SmartBBQ: WiFi controlled 4 probe BBQ controller with blower output

I’d like to start an open source project for a smarter BBQ device for grilling or smoking. Several people have created them already, but maybe we can contribute to one project and make it awesome! What features do you want it to have?

  • 4 Maverick Probe inputs
  • 4 probe indicators(LEDs)
  • PWM smoker control
  • 3-4 digit 7 segment display or touch screen?
  • 3 button input or touch screen?
  • powered by 4 AA’s or a rechargeable?
  • of course Spark Core powered
  • and of course Spark connected apps

Here is the bench top start. I’ll get code and schematics posted soon so we can iterate. Throw your ideas out there and let’s see what we can build!


this is great.
how would you feel about putting in 2 PWM controllers?
there are 2 reasons

  1. with this many thermistor probes, you could potentially control two independent smokers. for big bbq days, i like that option
  2. i have been obsessed with humidity control recently. i spoke with nathan mirvols (modernist cuisine) about my bbq stall issue, and he directed me to a whole lecture on the stall issue as it relates to humidity levels. if i could use the second PWM to control a misting system, we’d be in business! i would add code to the core that detected that “stall” was happening, and then just add some humidity

the best solution though would be to measure humidity and set a target. unfortunately, humidity at 200+ degrees, seems expensive to monitor. anyone seen something that works otherwise??

last, i think this solution has a great opportunity to solve the sous vide market as well. though there seem to be a lot of sous vide options out now, i dont think enough of them are open source…


to answer a few more questions…

3-4 digit 7 segment display or touch screen? – i think an OLED screen (non-touch) has its place. touch is way too expensive, and horrible in outdoor environments. i think the complimenting mobile app should be where people interact.
3 button input or touch screen? – neither! ok. maybe a few buttons with the OLED screen.
powered by 4 AA’s or a rechargeable? – ouch, a set of AA’s wont make it through a full smoke. unless the wifi is turned off most of the time. a rechargeable might work better, since people will plug the device in for very long smokes…

time to call in the elite (i just pictured putting the bat symbol into the air!)

i know @wgbartley is thinking about a smoker project, he might have interest.
@peekay123 made the OLED libraries. he might have some insight on the lib. also, we will likely need his help if we plan on porting a PID library.

@kennethlimcp expressed interest in being helpful in the last thread. though i dont know how much BBQ gets done in his part of the world :smile:

and @BDub gets a shout just because he became the thermistor king when we were first having issues with the maverick probe!

who am i missing? this feels like a comic book movie…gotta love it.

oh ya. @timb, i think we chatted about smoker tech at maker faire. don’t know if you are working on a “pro” version, but any help is always welcome.

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Asians do BBQ yo! :smiley:

Let me know how I can help!

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Yeah, I’m working on something BBQ related for a client, so I can’t help you much right now, but I will pass this thread along to them!

Is there some way you could measure the humidity coming off the ventilation? I'm sure there's a way you can correlate humidty inside versus what's coming out, but it might take several smoke sessions to get all the data. Who's hungry? :wink:

I was thinking of running the ventilation or at least a small part of it through a radiator of sorts that would cool the air back down before it interacted with the humidity sensor. Complicated, but how else are you going to get that perfectly smoked meat.

Agree, just plug in a wall wart and/or use a fairly large capacity lipo. Ideally it would use an external high gain antenna to ensure connectivity where ever your smoker is.

Is that in °C or °F? I've been searching for high-temperature hygrometers, but the best I've seen that's still affordable goes up to 250°F. It's an analog dial type, so not something that could be easily integrated with the Spark Core. However, you could use one to take your internal readings (manually) and get the cooled, exhausted air humidity to draw your correlations. The only problem with that is I'm sure each smoker would be different.

In other news, there seems to be a niche market for MCU-compatible, high-temperature hygrometers!

its F.
problem is that some people smoke at 300! the horror!

you got a link to that hygrometer?

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This one goes up to 250°F.

OK so at 300F you are firmly in thermocouple land. Not much else is going to work well in that heat.

Have you thought about a wet-bulb/dry-bulb psychrometer? At that temp. you would have to feed the wet-bulb reservoir from outside the heated area to avoid steaming off all the wet-bulb water.

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Ya, this shouldn't be a problem.

I like this option, assuming the OLED is not too expensive. A 7-segment is super cheap. Did you have a particular one/size in mind? I like the idea of 3 buttons. Select, Up and Down, for selecting a probe and then setting a temp. The apps can provide a much richer experience, but if my phone dies etc. the device becomes a spark powered brick :smile:

The Maverick thermistor probes are rated at 410F or are you talking about the hygrometer?

I have a pair of those and I don't find them to be that accurate. But you are certainly right that they are rated for 300+.

Lately I have taken to buying Taylor NSF approved digital instant thermometers on sale, the ones that have a tiny calibration trim pot and I calibrate them in an ice slurry. You can't leave them in the heat, and eventually they become non-waterproof and die, but they are very accurate. I have thought that I should take one apart for the sensor next time I kill one.

here is an OLED screen for less the $15

or a small one for less than $12.

the advantage to the 7 segment is that you can see it from far away....

anyone else have a thought on the matter?

Which Maverick probes do you happen to have? I have the ET-732 which according to this link is not as accurate as the other Maverick models they recommend. When using mine I did notice the temp jumping more than I would like. I want the best valued(price/accuracy) probe I can get, but if we can figure out the right constants for them we can set it up to use whatever people have on hand.

If it's Spark-powered, you can see it from 2,400+ miles away. I toggled my deck lights from my phone all day at Maker Faire. It'd be even easier if you made a Pebble app for it!

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Those OLED's are super cool. I'm leaning towards the 7 segment for cost, simplicity and I'm guessing a small power advantage. These can both be designed around I2C interface though, so we can do the design up to pcb without having to commit to one or the other. Curious to hear others' thoughts as well.

Can anyone recommend a good I2C controller for a 7 segment display? I’m using the HT16K33 on an Adafruit Backpack right now. It’s rated for 5V although it has worked flawless for me so far w/ the Spark on 3.3V.

totally agree on the 7 segment display in regards to pricing and simplicity.

the killer on the power will be running those fans. i have a hard time seeing this run entirely on battery. but i could be proven wrong.

so are we going back to the 7 segment display and all the serious “intelligence” being on the mobile app?

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