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Automating my BBQ

Posted: Thu Jan 17, 2013 10:28 pm
by structor
The most fun projects are when two hobbies come together. I have been bbq-ing since quite a while but the last couple of years it has become more of a hobby. For more serious bbq-ing you start to prepare your meat at lower temperatures and thus the preperation times will automatically grow longer. To give an idea when you prepare pulled pork, sessions of more then twelve hours are fairly normal. During those preperations the temperature needs to be controlled fairly precisely. With most bbq's you control the temperature by opening and closing mechanical valves.
This can ofcourse not easily be automated but ofcourse there have been some clever guys that have figured out a manner howto do this. But those systems are fairly expensive, so I have decided to build up my own system using a couple of jeenodes.

The first jeenode the bbq-controller will have the task to measure and control the heat. The second jeenode (masternode) will acts as a gateway and will have a network card and acts as a gateway to pass along messages between the bbqcontroller and the server which will actually create graphs. The first idea was to 'host' the network part in my domotica software, but due to some interest from a bbq-forum I hang out I have decided to build a standalone webapplication for this.

Now some more details about the bbq-controller. The bbqcontroller will measure up to four probes using the analog ports on the jeenode. The probes are basically NTC's so a simple voltage divider is sufficient. One of the probes is the probe which will be placed on the grill and that temperature will be regulated to a configurable setpoint. But how to control the temperature for a bbq? Well this is fairly easy, first up you close up the regular airvents and the over one the vents you place a fan. The fan is also controlled by the jeenode using a mosfet. The jeenode will use PWM to control the fan faster or slower. The setpoint is then controlled using a technique called PID-tuning. This sounds very fancy, but once I started surfing around howto do this in detail, I found out that somebody already did this and place the complete source code on github so the bbqcontroller was created fairly quickly.

The only thing I added was the two way communication between controller and the server and I have refactored the sourcecode a bit so it suits my style a bit better.

Since pictures say more then a thousand words.

The masternode on the left, the bbqcontroller on the right:
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A close up shot of the measurement board of the controller:
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A calibration run cooling boiling water down, to get the steinhart coefficients for the probes:
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The fan mounted in it's housing and connected to the airvent of the bbq using water 'piping'.
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The first test run showing the complete setup, the fan can be shown below, two temperature probes are fed-in above. One is connected to a commercial temperure logger the second fed-in to my bbq-controller.
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Every bbq-session is now started with the definition what you will prepare and what the setpoint of the grill will be:
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During a session the temperature is completely controlled by the bbq-controller. This will periodically send the temperatures and fanspeed to the masternode, which will push the values to a webserver. The values will be then forwarded realtime to the webbrowser using signalr (using websockets or long polling depending of your browser). Realtime monitoring of the temperature is done using the gauges on the left and every now and the values are stored in db and a refresh of the XY-graph is forced (also using signalr). The graphing is done using Google Charting. In images instead of text:

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In the picture above I was preparing a so-called fatty, but since we got hungry (at 1 hour and 45 mins), I decided to jack up the temperature. Very funny when you can do that from inside your house using your ipad :D.

And now to show what kind of stuff takes these long preperation times, the following is called a 'procureur' weighing roughly 2-3 kilo's.
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And looks like this when prepared:
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And like this when you're about to eat it:
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To conclude I am very happy with this project, but for sure will miss the days camping around the entire night with a beer in my hand :D
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Thanx for watching.

Re: Automating my BBQ

Posted: Fri Jan 18, 2013 10:49 am
by AshaiRey
I'll take my hat of for you and bow deeply.
A very nice project indeed.
Thanks for sharing

Re: Automating my BBQ

Posted: Fri Jan 18, 2013 11:02 am
by sj3fk3
OH MY GAWD!

Only one question remains... When is the domoticaforum BBQ?

Posted: Sat Jan 19, 2013 3:02 pm
by DJF3
Great idea.. When is the BBQ?

Re: Automating my BBQ

Posted: Mon Apr 01, 2013 11:27 am
by vanisher
Hey Structor, is this the final version? And you have a kitlist available to build this Controller?

Re: Automating my BBQ

Posted: Mon Apr 01, 2013 12:40 pm
by structor
What is final ;) The controller is a modification from a well known controller called the heatermeter. I have been using it for a while now and it's stable. At the bbq-genootschap the first other forum member is creating it. I am thinking about creating prints for it, so that it will be easier to create.
You can read more about it at:
bbqgenootschap.nl/forum/index.php?topic ... pic=2554.0

I am currently busy with creating an android interface for it and i am thinking about extending the controller with a bluetooth interface, so that the phone can communicate directly to the controller.

Re: Automating my BBQ

Posted: Mon Apr 01, 2013 1:02 pm
by vanisher
I will have a look at the url. I already have a bunch of jeenodes running around attached to Domotiga. Sooooooooo, integration would be great :)

Re: Automating my BBQ

Posted: Mon Apr 01, 2013 2:35 pm
by structor
If you want to integrate on the server side / or need info / need the software please let me know.

Re: Automating my BBQ

Posted: Fri Jan 31, 2014 6:47 am
by thechad
I think I need to get working on this for my bbq.

I might include a webcam in the mix so i don't even have to go out to take a look!