Hallo,
Habe ursprünglich die frage auf englisch verfasst, auf Deutsch zu anzworten ist kein Problem. Benütze den C18 compiler von Microchip.
I have a problem generating consistent PWM outputs.
Specifically, the output duty cycle varies every time I call the SetDCPWM1() function in my code below. Upon checking the RC2/CCP1 pin with the Oscilloscope, the PWM period stays constant, but the duty cycle is different in the while()-loop every time called, although the argument is the same
More strangely, my RB4 output pin (which I use to Enable a H-Bridge Driver) after some seconds drops low - although its state shouldnt change in the while loop.
Anyone have any idea? I´m using an external 6MHz Quarz, each pin connected also in parallell with two 27pF connected to GND. The PIC is a PIC18F248.
#include <p18f248.h>
#include <stdlib.h>
#include <string.h>
#include <pwm.h>
#include <timers.h>
#include <delays.h>
#pragma config OSC = HS
#pragma config PWRT = ON
#pragma config BOR = OFF
#pragma config WDT = OFF
#pragma config LVP = OFF
#pragma code
void main(void)
{
OpenPWM1(0xf0);
OpenTimer2(T2_PS_1_1 & T2_POST_1_10 & TIMER_INT_OFF);
PORTC = 0; // Clear PORTC
TRISC = 0xdb; // Make RC2/CCP1 and RC5(remove later) outputs
LATB = 0x10; //0x10 = 00010000b = bit4 (RB4) of PORTB Register ON
TRISB = 0xef; //0xEF = 11101111h = bit4 (RB4) of TRISB sets Output
while (1)
{
Delay10KTCYx(255);
SetDCPWM1(600);
}
}
//END OF PROGRAM
