[OpenTRV-dev] Sous-vide cooking with Arduino aka very precise temperature control

[Damon Hart-Davis]

The core of the current simple algorithm (about 10 lines of PICAXE BASIC or AVR C) minimises valve movements to minimise noise/annoyance as well as conserving battery.  It also aims to minimise overshoot and energy wastage.

The current algorithm seems to work pretty well for the rooms that I've deployed it it (~0.3C temperature band) and for Bo's DHW, and it had tweakable parameters.

Which is not to say that things couldn't be better.

I can point out the current code if anyone would like to run their beady eye over it, of course!

Rgds

Damon



On 11 Jun 2013, at 11:52, Kevin Wood wrote:

> I built a controller for my home brew setup using an AVR implementing a
> simple PID controller. I'd be happy to share the code from.
> 
> I do wonder if a PID would the right for a TRV, though. PIDs are generally
> very good at minimising error but expensive in terms of the number of
> output adjustments the algorithm generates.
> 
> With a battery powered TRV I'd have thought we could afford quite a wide
> "dead zone" around the setting point before comfort is sacrificed, and in
> doing so, avoid too much motor activity, thus saving battery power.
> 
> I don't doubt that there are aspects of a PID algorithm that will help us,
> though.
> 
> Kevin
> 
>> Hi all,
>> 
>> Adafruit has a great example (with code) of controlling the temperature of
>> a rice cooker with an Arduino:
>> http://www.adafruit.com/blog/2013/06/10/sous-vide-controller-powered-by-arduino-the-sousviduino-the-adafruit-learning-system/
>> 
>> There may be some inspiration to get from the code, in particular the use
>> of the PID library.
>> 
>> Cheers,
>> 
>> Bruno
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