MCO <= 30Hz ?

[markgilson9]

Posted on July 12, 2012 at 18:32

I'm wondering if it's possible to generate a clock (or 1PPS) on the MCO pin?  I'm just not sure how far down you can divide this clock...  If this isn't feasible, is it possible to generate a 1PPS with the RTC?

[Tesla DeLorean]

Posted on July 12, 2012 at 19:02

Don't think so. Can you use a TIM output in PWM?

[markgilson9]

Posted on July 12, 2012 at 19:15

Ummm, if the STM32F4 can do that, then yes.  This doesn't really have to be a 50% duty cycle standard clock.  All I'm looking for is sub 30Hz pulses.  1PPS is desired, but multiple would be ok as well...I'll be driving the input to a frame sync pin on another part.  Would I be able to use PWM to generate such an external pulse at said rate?

[Tesla DeLorean]

Posted on July 12, 2012 at 19:23

Sure.

Assuming a 84 MHz, or 168 MHz input, set the prescaler to 42000-1, and then period to 2000-1 or 4000-1 respectively, and then set the width to a 100 or so, or 2000/2

Want finer granularity a prescaler of 4200-1, or some other factored combination.

[markgilson9]

Posted on July 12, 2012 at 19:27

Alright, I'll take a look at this.  As always, thanks clive!