PIC16F882/883/884/886/887
11.5.4
OPERATION IN SLEEP MODE
11.5.7
SETUP FOR PWM OPERATION
In Sleep mode, the TMR2 register will not increment
and the state of the module will not change. If the CCPx
pin is driving a value, it will continue to drive that value.
When the device wakes up, TMR2 will continue from its
previous state.
The following steps should be taken when configuring
the CCP module for PWM operation:
1. Disable the PWM pin (CCPx) output drivers as
an input by setting the associated TRIS bit.
2. Set the PWM period by loading the PR2 register.
3. Configure the CCP module for the PWM mode
by loading the CCPxCON register with the
appropriate values.
11.5.5
CHANGES IN SYSTEM CLOCK
FREQUENCY
The PWM frequency is derived from the system clock
frequency. Any changes in the system clock frequency
will result in changes to the PWM frequency. See
Section 4.0 “Oscillator Module (With Fail-Safe
Clock Monitor)” for additional details.
4. Set the PWM duty cycle by loading the CCPRxL
register and DCxB<1:0> bits of the CCPxCON
register.
5. Configure and start Timer2:
• Clear the TMR2IF interrupt flag bit of the
PIR1 register.
11.5.6
EFFECTS OF RESET
• Set the Timer2 prescale value by loading the
T2CKPS bits of the T2CON register.
Any Reset will force all ports to Input mode and the
CCP registers to their Reset states.
• Enable Timer2 by setting the TMR2ON bit of
the T2CON register.
6. Enable PWM output after a new PWM cycle has
started:
• Wait until Timer2 overflows (TMR2IF bit of
the PIR1 register is set).
• Enable the CCPx pin output driver by clearing
the associated TRIS bit.
© 2007 Microchip Technology Inc.
Preliminary
DS41291D-page 131
MICROCHIP [ MICROCHIP ]
