need audible pulse out that varies "on time"

[mister_e]

Yes, you could start an endless timer interrupt (let's say few milliseconds) in which you check your value, then start the HPWM and keep track of the required delay.

OR, enable the timer interrupt in your code, and assign a duration or flags for the HPWM.

[Jerson]

The way I would do it is to implement a soft PWM. I think it's been covered on this site already. Let a timer run in the background every mS. Give it a value for on time of the buzzer (0-1000mS) Every time the timer ticks, you can verify if the buzzer needs to be on or off. Now, all you have to do is give it a value from your mainline code.

[MUC]

jerson,

why soft and not HPWM? Honestly I'm not fully getting this...

Mark

[Jerson]

MUC

Frankly simply because I'm so used to it by now, I've never had to do the HPWM. I do a lot of temperature controllers with cycle times in the range of 1 to 30 seconds. So, ..... It's more a matter of personal taste.

Jerson