celegorn
Newbie level 5
Hello.
As the headline states, i am using PIC16F887 and i'm programming it with MPLAB, CCS compiler through Pickit 3. This is my code:
My understanding is, that the variable a (i.e. duty cycle) should not exceed the period constant. Also, when a=period the PWM should output its maximum, i.e. 5 volts.
That's not the case as i have witnessed. I tried measuring the output of the PWM and it got as high as 1.09V. Also, i tried to limit the increase of variable a higher than period:
Doing this and measuring the PWM output i managed to get about 3.3V and further increasing the limit (at about 470) i got to about 4.63V where it peaked and stayed for a second and then reset back to zero.
What am i missing? Why does it not give me the full voltage (5V) when the duty cycle is equal to the period? Have i understood the whole thing wrongly?
This is really puzzling me, please help, i would appreciate it a lot.
Thanks.
As the headline states, i am using PIC16F887 and i'm programming it with MPLAB, CCS compiler through Pickit 3. This is my code:
Code:
#include <16f887.h>
#use delay (clock=8000000)
unsigned int16 a,b;
#fuses HS,NOWDT,NOPROTECT,NOLVP
#define period 100
void main ()
{
a=1;
SET_TRIS_A(0);
SET_TRIS_C(0);
output_high(PIN_A5); // Arbitrary bit
output_high(PIN_A4); // Arbitrary bit
setup_ccp1(CCP_PWM); // Configure CCP1 as a PWM
setup_timer_2(T2_DIV_BY_4,period,1);
while(1)
{
if (a>=period) a=0;
set_pwm1_duty(a);
delay_ms(100);
a++;
output_toggle(PIN_A5);
}
}My understanding is, that the variable a (i.e. duty cycle) should not exceed the period constant. Also, when a=period the PWM should output its maximum, i.e. 5 volts.
That's not the case as i have witnessed. I tried measuring the output of the PWM and it got as high as 1.09V. Also, i tried to limit the increase of variable a higher than period:
Code:
if (a>=300 a=0;Doing this and measuring the PWM output i managed to get about 3.3V and further increasing the limit (at about 470) i got to about 4.63V where it peaked and stayed for a second and then reset back to zero.
What am i missing? Why does it not give me the full voltage (5V) when the duty cycle is equal to the period? Have i understood the whole thing wrongly?
This is really puzzling me, please help, i would appreciate it a lot.
Thanks.