pic16f877a_pwmExample1.c

#include<pic16f877a.h>

void delay(int cnt) {
    while (cnt--);
}

int main() {
    char dutyCycle = 0;

    TRISC = 0x00;   // Configure PORTC as output(RC2-PWM1, RC1-PWM2)

    CCP1CON = 0x0F; // Select the PWM mode.
    PR2 = 100;      // Set the Cycle time to 100 for varying the duty cycle from 0-100
    CCPR1L = 50;    // By default set the dutyCycle to 50
    TMR2ON = 1;     //Start the Timer for PWM generation


    while (1) {
        for (dutyCycle = 0; dutyCycle < 100; dutyCycle++) // Keep increasing the dutyCyle to increase the brightness of LED
        {
            CCPR1L = dutyCycle;
            delay(10000);
        }

        for (dutyCycle = 100; dutyCycle > 0; dutyCycle--) // Keep reducing the dutyCyle to decrease the brightness of LED
        {
            CCPR1L = dutyCycle;
            delay(10000);
        }
    }
}