Microchip Technology IC MCU FLASH 4K PIC16LF88-I/P DIP-18 MCP PIC16LF88-I/P 数据表
产品代码
PIC16LF88-I/P
2002-2013 Microchip Technology Inc.
DS30487D-page 85
PIC16F87/88
The maximum PWM resolution (bits) for a given PWM
frequency is given by the following formula.
frequency is given by the following formula.
EQUATION 9-3:
9.3.3
SETUP FOR PWM OPERATION
The following steps should be taken when configuring
the CCP module for PWM operation:
the CCP module for PWM operation:
1.
Set the PWM period by writing to the PR2
register.
register.
2.
Set the PWM duty cycle by writing to the
CCPR1L register and CCP1CON<5:4> bits.
CCPR1L register and CCP1CON<5:4> bits.
3.
Make the CCP1 pin an output by clearing the
TRISB<x> bit.
TRISB<x> bit.
4.
Set the TMR2 prescale value and enable Timer2
by writing to T2CON.
by writing to T2CON.
5.
Configure the CCP1 module for PWM operation.
TABLE 9-3:
EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 20 MHz
TABLE 9-4:
REGISTERS ASSOCIATED WITH PWM AND TIMER2
Note:
If the PWM duty cycle value is longer than
the PWM period, the CCP1 pin will not be
cleared.
the PWM period, the CCP1 pin will not be
cleared.
log
(
F
PWM
log(2)
F
OSC
)
bits
=
Resolution
Note:
The TRISB bit (0 or 3) is dependant upon
the setting of configuration bit 12
(CCPMX).
the setting of configuration bit 12
(CCPMX).
PWM Frequency
1.22 kHz
4.88 kHz
19.53 kHz
78.12 kHz
156.3 kHz
208.3 kHz
Timer Prescaler (1, 4, 16)
16
4
1
1
1
1
PR2 Value
0xFF
0xFF
0xFF
0x3F
0x1F
0x17
Maximum Resolution (bits)
10
10
10
8
7
6.6
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR, BOR
Value on
all other
Resets
0Bh,8Bh
10Bh,18Bh
10Bh,18Bh
INTCON
GIE
PEIE
TMR0IE
INT0IE
RBIE
TMR0IF
INT0IF
RBIF
0000 000x 0000 000u
0Ch
PIR1
—
ADIF
(1)
RCIF
TXIF
SSPIF
CCP1IF
TMR2IF
TMR1IF
-000 0000 -000 0000
8Ch
PIE1
—
ADIE
(1)
RCIE
TXIE
SSPIE
CCP1IE
TMR2IE
TMR1IE
-000 0000 -000 0000
86h
TRISB
PORTB Data Direction Register
1111 1111 1111 1111
11h
TMR2
Timer2 Module Register
0000 0000 0000 0000
92h
PR2
Timer2 Period Register
1111 1111 1111 1111
12h
T2CON
—
TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000
15h
CCPR1L
Capture/Compare/PWM Register 1 (LSB)
xxxx xxxx uuuu uuuu
16h
CCPR1H
Capture/Compare/PWM Register 1 (MSB)
xxxx xxxx uuuu uuuu
17h
CCP1CON
—
—
CCP1X
CCP1Y
CCP1M3 CCP1M2 CCP1M1
CCP1M0 --00 0000 --00 0000
Legend:
x
= unknown, u = unchanged, - = unimplemented, read as ‘0’. Shaded cells are not used by PWM and Timer2.
Note
1:
This bit is only implemented on the PIC16F88. The bit will read ‘0’ on the PIC16F87.