PIC18LF2X_13 Datasheet, PDF (202/560 Pages) Microchip Technology – PIC18(L)F2X/45K50 USB Flash MCU Product Brief

PIC18(L)F2X/4XK22
14.4.8
SETUP FOR ECCP PWM
OPERATION USING ECCP1 AND
TIMER2
The following steps should be taken when configuring
the ECCP1 module for PWM operation using Timer2:
1. Configure the PWM pins to be used (P1A, P1B,
P1C, and P1D):
• Configure PWM outputs to be used as inputs
by setting the corresponding TRIS bits. This
prevents spurious outputs during setup.
• Set the PSTR1CON bits for each PWM
output to be used.
2. Select Timer2 as the period timer by configuring
CCPTMR0 register bits C1TSEL<1:0> = ‘00’.
3. Set the PWM period by loading the PR2 register.
4. Configure auto-shutdown as OFF or select the
source with the CCP1AS<2:0> bits of the
ECCP1AS register.
5. Configure the auto-shutdown sources as
needed:
• Configure each comparator used.
• Configure the comparator inputs as analog.
• Configure the FLT0 input pin and clear
ANSB0.
6. Force a shutdown condition (OFF included):
• Configure safe starting output levels by
setting the default shutdown drive states with
the PSS1AC<1:0> and PSS1BD<1:0> bits of
the ECCP1AS register.
• Clear the P1RSEN bit of the PWM1CON
register.
• Set the CCP1AS bit of the ECCP1AS
register.
7. Configure the ECCP1 module for the desired
PWM mode and configuration by loading the
CCP1CON register with the appropriate values:
• Select one of the available output configura-
tions and direction with the P1M<1:0> bits.
• Select the polarities of the PWM output
signals with the CCP1M<3:0> bits.
8. Set the 10-bit PWM duty cycle:
• Load the eight MSbs into the CCPR1L
register.
• Load the two LSbs into the DC<1:0> bits of
the CCP1CON register.
9. For Half-Bridge Output mode, set the dead-
band delay by loading P1DC<6:0> bits of the
PWM1CON register with the appropriate value.
10. Configure and start TMR2:
• Set the TMR2 prescale value by loading the
T2CKPS bits of the T2CON register.
• Start Timer2 by setting the TMR2ON bit.
11. Enable the ECCP1/P1A, P1B, P1C and/or P1D
pin outputs by clearing the respective TRIS bits.
12. Start the PWM:
• If shutdown auto-restart is used, then set the
P1RSEN bit of the PWM1CON register.
• If shutdown auto-restart is not used, then
clear the CCP1ASE bit of the ECCP1AS
register.
DS41412F-page 202
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