Temperature Controlled rasPi 3B

[Gary E. Miller]

Yo Achim!

On Tue, 25 Apr 2017 12:34:52 +0200
Achim Gratz <Stromeko at nexgo.de> wrote:

> So, just before I left last week I managed to finally set up a
> temperature controller on my rasPi 3B using three sha512sum processes
> that get individually stopped and continued by the temperature control
> loop every 100ms to create a load between 0% and 300% and put it into
> another cardboard box and bubblewrap.

Cool.  Did you use ntpheat? 

>  I still have to add an integral
> term to the control loop in order to make the residual zero

ntpheatusb already has a full PID controller.  Did you look at that?

> and add a
> few other things to enable changing the setpoint while it's running
> and improve the logging,

If yu do so, could you send us patches for ntpheat?

> but it already converges to within 0.2K of
> the target temperature and keeps the 5 minutes average temperature to
> within 20mK or so (unless something else loads the cores for more
> than just a few seconds, like compiling a new NTPsec version).

I found that keeping the CPU chip temp stable was less important that\n
keeping ambient stable.  The XTAL is on the other side of the PCB
from the CPU.

I also found adding a fan to the box evened out the temps between
PCB top and bottom better.

> Since
> I was away I have data for nine days of uninterrupted and undisturbed
> performance:

Very nice.  What is the 'NTP Loop Offset'?  The Time offset?

How is the predicted frequency offset calculated?  Could that be patched
into ntpviz?

RGDS
GARY
---------------------------------------------------------------------------
Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
	gem at rellim.com  Tel:+1 541 382 8588

	    Veritas liberabit vos. -- Quid est veritas?
    "If you can’t measure it, you can’t improve it." - Lord Kelvin
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