Designing a Brew Chamber Controller (Part 2)

In the previous post we discussed what a brew chamber was, why we needed to control the temperature of the fermentation, and why I decided to use a Beaglebone Black (BBB) as my controller over a commercial digital temperature controller sold online.

Lets go over the reasons I choose the BBB over a commercial unit and put them in order of importance so we can see what we need in what order to build the project.  I've also added some more details as we build this list into our project design specification list.  Feel free to reorganize these as needed for your project.

THE BARE BONES REQUIREMENTS

1. Monitor ambient brew chamber air temperature
2. Turn on heating if needed
3. Turn on cooling if needed

SELECTING AND AUTOMATING THE PROCESS

1. Ability to select different fermentation processes depending on what we are making
2. Automate the fermentation process
• warmer start temperature to quickly optimize yeast colony size
• gradual cooling to optimum fermentation temperatures
• cold crash cycle when ferment is complete (requires a freezer)
• lager cycle if needed for style of beer (requires a freezer)
3. Network access (SSH, WWW and/or VNC for GUI) to the controller
• Private access for control of the process
• Public access for monitoring the process 
4. Alarm system sends texts/emails/tweets etc. 
5. MySQL database to track history/store yeast statistics etc.

OTHER THINGS TO MONITOR

1. Monitor fermentation vessel temperature
• Chart vessel/chamber temperature differential
2. Web cam for visual monitoring
3. CO2 off gassing
• Monitor rate of fermentation
• Determine when fermentation is complete
4. Monitor  power consumption
5. Monitor keg pressures
6. Monitor external/room temperature 
7. Monitor humidity (still not sure on this)

LOCAL INPUT GUI DEVICE

1. Local LCD touchscreen GUI (doubles the expense but gives a nice professional finishing touch)

If you know anything about setting/attaining goals then you may be familiar with the SMART goal method.  Goals should be Specific, Measurable, Attainable, Realistic, and Time bound. As we develop the project specifications we'll turn the project specifications list into SMART goals.

In the next post we'll start on the bare bones requirements. If this is all you want your brew chamber to accomplish I recommend purchasing a digital temperature controller online and using that instead.

If you want more out of your controller then check back for the next post where we'll actually use the BBB and a few discrete components and build a working mockup of our basic temperature controller.

If you want to follow along with the design and experimentation then you may be purchasing discrete components over many purchases thus increasing shipping costs.  If you want to wait until there is a viable Bill of Materials (BoM) and save on shipping costs that is fine also, you can build your project later once a viable BoM is developed.

Things you'll need for the next session:

1. Beaglebone Black  (any Beaglebone will probably work if you have one already - no need to purchase the Black version)
2. Thermistors (I have a 503 - or an actual temperature sensor which I will be purchasing several of later)
3. Thermistor datasheet (found online usually - maybe on the thermistor packaging if available)
4. Resistor to match your thermistor 10K to 50K ohms (not required if you use a temp sensor)
5. Red LED
6. Green LED
7. 2 - 1K resistor to limit current to the LED (saves your BBB from damage)
8. Solder-less Breadboard to place listed components
9. Jumper wire assortment
10. Read over the Introduction post and once you obtain your BBB accomplish the tasks listed there.

See you soon.