[Noisebridge-discuss] can you write a PID loop for humidistat in Arduino

[Jake]

Hello mushroom fans (not the spinning kind)

I have stepped up to make this arduino-based humidity controller for the 
noisebridge mushroom project.  I have hooked up the SHT15 humidity (and 
temperature) sensor to the arduino, and i'm getting readings of 
temperature and humidity.

I will now attach a relay to the arduino, and make it so that it can 
control the relay from a pin.  That relay will be wired to an AC socket so 
that the humidifier above the mushroom closet can be activated by the 
arduino.

The goal is to maintain the specified humidity inside the mushroom closet. 
When it gets too low, the humidifier turns on.

I understand we need a PID loop, which stands for Period Interval Delta or 
something like that.  Basically a software loop which reads the humidity 
and decides when to turn the relay on and off to achieve a smooth 
humidity-regulating action.

Here is an arduino PID library discussion (it's already written)
http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1226431507

and here's the arduino sketch which reads the humidity/temperature sensor 
(and just displays it out the serial port)
http://wiring.org.co/learning/basics/humiditytemperaturesht15.html

if you are a good programmer and would like to help the mushroom 
cultivation happening at noisebridge (and elsewhere) please write to me 
indicating your interest in doing the software for this project.

thanks!
-jake