PIC18F2480/2580/4480/4580
7. If auto-restart operation is required, set the
PRSEN bit (ECCP1DEL<7>).
17.4.9
SETUP FOR PWM OPERATION
The following steps should be taken when configuring
the ECCP module for PWM operation:
8. Configure and start TMR2:
• Clear the TMR2 interrupt flag bit by clearing
the TMR2IF bit (PIR1<1>).
1. Configure the PWM pins, P1A and P1B (and
P1C and P1D, if used), as inputs by setting the
corresponding TRIS bits.
• Set the TMR2 prescale value by loading the
T2CKPS bits (T2CON<1:0>).
2. Set the PWM period by loading the PR2 register.
• Enable Timer2 by setting the TMR2ON bit
(T2CON<2>).
3. Configure the ECCP1 module for the desired
PWM mode and configuration by loading the
ECCP1CON register with the appropriate
values:
9. Enable PWM outputs after a new PWM cycle
has started:
• Wait until TMRn overflows (TMRnIF bit is set).
• Select one of the available output
configurations and direction with the
EPWM1M<1:0> bits.
• Enable the ECCP1/P1A, P1B, P1C and/or
P1D pin outputs by clearing the respective
TRIS bits.
• Select the polarities of the PWM output
signals with the ECCP1M<3:0> bits.
• Clear the ECCPASE bit (ECCP1AS<7>).
4. Set the PWM duty cycle by loading the
ECCPR1L register and ECCP1CON<5:4> bits.
17.4.10 EFFECTS OF A RESET
Both Power-on Reset and subsequent Resets will force
all ports to Input mode and the CCP registers to their
Reset states.
5. For Half-Bridge Output mode, set the
dead-band delay by loading ECCP1DEL<6:0>
with the appropriate value.
6. If auto-shutdown operation is required, load the
ECCP1AS register:
This forces the Enhanced CCP module to reset to a
state compatible with the standard CCP module.
• Select the auto-shutdown sources using the
ECCPAS<2:0> bits.
• Select the shutdown states of the PWM
output pins using PSSAC<1:0> and
PSSBD<1:0> bits.
• Set the ECCPASE bit (ECCP1AS<7>).
• Configure the comparators using the CMCON
register.
• Configure the comparator inputs as analog
inputs.
© 2009 Microchip Technology Inc.
DS39637D-page 189
MICROCHIP [ MICROCHIP ]
