BrewPi: Raspberry Pi and Arduino Powered Fermentation Chamber 96
For the homebrew hardware nerds out there who also homebrew beer: "BrewPi is an open source fermentation controller that runs on an Arduino (for now) and a Raspberry Pi. It can control your beer temperature with 0.1 degree precision, log temperature data in nice graphs and is fully configurable from a web interface."
Source code. The article has lots of photos and screenshots. The project involves rewiring the compressor's electrical connection through a PID controller, and includes both a fancy OLED display on the fridge and support for logging statistics and control over the web. If you've ever had the joy of gradually crash-cooling a lager (not too fast, not too slow), the software includes settings to effect gradual temperatures changes in the fermenting wort. Certainly fancier than a Johnson controller and a probe attached to a fermenter with a strip of insulating tape.
Re:Do the same with a handful of transistors (Score:3, Informative)
According to the comments here: http://hackaday.com/2012/10/01/brewpi-is-a-raspberry-pi-in-charge-of-beer-fermentation/
>The Pi is a bit too unstable to be trusted with direct control over the fermentation. The slave controller runs all the control algorithms, the Pi is for interfacing and data logging.
Re:Both an Arduino *and* a Raspberry Pi ? (Score:3, Informative)
Elco here,
The Arduino could by itself send some simple values to a server. It could not provide a fancy interface. The thermometer has ha 0.0625 resolution, a 0.5 deg absolute accuracy. I am filtering the temperature data and need the higher resolution for the control algorithm. If you don't filter, and your sensor jumps from 20.000 to 20.0625, what's the slope?
The program memory is full because of the 16 bit variables and that they are all configurable from the web interface. And no for brewing you don't NEED to control the temperature with 0.1 degree precision.
Re:Do the same with a handful of transistors (Score:2, Informative)
Elco here. The raspberry pi is easily fast enough, but it would crash on me sometimes. Just hang and require a reboot. A microcontroller just doesn't crash.
Re:Do the same with a handful of transistors (Score:5, Informative)
The Arduino does the temperature control (as that's what microcontrollers are good for) and the Pi is there to add a nice display and web server (as that's what a mini SBC is good for), seems like using the right tools for the right jobs to me. If you don't want a fancy display you could just use the Arduino part and skip the Pi.