BRADLEY SMOKER | "Taste the Great Outdoors"

Consumables and Accessories => Accessories => Topic started by: mhoy on April 21, 2011, 11:07:53 pm

Title: DIY Digital Controller
Post by: mhoy on April 21, 2011, 11:07:53 pm
Still a work in progress since it currently uses a simple on off (and I have to figure out how to program the buttons still). So for now, it's a compile time temperature setting.  :o  Lucky the box is easy to open. I expect to add in a PID program in the near future.

There is a master on/off, input power plug, an output heater control, one K-thermocouple input, 4 buttons, Cyrdom D1210, 2x16 LCD screen and a very simple program loaded on the Arduino UNO. There is a TC4 thermocouple/controller shield and an LCD controller.

It's all housed in a large 6"x8"x3" Radio Shack box mounted internally on some 1/4" plywood.

Here are the internals before the wiring was all finished
(https://lh4.googleusercontent.com/_0-aEomHvbkE/TbDyxr9ZcBI/AAAAAAAAAnA/3v4MnA7A2u4/s800/P1020826.JPG)

Back of the top with buttons and LCD controller before being wired up.
(https://lh5.googleusercontent.com/_0-aEomHvbkE/TbEanXAKzDI/AAAAAAAAAns/e4py-S5pCuo/s800/P1020829.JPG)

Working system:
(https://lh4.googleusercontent.com/_0-aEomHvbkE/TbDycAizcOI/AAAAAAAAAm0/pDCFuhmF99g/s800/P1020830.JPG)


Mark
Title: Re: DIY Digital Controller
Post by: squirtthecat on April 22, 2011, 04:40:36 am

Nice job so far!
Title: Re: DIY Digital Controller
Post by: beefmann on April 22, 2011, 06:44:46 am
looking good
Title: Re: DIY Digital Controller
Post by: muebe on April 22, 2011, 06:52:06 am
Nice! What are the costs for the parts?
Title: Re: DIY Digital Controller
Post by: mhoy on April 22, 2011, 09:33:52 am
It's cheaper to buy a pre-built system. :-)  However there are 4 thermocouple inputs and numerous additions that are a piece of cake for an Arduino based system. (Bluetooth Remote control interface with serial logging comes to mind).  The main designers of this card are building it for control of coffee roasters (another hobby of mine).  Coffee roasting is a fairly complex job and the beans eventually generate heat in an exothermic reaction...so I figured I'd control my smoker first. (Btw: This would also make for an excellent Sous Vide controller).

Here is a guestimate of the parts:
 $30  Arduino Uno
 $16 TC4 board with surface mounts pre-installed, $6 for a bare board, $45 assembled
 $15 LCD Adapter board with surface mounts pre-installed, $6 for a bare board
 $13 2x16  LCD 5v
 $15 Crydom D1210 (new from eBay)
 $20 misc electrical components if you didn't get a pre-assembled board
 $20 Misc: box, on/off switch, thermocouple mounts, terminal block, wire, crimp connectors, PC power cord cut in 1/2
   $4 5v-9v DC voltage wall transformer (old cell phone charger from the junk bin, mine was sitting in a box)
------
$133

TC4 Shield code
http://code.google.com/p/tc4-shield/

If you are interested in the TC4 and LCD control board see:
http://www.mlgp-llc.com/arduino/public/arduino-pcb.html

Mark
Title: Re: DIY Digital Controller
Post by: devo on April 22, 2011, 09:46:05 am
Wow way over my head.
Title: Re: DIY Digital Controller
Post by: Keymaster on April 22, 2011, 10:02:49 am
Very impressive, thanks for sharing :)
Title: Re: DIY Digital Controller
Post by: OU812 on April 22, 2011, 10:04:12 am
My head hurts now.  ;D
Title: Re: DIY Digital Controller
Post by: mhoy on April 22, 2011, 10:08:55 am
It's probably easier than you realize. It's almost entirely plug and play with a bit of programming.  At this point I'm only turning the element on/off if the temp is under/over the desired temperature.  It gets interesting if/when I add in a PID program loop.  I'm curious how close a simple on/off can keep the temp in the smoker.

Time for the good part, I'm going to brine up some more salmon so that I can get the testing started!!!!

Mark
Title: Re: DIY Digital Controller
Post by: squirtthecat on April 22, 2011, 10:15:30 am

That's awesome.   Thanks for the code links.
Title: Re: DIY Digital Controller
Post by: mhoy on April 23, 2011, 02:30:07 pm
ARGH, I'm pretty sure the main heating element burnt out 80% of the way through my smoked salmon!  Even reverting to the built in circuit yields no heat from the back element. Turning on the oven for the 175 part of the cooking...

Mark
Title: Re: DIY Digital Controller
Post by: mhoy on May 07, 2011, 07:56:27 am
Bradley shipped a new element and a bottom plastic cover and it took only a phone call. Very good service. I picked up a spare element while I was at it and they shipped with the replacement parts for free. I was only down for the week. Time to get cooking again, smoked chicken anyone?

Mark
Title: Re: DIY Digital Controller
Post by: NePaSmoKer on May 07, 2011, 09:31:22 am
Nice job on your controller


But way over my head

SO

(http://i868.photobucket.com/albums/ab242/nepas1/2300-8083.jpg)
Title: Re: DIY Digital Controller
Post by: Michaels Place on June 04, 2011, 03:29:33 pm
Nice piece of engineering work!  Have you considered selling the design to Bradley? What I don't understand is why Bradley would not build better controller technology into their own product?  Obviously they make a great product but I am just now getting very clear that the temperature swings make it difficult to produce certain foods, such as sausage or fish, without augmenting or overriding their built-in digital controller.  Anyone know if they have any plans to address this issue?
Title: Re: DIY Digital Controller
Post by: mhoy on June 04, 2011, 04:27:28 pm
Thanks for the complement, but this is an elementary controller, I've not even turned PID on yet.  :) It will only get interesting when remote BlueTooth control gets added so that I can watch the BBQ from inside on my cellphone or computer and adjust it while watching TV.  ;D  Although if I do this, it makes it hard to convince anyone that I'm slaving over the hot coals making a delicious bbq for supper.  ;D

Bradley has a digital version which I'm assuming has much better temperature control. Remember that it all costs money to implement and get appropriate certifications. The OBS seems to have CSA. I know that some tools don't even get brought into the country from Europe without UL and many nifty things just don't get here.

Mark
Title: Re: DIY Digital Controller
Post by: jsmanson on September 21, 2011, 07:24:40 am
Interesting project - I just purchased some Auber parts for a "do-it-yourself" system, and I was thinking about putting together a Picaxe processor and display/keypad as you have done.  I am going to ask the folks at Auber if there is a way to communicate with their PID devices, if so, the processor could tell the PID what temp to maintain, and the PID could do the heater cycling.  I bought one PID to maintain heater cabinet temp, and another one to monitor meat temp, so I'd need to be able to communicate with both PID's.  I'll let you know what I find out....

John
Title: DIY Digital Controller
Post by: mikecorn.1 on September 21, 2011, 08:31:20 am
:rolleyes:


---
- Sent from my iPhone using Tapatalk
Title: Re: DIY Digital Controller
Post by: Tenpoint5 on September 21, 2011, 09:39:13 am
Yep it is fact that this whole thread has me LBS!!! (Lost Bigger than 0e)
Title: Re: DIY Digital Controller
Post by: mhoy on September 21, 2011, 10:09:35 am
John: I'm very sure I don't understand how you would control two PIDs instead of one.   Why not implement your controls with dual temp probes and control a solid state relay with the picaxe itself?  There is PLENTY of time to compute as the smoker doesn't change temperature all that fast even when full heat is applied (or removed). Once you have this working, add a second temperature probe and you can add smarter software to switch from cabinet temp to meat temp as you go.  Get this working and sell the PIDs (or get a second smoker).

Mark
Title: Re: DIY Digital Controller
Post by: muebe on September 21, 2011, 10:15:08 am
mhoy how did your arduino setup finally turn out?

Got any pics of the finished product and details?

There is a guy on another forum who is using a arduino to run his traeger and has a really cool setup. Thanks for posting!
Title: Re: DIY Digital Controller
Post by: mhoy on September 21, 2011, 10:21:27 am
The final setup looks identical to the pix I've posted. Setup has the lid on the box and I've used it a number of times. Makes things pretty darn easy. Been too busy this summer to do much smoking. Time to get back to it.  :-*

Changes I would make:
-removable plug for the thermocouple and hard wire it inside the box.
-figure out how to determine the thermocouple is not present.....(it was forgotten onetime....)
-fix the bug at the 7 to 8 hour mark where it reset to the default (ARGH at least I noticed).
-write a better key board decoder code, it scans the keyboard too slowly (perhaps lock out the temp reading calcs and PID loop while doing keyboard, not sure). The a/d decode isn't all that swift on this setup, but certainly sufficient.

Mark
Title: Re: DIY Digital Controller
Post by: muebe on September 21, 2011, 10:27:12 am
Very nice setup. Thanks for sharing ;D
Title: Re: DIY Digital Controller
Post by: squirtthecat on September 21, 2011, 10:35:32 am

Mad Scientist Smokers!    I love it..
Title: Re: DIY Digital Controller
Post by: OU812 on September 21, 2011, 11:57:05 am
Yep it is fact that this whole thread has me LBS!!! (Lost Bigger than 0e)

What Chris said.  ::)
Title: Re: DIY Digital Controller
Post by: jsmanson on September 21, 2011, 10:11:32 pm
Hi Mark, so I take it that you are doing fine with your project without the PID wired in?  You're just turning the heater on/off either side of the desired temp?  It sounds like the pid's are doing some kind of fancy algorithm stuff, but maybe we can get away without them as you suggest.  Hooking two temp probes should be fine, the meat probe would just be the trigger to turn off the heat or go into a standby mode...  I'll do more research on this, and keep you posted!
Title: Re: DIY Digital Controller
Post by: mhoy on September 22, 2011, 07:13:37 am
jsmanson: Correct. Figured I try something simple first and simple was good enough for me (which in this thread is kind of relative I guess). I suspect that adding a PID loop to the code wouldn't be too hard as there is an Arduino library for it. However tuning it and testing a PID does take some time. It worked well enough for some rather tasty pork ribs last night that my wife smoked.  8)   Having an auto-standby mode seems useful... (I have extra thermocouple channels.....)

Give yourself enough room in the box you pick to be able to lay things out nicely. Makes it easier to work on and easier to fix should you need to. Be respectful of the AC circuit since it can fry the electronics if hooked up wrong (and potentially hurt you too).

Mark
Title: Re: DIY Digital Controller
Post by: jsmanson on September 22, 2011, 10:21:42 am
Mark, I found this comment on the picaxe forums in the UK, from a guy who was building a PID to control coffee roasting..

This fellow was suggesting, as you have, that a full PID is probably too fancy for the coffee roasting application, similar to our aplication....

"Rather than a PID try using a simple circuit that switches an output on or off as a pulse where the pulse length is proportional to the error between the measured temperature and the set point. Sample the error at period Tp(sec/min) and make the maximum pulse for the maximum error as Tp. ( sec/min). This type of contoller approximates a PID loop but is easier to implement for on/off controls."

Link:  http://www.picaxeforum.co.uk/showthread.php?9027-1st-attempt-at-PID-controller&highlight=max6675


What do you think of that??  I like the simplicty of the approach, and wouldn't need the calibration and learning steps that the full PID needs.  I have found code snippets for writing a full PID implementation, but I thought at least I'd try this simpler approach first.  I also assume that the pulsed heater logic would only come into play when temps got within a defined zone of the set temp, as one wants to get the temps up as quickly as possible.  I can see, though that the one thing this approach would guarantee is that the temps would cycle around the set point as the error would go to zero when the set point is reached, so temps would have to drop before the heater would turn back on - and the PID from what I gather, if properly tuned, would allow the temps to stay right on the set point with the PID figuring out the correct proportion of cycle time to maintain the temp at the set point.

Also Mark, looks like I will need a couple of Max6675 thermocouple amplifiers to provide for the interface to the picaxe, which will read the data through the SPI port on the processor.  Shouldn't be a problem other than having to solder those little soip chips lol!  The Max6675's are about $20 on digikey, so it will be $40 for the interface for two temp sensers.  It looks like I can use the one SPI port to read multiple devices, so I will connect both probes through the SPI, each using a separate Max6675.

I'm going to slide in an eeprom so I can store a range of cooking 'menus', which can be selected by the user on the keyboard at startup.  I think I'll also use the thing to fully control the smoke system as well, I will need to figure out how to bypass those standard digital controls, but it shouldn't be difficult.  a connection to turn on the puck advance motor on every 20 mins, and a connection to turn on the smoke heater when smoke is desired.

Title: Re: DIY Digital Controller
Post by: mhoy on September 22, 2011, 11:35:22 am
Long thread you posted to, but the quoted part seems very reasonable. Once everything is built, it's only a matter of software choices.  ::)

My controller also came from the coffee crowd (another hobby). If you could switch to I2C you could use the same board I used (and it's inexpensive) and there is an option to get the surface mount chip pre-soldered, which for my old eyes is wonderful.   ;)

Mark
Title: Re: DIY Digital Controller
Post by: jsmanson on September 22, 2011, 04:36:28 pm
Check this one out mark!

http://www.instructables.com/id/The-Smoke-O-Tron/

Title: Re: DIY Digital Controller
Post by: Joseph Haddad on April 08, 2013, 08:16:09 am
check out this PID for android
http://forum.bradleysmoker.com/index.php?topic=32080.0
Title: Re: DIY Digital Controller
Post by: KyNola on April 08, 2013, 02:36:16 pm
A 2 year old thread. :o

What type of smoker do you have if I may ask?
Title: Re: DIY Digital Controller
Post by: Joseph Haddad on April 08, 2013, 05:20:35 pm
new style OBS with dial on smoke generator
Title: Re: DIY Digital Controller
Post by: KyNola on April 09, 2013, 07:55:51 am
Cool! Thanks.