setting duty cycles using ccp1con

[gedza]

How do I set the pwm module to use the 8 msbs of the ccp1rl bits and ignore the 2lsbs in ccp1con

 

[bigdogguru]

In other words you want to take a 10-bit PWM duty cycle and turn it into an 8-bit PWM duty cycle?

Why?

 

[gedza]

My program is varying duty cycles taking them from a lookup tgable therefore it is difficult to change ccp1rl at the same time changing ccp1con and the signal is at 200khz therefore the resolution is to be about 6 bits so how do I set these in my program.

 

[bigdogguru]

One possibility is leaving the LSBs in CCP1CON set to zero, while changing only the eight MSBs in CCP1RL this would effectively reduce your PWM duty cycle resolution by a factor of 4.

This means your changes to the PWM duty cycle will by coarser, larger changes.

---------- Post added at 09:00 ---------- Previous post was at 08:51 ----------

Here's a thread discussing modification of PWM duty cycle:

PWM Duty Cycle

 

[gedza]

CAN YOU PLEASE HELP ME ON SINUSOIDAL PWM .Is the value of ccpr1l loaded by an interrupt service routine of tmr2 or there is need to use another timer . I want to get a 50hz sine wave therefore should I use tmr2 to change the duty cycle.how am I going to determine the 50Hz frequency in my code most preferebly in asm.My switching frequency is 200khz .

 

[bigdogguru]

Hi gedzak,

I'm working on a ASM program using interrupts to generate PWM.

Actually, I found some code from a previous project using PWM sinusoidal generation, so I modifying it to fit your needs. I'll also physically test the algorithm.

Quick question, by "...switching frequency is 200kHz", you mean the sampling frequency of PWM, correct?

 

[gedza]

Yes it is the frequencyis the sampling frequency.thanks