need revise code for PWM AND I/O

[zhu177]

Hi Guys

the course work is required to design a project such that LED5 is driven by a PWM signal that causes the intensity to increase from a minimum to a maximum over 1 second then reduce back to zero over the next second repeats continuously’.
Even though I was try several times , the LED5 cannot reduce back to zero over next second. Please explain and give some idea to modify it.

cheers

#include <xc.h>


#pragma config WDTEN=OFF, FOSC=INTIO67,MCLRE=EXTMCLR,IESO=OFF, LVP=OFF

#define _XTAL_FREQ 4000000
void init(void);
void init(void)
    {
    OSCCON=0b01010010;//this to select internal osc at 4MHz
    ANSELC=0x00;//make PORTC digital I/O
    TRISC=0x03;//set appropriate data direction bits
    PORTC=0x00;//clear any PORTC outputs
    ANSELB=0x00;//make PORTB digital I/O
    TRISB=0x01;//set appropriate data direction bits (RB0 is input)
    PORTB=0x00;//clear PORTB outputs
    TRISA=0b00000001; //all outputs except RA0 analogue IP
    ANSELA=0x01; //make PORTA digital I/O except RA0 analogue
    PORTA=0x00; //clear all PORTA digital pins
    }
void init_PWM(void)
    {
    PR2=254;
    T2CON=0b00000101;//enables TMR2 hardware and prescalar to 4
    CCP1CON=0x00; //enables PWM
    CCPR1L=PR2/2; //sets equal ON/OFF time
    }


void main(void)
    {
init();
init_PWM();

    while(1)
        {
            {
             CCP1CON=0x0C;
            PR2=254;
                while(PR2>=0)
                    {
                    PR2=PR2--;
                    __delay_ms(2);
                    __delay_us(168);
                    __delay_us(168);
                    __delay_us(168);
                    __delay_us(168);
                    }              
            }
           
            {
             CCP1CON=0x0C;
            PR2=0;
                while(PR2<=254)
                    {
                    PR2=PR2++;
                    __delay_ms(2);
                    __delay_us(168);
                    __delay_us(168);
                    __delay_us(168);
                    __delay_us(168);
                }       
            }


    }
    }

 

[Ian Rogers]

Ok... What are your thoughts so far? Hopefully you know a programming language so we can assist you more..

Using a PWM module is relatively easy.... But you need to start the ball rolling..