Datasheet

PICkit™ 3 Debug Express Lessons

FIGURE 3-61: CCPXCON: CCPX CONTROL REGISTER

For more information on Timer2 see Section 13.0 “Timer2 Module” of the

PIC18F45K20 Data Sheet (DS41303). More info on the CCP module PWM

functionality can be found in Section 15.0 “Capture/Compare/PWM (CCP) Module”,

and Section 15.4 “PWM Mode”.

3.12.3 Exploring the Lesson 12 Source Code

The PWM signal from the CCP1 module is normally output on the CCP1/RC2 pin.

However, this pin is not connected to any demo board LEDs. To output a signal on an

LED pin, the Enhanced CCP module (ECCP) on the PIC18F45K20 is utilized. This

functionality is selected in the upper 2 bits of CCP1CON (P1Mx), which are set to 0b01

so the modulated PWM signal appears on the P1D/RD7 which drives LED 7. No other

aspect of the enhanced PWM functionality is used; for more information see Section

16.0 “Enhanced Capture/Compare/Pwm (ECCP) Module”.

The first thing done in the lesson source code is to set PWM pin RD7 to an output.

TRISDbits.TRISD7 = 0;

Timer2 is then configured to generate the PWM period of 16 ms as discussed

previously in this lesson.

T2CON = 0b00000111;// Prescale = 1:16, timer on

PR2 = 249;// Timer 2 Period Register = 250 counts