Hello,

I read in the datasheet that the equation for the pwm period is PWM period = [(PR2 + 1) * 4 * Tosc * PrescalerTimer2].

I need a 120Hz frequency (8.3ms period), but it seems I can't reach it. I'm using Fosc=16MHz, and by my calculations, the highest pwm period I can achieve is 1.024ms. Is that correct? Is there any way I can have 120Hz pwm frequency with this Fosc?

 

Here is a code calculator for PWM http://www.micro-examples.com/public/microex-navig/doc/097-pwm-calculator.html
It will show alternate frequencies to get that PWM freq.
Max.

 

Here is a code calculator for PWM http://www.micro-examples.com/public/microex-navig/doc/097-pwm-calculator.html
It will show alternate frequencies to get that PWM freq.
Max.

Neat. So according to website OP will need to use 2 MHz Fosc.

 

If you have to stick to that micro, then probably the sole way to go is reduce the Xtal frequency.

If you can select a different one, the 18F4431 for example, allows you to reach PWM lower than 50 Hz. The secret: in one of the peripheral it has an additional prescaler thta brigns everything down to what you need.