Computer interface to the WSM


 
I was unable to find a solution with thermocouples. However, that is the solution I wanted to use. The most significant problem for me is that I had to teach myself electronics to build the interface circuit first. (ie: I didn't know ANY electronics). I do know how to program however. If you find a cheap way to do thermocouples, I'd love to share notes with you!

-Matt

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Bob Hruska:
I've done a little more research this evening, and it appears that the NuTemp probes might indeed be just plain K type thermocouples. I will order one of the AD595 ICs and see if it works.

I am still very curious about the probes that The Stoker uses. All of the serial bus temperature sensors I can find do not go up to the 300-400 degree range. Anyone??? </div></BLOCKQUOTE>
 
Thanks Matt. I will have the AD595 to play with sometime after Memorial Day weekend. It's a $15 IC, so I am hoping it's a good cost effective solution. Of course an analog MUX will be required to use more than one thermocouple.

I'll keep you posted.
 
boy, I sure am glad that there are people in this world much smarter than I am. Bob, Matt, keep up the work. I can't wait to see what you guys come up with.

- Adam
 
Really neat project. Keep us informed. There is a company that makes microprocessor project boards, and all sorts of sensors and controllers to interface them. They have motor and servo controllers for activation of the vents, and they have thermocouples for measuring temps. Not really sure what language they use to program the microprocessors, or if it would be capable of doing what you want, but it looks like it may. Anyway have a look and tell me what you think. I would be interested in tinkering with something like this if it is a viable option. www.parallax.com
 
Have a look at this http://www.extremetech.com/article2/0,1558,1833596,00.a...TRSS02129TX1K0000532 This is pretty much a home built version of the BBQ guru. Once it is all said and done you could most likely buy the guru for cheaper. But if you want to use it for a learning experience this would probably be the way to go. They used the parallax board which would have unlimited experimental applications. The unit that was built was a stand alone unit with no logging capabilities, but there must be some way to interface it to your computer for logging purposes.
 
Dan thanks for the link. It's the first technical info I have seen for the Nu-Temp probes. I'm kinda bummed they are just thermisters...

Here is another link to a similar project:
Circuit Celler BBQ Controller

My project is going to be Atmel based (ATMega32) and I am going to try to use thermocouples. Parts are ordered, all I need now is the UPS guy to show up and some free time. I'll keep you posted.
 
Bob,
That is a great article. Being new to electronics, I didn't understand how to interface with thermocouples properly. That article made sense to me. Thermocouples are 100% the better way to go given their temperature properties. It would be nice to have accurate probes that don't get melted....
 
Matt, in my opinion the design in that article does more work with more components than is necessary to use the thermocouples. The interface can be done with one IC, the AD595. See this article for how simple it is:
Circuit Cellar Oven Controller

I plan to use that interface in conjunction with the 74HC4052 analog mux to use 4 thermocouples. I have not found a good cheap source for thermocouples with stainless probes, but have seen lots of bargains on ebay. I'll probably go that route once my proof of concept prototype is done.

I spoke with one of the Stoker guys and their probes are similar - except they use one Dallas Semiconductor chip per probe and no mux. Way simpler, but also more expensive. For $30 per probe, buying from them would be a great choice - but if you want 4 of them it adds up.
 
That is a very cool chip.

I was reading the data sheet here: http://www.analog.com/UploadedFiles/Data_Sheets/421725987AD594_5_c.pdf

Just to make sure I understand it properly, looking at the chart on page 3, it looks like it will give a swing of 0V to +5V over a temperature range of 0C to 500C. Am I reading that right? That would then require a supply voltage of at least 7 volts to drive the output up to 5V.

The A/D converter I am using takes an input of 0 to 5 volts and converts it to a number between 1 and 1024. It looks like this chip would interface with it quite nicely.

I did not find a good source for cheap thermocouples either.

-Matt
 
It's amazing how fast the bar is raising. Back when we were serious competitors a whole two years ago a Weber and an experience hand palm was all that was needed to win. Now the Guru is everywhere. Even Cookshack's Fast Eddy which is a winning machine (like the WSM) is getting all the Guru features and teams are lined up to buy it.
 
If anyone has any of these "laying" around, let me know
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Advantch ADAM 6011

I would love to get my hands on one of these (I'm not willing to shell out the ~$500 required) and tie thermocouples into my WSM!

For those tech-savvy, the protocol supported by these devices seems extensive enough that you could implement a fairly robust data collection system. The software to implement such an app shouldn't be too difficult, although one would need to understand socket programming.

Would someone like to send one to me as a Christmas gift?
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I am not quite sure why this has never been brought up, but my WSM has no problem holding temperatures of 300 degrees with just draft air. I am just wondering why the positve pressure of a fan is needed. I had an idea, just didn't have the time or materials to implement it. Basically make an adapter for the WSM going into 2 inch pipe. Put a butterfly valve in the center of the pipe and use a servo for activation of the valve. Doing things this way would more closely mock the numerous vent adjustments needed to be made.
 
Dan, the point of the fan is that it is the ONLY source of air. You close all the other bottom vents and use the fan to regulate all the airflow. It isn't used to "increase" airflow per se. It's a lot simpler way to make big swings in airflow without having to put some sort of motor on every vent. You turn it on when the temp drops too low, and you turn it off when the temp gets too high (well, you can get a lot more complicated than that - but that's the jist of it) Make sense?
 
An update is in order...

I have prototyped using a single thermocouple probe. Right now it just monitors the temperature and logs it to the serial port and LCD. I am planning on logging my next cook just to see how things go.

Two next steps: Add a mux so it can use up to 4 thermocouples, and add a blower with control software. I'm not sure if I want to go cheap and try to use a little muffin fan with a homebuilt damper, or just go ahead and buy a guru fan. That's still up in the air.

Here's a pic - pardon the mess:

 
Bob, that looks promising. Are you data logging the temps through the serial port to your computer?
 
Yes, I have a data stream going out the serial port on the microcontroller.

I just got two thermocouples with SS probes off of e-bay for only $24 so I am getting the mux all set up to monitor multiple temps. As is evident in another thread here somewhere, I'm about done researching blowers and will pull the trigger on that soon as well. It's all coming together, but I don't have as much spare time to do it as I would like!
 
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