWM output
on the CCPx pin. Since the CCPx pin is multiplexed
with the PORT data latch, the TRIS for that pin must be
cleared to enable the CCPx pin output driver.
Figure 11-3 shows a simplified block diagram of PWM
operation.
Figure 11-4 shows a typical waveform of the PWM
signal.
For a step-by-step procedure on how to set up the CCP
module for PWM operation, see Section 11.5.7
“Setup for PWM Operation”.
FIGURE 11-3:
DS41291D-page 128
Note 1:
Note:
CCPRxH
Duty Cycle Registers
Comparator
2:
CCPRxL
PWM Mode
PR2
TMR2
Comparator
Clearing the CCPxCON register will
relinquish CCPx control of the CCPx pin.
The 8-bit timer TMR2 register is concatenated
with the 2-bit internal system clock (F
2 bits of the prescaler, to create the 10-bit time
base.
In PWM mode, CCPRxH is a read-only register.
(2)
(Slave)
(1)
SIMPLIFIED PWM BLOCK
DIAGRAM
Clear Timer2,
toggle CCPx pin and
latch duty cycle
CCPxCON<5:4>
S
R
Q
TRIS
OSC
CCPx
), or
Preliminary
The PWM output (Figure 11-4) has a time base
(period) and a time that the output stays high (duty
cycle).
FIGURE 11-4:
Pulse Width
TMR2 = 0
Period
CCP PWM OUTPUT
TMR2 = CCPRxL:CCPxCON<5:4>
© 2007 Microchip Technology Inc.
TMR2 = PR2