PIC18LF4610T-I Datasheet, PDF (135/376 Pages) Microchip Technology – 28/40/44-Pin Flash Microcontrollers

PIC18F2X1X/4X1X
The CCPRxH register and a 2-bit internal latch are
used to double-buffer the PWM duty cycle. This
double-buffering is essential for glitchless PWM
operation.
When the CCPRxH and 2-bit latch match TMR2,
concatenated with an internal 2-bit Q clock or 2 bits of
the TMR2 prescaler, the CCPx pin is cleared.
The maximum PWM resolution (bits) for a given PWM
frequency is given by the equation:
EQUATION 14-3:
log
⎛
⎝
F--F--P^-O--W^{--S---CM---⎠⎞}
PWM Resolution (max) = -------l--o---g----₍--2----₎-------bits
Note:
If the PWM duty cycle value is longer than
the PWM period, the CCP2 pin will not be
cleared.
TABLE 14-4: EXAMPLE PWM FREQUENCIES AND RESOLUTIONS AT 40 MHz
PWM Frequency
2.44 kHz 9.77 kHz 39.06 kHz 156.25 kHz 312.50 kHz 416.67 kHz
Timer Prescaler (1, 4, 16)
16
4
1
1
1
1
PR2 Value
FFh
FFh
FFh
3Fh
1Fh
17h
Maximum Resolution (bits)
10
10
10
8
7
6.58
14.4.3 PWM AUTO-SHUTDOWN
(CCP1 ONLY)
The PWM auto-shutdown features of the Enhanced
CCP module are also available to CCP1 in 28-pin
devices. The operation of this feature is
discussed in detail in Section 15.4.7 “Enhanced
PWM Auto-Shutdown”.
Auto-shutdown features are not available for CCP2.
14.4.4 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
CCPRxL register and CCPxCON<5:4> bits.
3. Make the CCPx pin an output by clearing the
appropriate TRIS bit.
4. Set the TMR2 prescale value, then enable
Timer2 by writing to T2CON.
5. Configure the CCPx module for PWM operation.
© 2009 Microchip Technology Inc.
DS39636D-page 137