smoother pwm control

[cerr]

Hi There,

I'm looking for a way (if possible) to adjust the duty cycle for my pwm in a finer interval than 1%.
I'm running the pwm on a PIC16F883 with a 20MHz crystal. My timer2 (for the pwm) is configured like this

[PCM programmer]

This thread has an example of using the CCP in Compare mode to
do PWM with finer resolution:
http://www.ccsinfo.com/forum/viewtopic.php?t=44328

[Ttelmah]

But, not at this high speed. :(
PCM's solution gives more steps for a low frequency PWM, but doesn't help at 200KHz.
At 200KHz, you are going to have problems. You can get a little finer, by going to a CPU supporting 25MHz, or switching to a 18 chip with a PLL, and going to 40, or possibly even 64MHz (depending on the chip). However the big question is do you really need 200KHz?.
The step size, is cycles on the clock, so if you could go down to 100KHz, and 40Mhz, you would have 400steps available, against your current 100.

Best Wishes

[Mike Walne]

Answer the questions.

Why do you need better than 1% setting?
Why do you need 200kHz?
What you are trying to achieve?

Then we may be able to suggest sensible solutions.

Mike

P.S. 1% setting gives a max 0.5% error