[SS2S-Main] Re: temperature controller with arduino

  • From: Nathan Asdourian <rawliquid@xxxxxxxxx>
  • To: sugarshot@xxxxxxxxxxxxx
  • Date: Sun, 29 Jun 2014 17:40:58 -0700

I'm a bit on the fence with the whole thing. On one hand ive had a
reasonably good time helping a guy in france develop and refine an arduino
plugin module for the home automation program homeseer. When I stumbled
upon his project, the core module was semi reliable but had connection
issues, used up enough of the available ram that the ide wasnt too happy,
and had horribly duplicated code eating up like 80% of the flash. I looked
at his sketch and without even really understanding all of it, I managed to
help him isolate the two pieces which function independantly so the
compiler knew which set of code to leave out, as well as an exhaustive
review of his almost sinful was of ram due to which datatypes he used and
just storage in general.

That said, it should be taken into consideration that you could get an
actual pid controller for around the same price as an arduino uno r3.
Granted that is direct from china or Taiwan, but really with the available
budget I dont think being picky is a reasonable thing. About the only thing
that could keep going with the arduino reasonable is if we(the people in
this conversation) are willing and able to donate most of the necessary
The way I see it, we would need an arduino board, uno being the lowest,
mega offers significantly more memory. Or possibly the due which is much
more powerful as it is 32bit.
Also needed are compatible thermocouples, I did see someplace you can get
stainless steel tubes that a ds18b20 slides right into, I just havent
checked on operating temps vs the temps you will be at.
I imagine a rtc module will be necessary otherwise you may as well base the
time on when your mother uses the restroom.
An sd card slot should be included to facilitate logging the various temps
and burner status. This will provide proof of the parameters and eliminate
the question of if a part was cooked right.

As for what I am prepared to offer up, here goes...
I saw there was already an offer from a someone to write the arduino code,
I can offer code review and collaboration, assuming your willing to put the
code up on githib so we can easily communicate back and forth on multiple
subjects without losing track of things.
Assuming that the ds18b20 is used, I can also relatively quickly set up a
test setup to validate the code and attempt to pinpoint any issues, which I
would do with my own hardware I already have or will purchase on my own so
no shipping  involved.
Hardware wise I can offer up a combo micro sd and sd adapter board, which
has a switch to select card type. I also have a spare rtc I can dig out.
Ds18b20's can be aquired for free via maxims samples program, you can order
up to 2 of each kind, and last time I did it, I think there were 5
different versions available, all mostly the same, a couple were surface
mount which makes using it as a probe difficult.
I can also offer up soldering if needed. I consider myself well above
average with an iron, and the fact I have a hakko fx-951 certainly doesnt
hurt any.

I think that about wraps it up for me, back to lurking unless its decided
to go the arduino route, in which case just let me know.
On Jun 29, 2014 3:53 PM, "Peter Johansson" <rockets4kids@xxxxxxxxx> wrote:

> On Sun, Jun 29, 2014 at 6:36 PM, Vicente Alvero Zambrano
> <vicente_alvero_14@xxxxxxxxxxx> wrote:
> > My idea is to use an old oven heater like the picture.
> > With respect to the PID controller, maybe it is cheaper to do it
> manually,
> > without writing code.
> One option to consider -- and an advantage to going with a homebrew
> solution -- is to simply read a configuration file containing the
> temperature profile and PID tunings over over the serial port.
> This way you get the maximal possible control with the minimal
> hardware cost and minimal software development time.
> -p.

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