Build Your Own BBQ Controller (w/Wifi)

[Drunk_J]

FYI, do we have anyone on the board interested in developing their own Wifi server BBQ controller and software? That way we would have complete control over features and functions.

I started out researching a better way to communicate from the computer to the BBQ Guru CyberQ and stumbled upon Arduino microcontrollers. There are loads of groups out there developing all sorts of neat applications for these little devices. They have also developed plenty of software librarys to run on these microcontrollers. So I purchased one along with a USB host controller shield (a shield is an additional board that plugs into the base Arduino board to add different functions to it).

http://www.arduino.cc/
http://www.amazon.com/Arduino-UNO-board ... B004CG4CN4
http://www.sparkfun.com/products/9947

Anyway, after more research I found a group of coffee roaster folks that had developed their own shield board which added thermocouples to the Arduino and had written PID & monitoring software for the purpose of controlling their roasters. Didn't take much from that to think it would be great to modify it for a KK and have a single controller that does everything I want, not even needing the CyberQ.

http://www.homeroasters.org/php/forum/v ... post_28017

http://www.mlgp-llc.com/arduino/public/arduino-pcb.html
http://code.google.com/p/tc4-shield/
http://www.sparkfun.com/products/9954
http://www.adafruit.com/index.php?main_ ... cts_id=271

I have purchased everything above (except Wifi board - that will be last) and have a working model running their software. I also modified their code library written for TypeK thermocouple to work with the standard Guru TC which is TypeT. I am looking for anyone interested in starting up a similar project as the coffee roaster guys, except for grilling. The Arduino language is based on C/C++.

-=J

[linuxwrangler]

I've played with the Arduino I got at Maker Faire a year ago but haven't done much practical with it, yet. There was an Arduino intro class at Ace Monster Toys last week but my schedule didn't allow getting to it. Sounds like a controller would be a good Arduino project, though.

[Amphoran]

Deej,
Would it be difficult to add the capacity to use RTDs? They're much more stable over time than any thermocouple.
cheers,
Mike

[DennisLinkletter]

Deej,
Would it be difficult to add the capacity to use RTDs? They're much more stable over time than any thermocouple.
cheers,
Mike

Thermocouples vs RTDs

[Drunk_J]

The issue with RTD is going to be the interface board (signal amplification to get the resolution needed for accuracy). I have not run across anyone with an Arduino RTD shield. Now thermistors could be used directly with the main arduino board, but you would be limited by the number. And I typically have not had great luck with cheaply made thermistor probes.

So being these guys developed a very nice TC board (and offer it for sale) and all the existing software, seems that would be a good way to go. Not to mention, change the term strips out for phone plugs which makes it completely Guru plug compatible. They also have developed the LCD board which has 4 buttons and 3 leds on it connected by IC2 (so it does not tie up the Arduino I/Os). Check out the pics of the full unit in their google code page....pretty nice.

Since we are talking about controlling a grill and not nuclear fission (fyi, all the reactors I have seen use TCs at the bottom of the vessel), TCs should be just fine to use. Not to mention cheap, easy and sturdy. The Guru folks have used them on all their controllers and with results verified by Whizzy, are pretty darn accurate for the purpose we use them. Faster TC response might also be helpful with open lid detect since you need to see a sharp temp drop over a very short time.

-=J

[Amphoran]

Yeah, TCs are probably fine for a cooking application.
I had to go to RTD's in the software controlled still I've been building for a large client, because we really need 0.1 deg C precision AND accuracy in order to adjust power or reflux quickly and keep the column in equilibrium as the boiler depletes.
I'm currently using a NI backbone, industrial strength, but very spendy. I was hoping that I might find something that would do the job in the open source community.
Cheers,
Mike

[Drunk_J]

I've played with the Arduino I got at Maker Faire a year ago but haven't done much practical with it, yet. There was an Arduino intro class at Ace Monster Toys last week but my schedule didn't allow getting to it. Sounds like a controller would be a good Arduino project, though.

Agreed! For myself, it is a learning platform for C/C++ (yes, my last programming class taught Fortran, Pascal, Cobol, Basic...so way behind the times). But at least the basic process is still there (plus I develop Filemaker databases which helps a little). Luckily with the internet, it is so easy to find a wealth of knowledge, resources and free programs to learn with. FYI, all software for Arduino is free and it also works with Arduino clones.

I already have several BBQ controllers, but thought it would be cool to have something developed by a group of BBQ folks, for us. Everything being open source and non profit would mean anyone can build it, tweak it for their own needs and share with the group. I am always amazed at all the cool toys and methods for use people can think up. And with a like minded end use, we all benefit. So hopefully, there will be some interest.

-=J

[Drunk_J]

Yeah, TCs are probably fine for a cooking application.
I had to go to RTD's in the software controlled still I've been building for a large client, because we really need 0.1 deg C precision AND accuracy in order to adjust power or reflux quickly and keep the column in equilibrium as the boiler depletes.
I'm currently using a NI backbone, industrial strength, but very spendy. I was hoping that I might find something that would do the job in the open source community.
Cheers,
Mike

Yeah, I completely agree in your application since temp ranges are so tight. There are posts out there of people who have used Arduino for RTD, but unfortunately I did not come across any premade shields.

Just curious, Moore used to make a tiny PLC called the Equation Station that easily handled RTDs. From what I remember, they were pretty cheap as I have one. Though you still have to buy their software to program the device. Used to deal with PLC and DCS systems once upon a time.

-=J

[jdbower]

The idea of a crowd-sourced temperature controller is kind of neat. Especially since I now think I need to rewrite stoker_mon, anyway. The Stoker seems a little underpowered for my technique of using a JSON polling method - it was fine with a fan and three probes, but with two blowers and four probes the Stoker is fairly unresponsive. I'll probably need to work on a telnet-based interface instead of polling the webserver, in the mean time maybe just adding some (adaptive?) delay between polls will help...

One thing I like about the Stoker is that they have arbitrary configurations. This necessitates some sort of identifier in the plug, though, so that would kill the idea of reusing Guru probes. I suppose there's no problem with putting the identifier into the female side of the plug (essentially making the blower/probes position dependent), but it would be nice to be able to auto-detect if it's a blower or a temperature sensor.

An alternative solution is to have standalone adapters that add a small identification mechanism. That also opens us up to allowing other temperature probes more easily, something like a Maverick probe adapter for example. We can also use a different connector type if we want a higher density of ports. With a little forethought we may be able to handle un-identified probes as well using a manual assignment.

Sadly, I'm much better at coming up with requirements than actual implementation Still, if you want the structure of a formal design doc I'd be happy to lend a hand.

[Syzygies]

I'll play, I like wiring little electronics projects though I'm an amateur. I thought up a circuit on my own to charge 12 V worth of rechargeable batteries using a 12.25 V iPod charger, evading the usual 1.5 V overhead by using a "current mirror". (Instead of wasting voltage I'm wasting current a different way, but that makes the charger viable.) Now I notice there's not quite the ideal board that reads both 4-pin PWM fan headers on a computer motherboard, buffers and converts to analog, amplifies to run many, many 3-pin fans under motherboard control. Easy, a pair of C-R buffers to smooth PWM to voltage, op-amps to replicate the voltages with no load, and then a pair of power amps. (I'm stuck on which one to choose for 30 watts output @ 12 volts, but I'll figure it out.) Most computer fan controls are ridiculously overwrought, but why do anything in hardware that can be done in software? My motherboard has the best idea of relevant temperatures, and it offers fine control of both PWM fan headers.

This puts me squarely in the analog camp, but I'd love to play with these digital controller boards. My bias is toward finding the simplest answer. I learned this from my Dad who designed the filter used in most digital cameras.

I'd say it's crucial that any device put up a web page; if an $85 laser printer (until 4/11 various sources, including wireless, ethernet and auto duplex) or a $30 router can manage this, so can we. Then simply identify the different plugs using the web page, never waste hardware on something that can be done in software?

[Drunk_J]

While I do like the arangement Stoker has implemented whereas you can use any jack to plug in any device, that throws in many more complications. After doing some googling, that chip (called a 1-Wire) in the Stoker is not just identifying the device, it is transmitting the signal (if it is a temp probe). So if they are using a TC, then is it must have the ability to amplify too. Same people that make the Stoker's board, also make the 1-wire chip. I have read some posts about people interfacing 1-wire chips with Arduino......will look and see what is involved.
http://www.maxim-ic.com/products/1-wire/
I forgot to look the last time the stoker was apart, but I am guessing the for fan and signal from 1-Wire chips is handled via different prongs on the phone plug (they can even have mechanical switching available on the jack side).

Oh yeah Syz, the PWM is easily handled on the Arduino. One of my first projects was creating a dimming LED via PWM. For the fan, just use a solid state relay on an output pin and control away. Also the web server is there. When you add the Wifi card, you can add the webserver software. There is already a library written for it....in my original post, check out the link to Arduino, then library section.

-=J

[Drunk_J]

Heck, apparently there is already a library and tutorials for the 1-wire.
http://www.arduino.cc/playground/Learning/OneWire
Here is an interface.
http://www.phanderson.com/stamp/onewire.html

-=J

[Syzygies]

What people do in audio DIY forums, once they get the design down, is to make a limited run of the custom circuit board. One buys the custom board from the forum collective, then goes to Mouser, DigiKey etc to buy the parts to populate it. Keep the surface mount components on a large enough scale, and one can (with care) solder them by hand.

For discrete components I've engraved blank copper boards by hand; seemed easier than the whole chemical etch thing. One still has to drill holes, though one can just pay to have the prototype fabricated. Or there's the whole SchmartBoard approach; I've found their jumper cables incredibly handy for quick electronics mods.

[jdbower]

I do have contacts in the manufacturing realm, I'd be happy to tap those for a quote once we get a design down. Depending on how many people are interested we can also look into an injection-molded case, but I'm guessing it would be a lot more cost effective to attack a generic box with a Dremel.

[Drunk_J]

A reflow oven (plenty of homemade designs out there) would be nice for SMD components, but I have hand soldered some pretty small SMD parts. There are some other homemade devices, one made of a desoldering iron, that can make the job easier. My favorite is the Reflow skillet (http://www.sparkfun.com/tutorials/59). Also, there are plenty of places online you can get the boards nicely manufactured once you have a layout drawing.
http://batchpcb.com/index.php/AboutUs

In agreement about Mouser, Digikey and have also used PartsExpress (more audio related stuff).

I definately like the idea of the custom case. FYI, the link below looks just like the Guru Procom remote case? Here are a couple of places that have loads of premades and do custom.
http://www.pactecenclosures.com/product ... classid=27
http://www.polycase.com/

An LCD readout is also a must. I did find an article on connecting an LCD via the 1-Wire system. Also found out they have 1-Wire buttons and loads of other devices that could be cool addons.

But first things first, microcontroller platform? Existing premade or completely custom? Addon board? 1-Wire system or the TC-4 shield board listed above? The biggest unanswered question is software design and computer interface? Guessing that depends some on the microcontroller.

I am already partial to the Arduino and there is so much out there for it already. They are a whole $30, so anyone can grab one and develop from that base. I have already purchased a TC-4 with lcd/button board, but willing to chalk it to learning if we can actually come up with a better way to interface whatever temp device with the microcontroller. One downside to the Arduino is nobody is currently making a clone (that I have found) that has Wifi built into the base board. There was one company, but they went out of business in the last month. The Wifi cards add another shield layer to the board and considerable expense being they are only B & G ($50-$90 which is rediculous for that). Each additional shield layer complicates the case design too. If we stuck with only one additional shield, the case I posted in the first post was already custom made for the arduino board, one shield, button cutouts and an LCD. I am probably up to the challenge with handling the board soldering for those who need it (provided the numbers were not rediculous), but I am just starting out on the software side. Would need someone to take the lead on that aspect.

-=J