PIC 100% PWM Duty Cycle Problem in MikroC

[M.Rehan]

At 100% duty Cycle PIC is not giving always high signal
Why?

How to get rid of this fault?

Can I edit default existing PWM library in MikroC?

PIC Used : 18f4550
Tool: MikroC Pro for PIC

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Code C - [expand]
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void main() 
{
   TRISC = 0 ;     // set PORTC as output
   PORTC = 0 ;
   PWM2_Init(1000);
   PWM2_Set_Duty(200);
  while(1)
  {
     PWM2_Start();
     Delay_ms (1000);
     PWM2_Set_Duty(255);   // 100% Duty Cycle
     Delay_ms (10000);
   }
}

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[KlausST]

Hi,

it may be that 100% is not possible with the setup.

0 = 0/256 duty cycle
1 = 1/256 duty cycle
...
255 = 255/256 duty cycle

Klaus

 

[M.Rehan]

https://download.mikroe.com/documents/compilers/mikroc/pic/help/pwm_library.htm

 

[KlausST]

Hi,

they say: (percent x 255) * 100

and they say
0 = 0% (obviously)
127 = 50% (if so, then 254 should be 100%, or 50% should be (exactely: 127.50) they rounded down to 127)
192 = 75% (is so, then 256 should be 100%, or 75% should be (exactely: 191.25) they now rounded up to 192)

You see their informations are not consistent.

****
I know two cases:
* 0 to 255 means 0/256 to 255/256 duty cycle (0 % duty cycle possible. 100% not possible)
* 0 to 255 means 1/256 to 256/256 duty cycle (0 % duty cycle not possible. 100% possible)

Klaus

- - - Updated - - -

Added:
btw: if you want to drive a half bridge or full bridge N-CH power stage with bootstrap supply, then a 100% duty cycle is not allowed.
So it´s good to have 255/256 duty cycle.

Klaus