PIC16F7X Datasheet, PDF (60/174 Pages) Microchip Technology – 28/40-Pin 8-Bit CMOS FLASH Microcontrollers

PIC16F7X
8.5.3 SETUP FOR PWM OPERATION
The following steps should be taken when configuring
the CCP module for PWM operation:
1. Set the PWM period by writing to the PR2 register.
2. Set the PWM duty cycle by writing to the
CCPR1L register and CCP1CON<5:4> bits.
3. Make the CCP1 pin an output by clearing the
TRISC<2> bit.
4. Set the TMR2 prescale value and enable Timer2
by writing to T2CON.
5. Configure the CCP1 module for PWM operation.
TABLE 8-4: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS (FOSC = 20 MHz)
PWM Frequency
Timer Prescale (1, 4, 16)
PR2 Value
Maximum Resolution (bits)
1.22 kHz
16
0xFF
10
4.88 kHz
4
0xFF
10
19.53 kHz
1
0xFF
10
78.12 kHz
1
0x3F
8
156.3 kHz
1
0x1F
7
208.3 kHz
1
0x17
5.5
TABLE 8-5: REGISTERS ASSOCIATED WITH PWM AND TIMER2
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, INTCON
10Bh,18Bh
0Ch
PIR1
GIE
PSPIF⁽¹⁾
PEIE
ADIF
TMR0IE
RCIF
INTE
TXIF
RBIE TMR0IF INTF RBIF 0000 000x 0000 000u
SSPIF CCP1IF TMR2IF TMR1IF 0000 0000 0000 0000
0Dh
PIR2
—
—
—
—
—
—
— CCP2IF ---- ---0 ---- ---0
8Ch
PIE1
PSPIE⁽¹⁾ ADIE
RCIE
TXIE SSPIE CCP1IE TMR2IE TMR1IE 0000 0000 0000 0000
8Dh
PIE2
—
—
—
—
—
—
— CCP2IE ---- ---0 ---- ---0
87h
TRISC PORTC Data Direction Register
1111 1111 1111 1111
11h
TMR2 Timer2 Module Register
0000 0000 0000 0000
92h
PR2
Timer2 Module Period Register
1111 1111 1111 1111
12h
T2CON
— TOUTPS3 TOUTPS2 TOUTPS1 TOUTPS0 TMR2ON T2CKPS1 T2CKPS0 -000 0000 -000 0000
15h
CCPR1L Capture/Compare/PWM Register1 (LSB)
xxxx xxxx uuuu uuuu
16h
CCPR1H Capture/Compare/PWM Register1 (MSB)
xxxx xxxx uuuu uuuu
17h
CCP1CON —
—
CCP1X CCP1Y CCP1M3 CCP1M2 CCP1M1 CCP1M0 --00 0000 --00 0000
1Bh
CCPR2L Capture/Compare/PWM Register2 (LSB)
xxxx xxxx uuuu uuuu
1Ch
CCPR2H Capture/Compare/PWM Register2 (MSB)
xxxx xxxx uuuu uuuu
1Dh
CCP2CON —
—
CCP2X CCP2Y CCP2M3 CCP2M2 CCP2M1 CCP2M0 --00 0000 --00 0000
Legend: x = unknown, u = unchanged, - = unimplemented, read as '0'. Shaded cells are not used by PWM and Timer2.
Note 1: Bits PSPIE and PSPIF are reserved on the PIC16F73/76; always maintain these bits clear.
DS30325B-page 58
 2002 Microchip Technology Inc.