Program:
/* Calculations
* Fosc = 48MHz
*
* PWM Period = [(PR2) + 1] * 4 * TMR2 Prescale Value / Fosc
* PWM Period = 200us
* TMR2 Prescale = 16
* Hence, PR2 = 149 or 0x95
*
* Duty Cycle = 10% of 200us
* Duty Cycle = 20us
* Duty Cycle = (CCPR1L:CCP1CON<5:4>) * TMR2 Prescale Value / Fosc
* CCP1CON<5:4> = <1:1>
* Hence, CCPR1L = 15 or 0x0F
*/
//#include<p18f4550.h>
#include<xc.h>
//unsigned char count=0;
//bit TIMER,SPEED_UP;
void main(void)
{
unsigned int i;
TRISCbits.TRISC2 = 0; //CCP1 pin as output
CCP1CON = 0b00101100; //Select PWM mode; Duty cycle LSB CCP1CON<4:5> = <1:1>
T2CON = 0b00000010; //Prescalar = 16; Timer2 OFF
GIE=1;
TRISAbits.TRISA4=0;
while(1)
{
TMR2=0;
PR2 = 250;
CCPR1L = 2; //Duty cycle 1%
TMR2IF=0;
TMR2ON = 1; //Timer2 ON
for(int i=2;i<255;i+=50)
{
CCPR1L=i;
for(int j=0;j<1000;j++)
for(int k=0;k<10000;k++);
LATAbits.LATA4=~LATAbits.LATA4;
}
}
}
Output:
