Originally Posted by TomRep
I'd be interested in this just to monitor my temps etc. while brewing. Lets face it, my phone is up my butt 24/7, but I don't want to sit and stair at my control panel for the whole process.
That is the reason why I thought of doing this in the first place. I'd start heating up the strike water and walk away to do other things. I kind of knew how long it would take to heat up to temperature (about an hour) but many times I would find that I would overshoot it and then have to wait around to cool back down. Heating the water would also be the longest part of the process. (Took care of that problem with the 5500 watt heating element.) I first thought of using a laptop for control but did not want to lug that up and down the stairs so I thought a phone would be all that I really need.
I'm using a netburner for the microcontroller. The arduino has a better timebase. I currently count in 5 milliSec increments which is the best accuracy I could get without using timers. Getting the timing down for the one wire sensor was a PITA on the netburner. I don't recommend getting one for this application (although it works.). I doubt anyone has one on here. I think the arduino is better due to the low cost and ease of use but that is up to anyone who wants to use the app. I'll put together an interface specification for the app. This will allow anyone to design their own software on the microcontroller if they want such as trying out different PID algorithms (velocity vs. positional). I just put a very basic control loop together using the arduino PID library http://www.arduino.cc/playground/Code/PIDLibrary
. I update the PID once per cycle. For the app I can add control for pumps and stirrers and it should be easily expandable to control fermentation temperatures in freezers and refrigerators as well both ways (such as using a lightbulb to heat or turning on and off the freezer). I have a fridge that I was planning on eventually using this with. Don't have pumps yet. Wanted to start simple and gradually expand it. It would also be great to see what PID parameters are optimum for this application if people can post their plots saved on the phone with the parameters they used. This would make it easier for other people to tune their systems.