Setup_timer_2 pwm for low frequencies

siddahuja · Joined: 09 Mar 2008 Posts: 1

Hi

Could anyone help me find the values for setting the timer 2 for PIC16F877A so that i can generate the pwm with the following characteristics:

Period: 15.95ms
Frequency: 62.7Hz
Duty Cycle: 10.7%

I am using a clock of 20MHz

Thanks in advance!
sid

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

This post tells you how to calculate the lowest PWM frequency
that you can get with a 20 MHz oscillator:
http://www.ccsinfo.com/forum/viewtopic.php?t=31625

John P · Joined: 17 Sep 2003 Posts: 331

Maybe it would be better just to generate two time intervals in turn, using time interrupts. First 10.7% of 15.95ms, then 89.3%, and repeat.

Of course, it depends on what else the processor has to do. If you have other things happening which absolutely must generate interrupts, this method won't work. But often there can be alternative approaches which rely on polling rather than interrupts.