Version 2 of my homebrew controller


 
Originally posted by Ed Pinnell:
Ok, got it, thanks Bryan! Changed the other bug, too. MUCH better now.

I made a blower mount for the kettle out of an old aluminum pot yesterday and sealed the rotisserie ring to the lower half. It's sealed up tighter than a sea turtle's bottom now...I made the max auto fan speed variable available remotely in case I need to play with it.

The spare ribs are going on in about an hour!
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Oh **** you and your endless BBQ. Can you design me some sort of robot arm that can take a piece of meat out of my fridge, put it on the egg, and fire it up? Bonus points if there's a web interface for letting me select if I'd like ribs or brisket or butt.

Glad the bug fix worked. I couldn't test it at the time considering all my devices had ambient sensors but as soon as you mentioned what was going on I could see what was happening. I'd put out a new version but I've got things sort of torn apart with the alarm code going in. I'm back up to 29,458bytes and I don't really like how well it works on level of annoyance turning alarms on. I need to swing by a dollar store on the way home from work today too, to find something to steal a piezeo speaker out of and see if it actually works too.
 
Originally posted by Ed Pinnell:
Need to make the PID available externally without re-compiling.
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Yeah after looking at the serial protocol, I was thinking "why the heck does it need to be so complicated?". I think I'll just make it spit out the CSV every time it takes a measurement prefixed with something recognizable.

The setters will just take the same form as the web URLs so to set a pid I you'd send over serial:
/set?pidi=x.x
 
Originally posted by Ed Pinnell:
2011-01-25 14:05:14 +00:00, 225,223.7,0.0,0.0,78.6,54,100,38,0
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Yeah I was just going to take the CSV the web server sends and reuse the same code to send it serial. Where does the time come from? Does the router add it?

Also, I've had problems trying to lower the temperature too much too. What seems to happen is that while HeaterMeter is waiting for the temperature to drop, with the Egg sealed up tighter than a drum, the fire gets pretty much snuffed out. Once this happens you almost need to manually go poke the coals around a bit and maybe even hit them with a blowtorch for 10-20 seconds.

I can currently control my HeaterMeter remotely using the WiShield and a hole poked in my firewall. The issue I have is that ribs take 5-7 hours and I like them wrapped up in foil for 1-2h of that. I am gone 11 hours from the time I go to work to when I get home (which makes me cringe a bit now that I see that) so that's too long for ribs. 11 hours isn't enough for a butt. Well... maybe... and it is on sale this week... golly maybe I will try that tomorrow.
 
Originally posted by Ed Pinnell:


There is a period of about 40 minutes going from 225F to 150F where the blower did not run at all. I think this might have killed the fire pit. A servo to open and close the upper vent to exhaust the heat while giving the pit a shot of air with the blower to keep the fire going might help.
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What about steal from the Traeger program. They have a background "smoke" routine that keeps their fire alive by dumping in some pellets every X time regardless of temp. What about a ?30? second fan burst every X seconds if the fan is not running. I bet with some some tweeking of the delay and fan %, you wouldn't have to open the vent, just give it a little 'fan' on a regular basis. It wouldn't drop as fast but it wouldn't O2 starve either.
 
Maybe that even is over complicated. Looking at your graph I see very few time slices where you fan was below 20%. What would happen if you set the fan to always run at X% minimum. It might hurt your overshoot recovery times slightly but it might take a bit less code. And you only have one variable to tweak.
 
Originally posted by Ed Pinnell:
David, I want to do the wireless meat probe next but RF Link Receiver that the DCDW project uses is no longer available through SparkFun. Do you have any other ideas?
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What is your budget? I helped with a project to wirelessly measure the G forces on a connecting rod while it was running in an engine. I think I can still source some of those parts. However, they were not cheap even for a fortune 50 companies budget. Similar heat tolerances to your needs but I'm guessing your rotisserie isn't pulling 400G's. :-)

EDIT*** You got me thinking about that project again. Withstanding the G's was a big part but 'normal' solder starts to melt in the 300 to 400 degree range. Unless you are going to be VERY careful with your temps or build something very very custom, long term exposure to that kind of heat is going to be an issue with any kind of off the shelf build.

I'll keep an eye out. I still haven't given up on intercepting(easy part) and decoding(unknown so far) the Maverick's wireless signal via PC or Arduino.
 
I have a silly question - does anyone know if there is a difference between the smoker probes and the food probes? I accidentally ordered two food probes... it doesn't appear that there is a difference in the temperature output, but I wasn't sure if there was some reason I shouldn't just go ahead and use a food probe as one of my smoker probes.
 
Originally posted by JD Siegrist:
I have a silly question - does anyone know if there is a difference between the smoker probes and the food probes? I accidentally ordered two food probes... it doesn't appear that there is a difference in the temperature output, but I wasn't sure if there was some reason I shouldn't just go ahead and use a food probe as one of my smoker probes.
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I'll agree with Ed and say they're identical except in the physical dimensions of the probe itself. The food probes are 5" or 6" long and have a 90 degree bend at the end, and the smoker probe is 3" or 4" long and straight with a blunt tip. I've also picked up some of the "high temperature" probes which have longer cords and won't melt when exposed to heat over 400F (like the ET-73 probes did). They seem to be drop-in replacement parts, and I'm using one right now as my pit probe.

butt-20110127.png

I'm running HeaterMeter today from work using the serial to linux and some shell scripting magic, like it would be in the router-based configuration. Excuse how ugly this is right now but here is the script if you want to have a look at it while it is WIP. Basically it reads the serial data, stores it in the RRD, then outputs a static json file for the web page. This static json can be done on the router too, just writing the file into the /tmp ramdrive every second.

The RRD graphs are pretty uninteresting. I thought the 60 second one would be pretty neat to see how the temperature cycles up and down but 60 seconds isn't enough to make a cycle.
http://home.capnbry.net:22674/~bmayland/rrd.html

Ed do you do anything to protect your food probes when cooking? Mine seem to really heat up fast. Like I put a 35F, 5+lb butt on the grill and 2 hours later the food probe says it is 90F. Wrapping some aluminum foil around it seems to make it track a lot better, but today I can't try that out because I'm a 40 minute drive away.

For some reason, my fan runs a lot less then Ed's. I have a lot of fuel in there, probably 4lbs (I was sleepy this morning and didn't bother to weigh it), so maybe that makes a difference.
 
The best part about being too far away to do anything about it is that I get to see what happens when things go nuts. Like at 12:25pm suddenly the grill decides "hey, let's just rise in temperature by 15 degrees without the fan even running". Makes me wonder if the blower fell off the egg again, considering I still haven't made myself a nice metal blower mount yet.

EDIT: Speaking of which I realized I never posted photos of the fan mount I made for my Dad's device. I used your design which was much less complicated and just as functional as my original plans. I'm not proud of it, but I am pleased with it.
fanmetal-1.jpg

fanmetal-2.jpg
 
Originally posted by Bryan Mayland:
Excuse how ugly this is right now but here is the script if you want to have a look at it while it is WIP. Basically it reads the serial data, stores it in the RRD, then outputs a static json file for the web page. This static json can be done on the router too, just writing the file into the /tmp ramdrive every second.
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Awesome stuff Bryan! Very consistent grill temp! Love it. Thanks once again for sharing.
 
Here you go Bryan:
http://vtfood.com/bbq/heatermeter.php

Doesn't work in IE. Not sure about Chrome or Opera, but it works great in Firefox.

It doesn't need to be PHP. Just create a page like this to launch another, and put this code in the <head> section:

<script>
<!--
window.open("http://home.capnbry.net:22674/~bmayland/bbq/","fs","fullscreen=yes, resizable=yes, status=no, width=500, height=340")
//-->
</script>
 
Originally posted by Ed Pinnell:
I've been watching that same thing...I'm nervous and I'm 'way over on the other side of the continent!

In my cook in December I had the pit probe at grill level clipped to the rack and it slipped off and was touching the roast. I couldn't figure out why I couldn't raise the grill temp while I could raise the dome temp with the set point. Maybe there should be some logic between the two...
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I previously had a webcam on my wireless thermometer so I could monitor grill and food temps using my phone. I was at a parade with my family and the grill started to take off for some odd reason. I called my helpful neighbor and walked them through the process of closing the vents. Crisis averted!
 
Originally posted by Ed Pinnell:
I think we need a webcam, Bryan!
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Haha that's what my boss said too. But if I could see if something was wrong then what would I do about it? I guess then I would know if I should pick up a pizza on the way home because the BBQ went haywire.

The hardest part of making BBQ now though is the worrying; I spent, what, 10 minutes cleaning the grill, loading it with charcoal and hickory, and putting the butt in a brine. 10 more minutes this morning to put on the rub, fire up the grill, set the HeaterMeter setpoint.

About the RRD: the idea is that it would run on the router and be stored in /tmp then maybe committed to storage every hour. The CSV log file is generated by the script as well. That might be able to be written to the SD card / USB drive directly. Today's cook is still going to a full PC Linux box through a pair of XBee serial connectors. I've been too busy in the HeaterMeter software to have done anything in DD-WRT other than mount a USB stick and install some ipkgs.
 
I didn't cut two at once because I was more worried about messing up so much that I ran out out metal. My first attempt at the folded bit looked like I cut it without measuring twice or even once.

I don't know what happened with the big spike there, but it is odd that the temperature at the grill went low by the same amount the dome went high. Like you said, my egg doesn't seal as well as yours does so I'm wondering if it somehow managed to catch a draft. The winds here are calm so I think I can rule that out. I had to sit on my hands though to not put the fan into manual mode to run for a few seconds when it hadn't turned on for 30 minutes. I was worried the fire would be out by the time control resumed.
 
Everything seems to have settled out. Where I'd really be interested in having a webcam is inside the pit itself so I can somehow relate the temperature curves with some event that is occurring in the firebox and maybe arrange things in such a way that thing are a little more even. I just dump whatever lump I'm going to us into the egg and level it out, and arrange wood chunks 5-6 wood chunks in a circle and light the middle with a blowtorch.

I am hoping to eat about 6:30-7pm. I get home about 5:45-6 and wanted to give the butt some time in aluminum foil. The plan was that if it was going to be done too early that I'd drop the temperature to 200F and let it sit there. Even after I pull the meat I'll drop the temperature and see if it holds, just for science sake.

I bought a pretty big sheet of metal to make my fan mount but I think you underestimate my confidence in being able to not mess things up! Should be pretty easy for the second one now that I have a better idea how to use the tools. I am thinking about adding a little flap-down door on the end of the blower mount too, thinking that my egg sucks in outside air through the blower when it is off.

I do love me some rotisserie too. That's not something I'm ready to invest in. I do wish I had friends who were more into outdoor cooking so I could convince them that they need to get one... and I can eat there.
 
Originally posted by Bryan Mayland:
Where I'd really be interested in having a webcam is inside the pit itself so I can somehow relate the temperature curves with some event that is occurring in the firebox and maybe arrange things in such a way that thing are a little more even.
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You can do a webcam in the firepit. I've seen these in use in smelting applications, they are cool. You will not like the price though.

http://www.jmcanty.com/Items.aspx?catId=109
 
Originally posted by RJ Riememsnider:
I think he means Round Robin Database.
Like RRDTool, etc.
http://www.mrtg.org/rrdtool/
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Oh yes. Thanks for clearing that up RJ, I misread Ed's original question. That's what I get for trying to squeeze my web browsing into the amount of time it takes for my project build to complete.

And David, those are pretty cool. Just a small amount of overkill there unless I want to show my guests what it looks like while their steaks are getting seared... at 2500F.
 
Originally posted by Bryan Mayland:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by RJ Riememsnider:
I think he means Round Robin Database.
Like RRDTool, etc.
http://www.mrtg.org/rrdtool/
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Oh yes. Thanks for clearing that up RJ, I misread Ed's original question. That's what I get for trying to squeeze my web browsing into the amount of time it takes for my project build to complete.

And David, those are pretty cool. Just a small amount of overkill there unless I want to show my guests what it looks like while their steaks are getting seared... at 2500F. </div></BLOCKQUOTE>


No problem! I loved my Amiga. Alas we parted ways sometime in the 90s but I still fire up my Amiga emulator from time to time and reminisce.
 
Originally posted by Bryan Mayland

And David, those are pretty cool. Just a small amount of overkill there unless I want to show my guests what it looks like while their steaks are getting seared... at 2500F.
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I was really thinking about how cool this would be a while back and did spend some serious time looking for a mid temp camera. It seems there is not much between normal and extreme temps. This is as close as I found.
http://www.firevideo.net/
I don't think they are meant for the constant heat soak of a long smoke, although on one of their spec's I saw that it said withstands heat up to 900 degrees. That has to be just a flash of 900 degrees, not actually getting the whole camera to 900. They all seem to be a record and watch later setup which isn't really what we want. But it could be at least a start if you wanted to talk with them about parts sourcing or other ideas.


Back on topic I got my wrt54GL back from the dead with a Jtag cable last night so I think I'm going to head down that direction.
 
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