Datasheet

PIC18F87J50 FAMILY
DS39775C-page 230 © 2009 Microchip Technology Inc.
The CCP1M1:CCP1M0 bits (CCP1CON<1:0>) allow
the user to choose whether the PWM output signals are
active-high or active-low for each pair of PWM output
pins (P1A/P1C and P1B/P1D). The PWM output
polarities must be selected before the PWM pins are
configured as outputs. Changing the polarity configura-
tion while the PWM pins are configured as outputs is
not recommended since it may result in damage to the
application circuits.
The P1A, P1B, P1C and P1D output latches may not be
in the proper states when the PWM module is initialized.
Enabling the PWM pins for output at the same time as
the ECCP1 module may cause damage to the applica-
tion circuit. The ECCP1 module must be enabled in the
proper output mode and complete a full PWM cycle
before configuring the PWM pins as outputs. The
completion of a full PWM cycle is indicated by the
TMR2IF bit being set as the second PWM period
begins.
FIGURE 18-10: PWM AUTO-SHUTDOWN (P1RSEN = 1, AUTO-RESTART ENABLED)
FIGURE 18-11: PWM AUTO-SHUTDOWN (P1RSEN = 0, AUTO-RESTART DISABLED)
Shutdown
PWM
ECCP1ASE bit
Activity
Event
Shutdown
Event Occurs
Shutdown
Event Clears
PWM
Resumes
Normal PWM
Start of
PWM Period
PWM Period
Shutdown
PWM
ECCP1ASE bit
Activity
Event
Shutdown
Event Occurs
Shutdown
Event Clears
PWM
Resumes
Normal PWM
Start of
PWM Period
ECCP1ASE
Cleared by
Firmware
PWM Period