Bad fan interaction with alarm


 

Bryan Mayland

TVWBB Hall of Fame
Has anyone noticed that while an alarm is ringing, the fan ceases to function properly? Well it does! I noticed this today when adding the ability to control a damper servo instead of a fan.

Technical details: the Arduino tone code that rings the alarm always uses TIMER2 regardless of which pin the alarm is connected to, instead of the hardware PWM. It changes the mode of the hardware PWM that coincidentally runs the fan. Dangit, I was going to fiddle with that hardware PWM!

So a warning: don't let your alarm go off unattended or you will certainly lose control of the pit temperature. When it stops beeping, things go back to normal control.

This will be fixed in the next version... I think.
 
Yeah, took me long enough right? I've got the webui and configuration all done, but I'm seeing some strangeness where it works for about 1.5 seconds then doesn't for 500ms then works. Clearly something's not _quite_ right so as soon as I work that out we're good to go.

Also in this version is optional additional PID information that might help with tuning. Add up the values and it gives you the fan speed, but maybe it will be useful to see where the numbers come into play.
 

 

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