Datasheet

ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller SSOP 28 8-Bit 20 MHz I/O number 22

PIC16F87XA

DS39582C-page 68  2001-2013 Microchip Technology Inc.

8.3.3 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 8-3: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 20 MHz

TABLE 8-4: REGISTERS ASSOCIATED WITH CAPTURE, COMPARE AND TIMER1

PWM Frequency 1.22 kHz 4.88 kHz 19.53 kHz 78.12kHz 156.3 kHz 208.3 kHz

Timer Prescaler (1, 4, 16) 16 4 1 1 1 1

PR2 Value 0xFFh 0xFFh 0xFFh 0x3Fh 0x1Fh 0x17h

Maximum Resolution (bits) 10 10 10 8 7 5.5

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

INTCON GIE PEIE

TMR0IE INTE RBIE TMR0IF INTF RBIF 0000 000x 0000 000u

0Ch PIR1

PSPIF

(1)

ADIF RCIF TXIF 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

0Eh TMR1L Holding Register for the Least Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu

0Fh TMR1H Holding Register for the Most Significant Byte of the 16-bit TMR1 Register xxxx xxxx uuuu uuuu

10h T1CON

— — T1CKPS1 T1CKPS0 T1OSCEN T1SYNC TMR1CS TMR1ON --00 0000 --uu uuuu

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

1Bh CCPR2L Capture/Compare/PWM Register 2 (LSB) xxxx xxxx uuuu uuuu

1Ch CCPR2H Capture/Compare/PWM Register 2 (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 Capture and Timer1.

Note 1: The PSP is not implemented on 28-pin devices; always maintain these bits clear.