Arduino

Is anyone else (who reads this) playing with Arduino? It’s a kind of open source electronics kit.

I’ve just ordered the StartFun Inventor’s Kit to get me going, which is a heap of varied components together with an Arduino Uno controller – an easily programmable microcontroller. It looks a lot of fun, and it is possible to build quite a bit of stuff with a minimum of soldering, which suits me. It means I can play away developing my prototype, then call in a friend with a steadier hand when I have something worth building.

My ultimate aim is to build an automatic temperature controller for my pellet grill. When I bought it, my grill came with a manual 3 way controller – Smoke, Medium and High. All that does is control the feed of fuel by time, not temperature. It works, but it isn’t as flexible or as accurate as I’d like.

In the States, these grills come with an option of digital temperature controls, which – due to the different voltage – is not available over here.

Then I found a supplier who were re-engineering the digital controls for 220-240V, so I ordered one. Unfortunately, when it arrived, I found that the controls they were re-engineering were old (for the US) stock – a model generally accepted to have poor logic. Furthermore, it didn’t actually fit my grill (not without a hacksaw), so I sent it back for a refund, and found myself back at square one.

On one of the forums I read, there are some guys playing with PID controllers, with some success. But then I came across the Arduino, and the wealth of add-ons available. There are already some people using it for BBQ control, although not the same kind of grilll as mine; they are controlling airflow (and thus temperature) with a simple low-voltage fan, whereas I need to control the pellet feed mechanism, which means controlling a 240V relay. Should be possible, though.

For the moment, I have just purchased the Inventor’s kit, to have a play – I can simulate my grill with a couple of LEDs, and see if I can get the right logic working. Then I can start buying the additional components I need – the relays and a WiFi add-on.

I will probably spend as much as I was going to on the digital controller, and possibly more than the guys using PIDs. But what I hope to end up with is something that is remotely monitored and controlled over WiFi, so it can be cooking downstairs, while I am working upstairs. Because the interface is going to be web-based, I should be able to access the controls from my desktop or even from my Android phone!

But that is a long way off, I think. I’m just going to play for a while.

19 Comments

  1. May 11, 2011

    You bastard! *g* WantWantWant! And more sensors and other ‘stuff’ than even I have thought of…

    • chris
      May 11, 2011

      One of the other kits available is the Electronic Brick Kit:

      http://www.coolcomponents.co.uk/catalog/product_info.php?products_id=513

      Also Arduino, but you have a shield (read daughterboard) with lots of sockets on it, and each component is on a separate little module of its own.

      Very easy to use, and definitely no solder required. I decided to go more for a more conventional kit, but I do intend to utilise the brick relays, as it means I can mount the relays separately on leads – this both lets me position them conveniently for their connections, and keeps the 240V safely away from the arduino.

      • chris
        May 11, 2011

        Note that unlike the first kit I linked to, the Electric Brick Kit doesn’t actually include the Arduino itself, hence the cheaper price.

      • May 12, 2011

        Oh dear *g*. Too tempting. Is there an opto-osolator addon to control the relays? I prefer to do anything using mains near low voltage via optos, preferably socketed so that when (not if) something happens I only have to change one chip.

        Did you see the robotics section? A ‘wheel’ with loads of odd cone-shaped ‘wheels’ so that it can spin on the spot or go sideways as easily as forward and back. And in the sensors a board with 9 movement sensors (accelerometers in all three axes, magnetometer, etc.).

        No time…

      • chris
        May 12, 2011

        Some of the relays available are opto-isolated, some aren’t. Most of the ready to roll modules are mechanical, which is a shame. However, empty brick module circuit boards are also available, so it wouldn’t be that difficult – even for me – to make a SSR brick with exactly the component I need. Or two or three, and have one as a spare.

  2. I first encountered Arduino last year via my favourite on-line knitting magazine, Knitty, which was offering a kit to build a bag with a circuit and LEDs to keep track of (very basic) knitting patterns.

  3. May 11, 2011

    My first thought was “why on earth do you want wi-fi on a BBQ”, but yes that would be cool. (If the problem with the US controls is really just the voltage, a 240V-110V transformer would be a lot simpler, but not as fun to play with. Changing 50Hz to 60Hz would be trickier (or at least more expensive) though.)

    • chris
      May 11, 2011

      Alas, a step down transformer won’t work without a complete rebuild. As well as the 240V manual controller, there is also a draught fan, auger pellet feed and hot rod, all of which are 240V, and take their feed from the controller.

      So replacing the manual controller with a 110V controller is a no-no, even with a transformer, as it will mean the other components aren’t getting the voltage they need.

      What this means is that I either have to build my own controller (or make do with what I have), or replace all the components. A complete set of components will be 220 dollars, and the cost of the Arduino kit won’t be far off that, and more fun.

      With regard to going WiFi, the standard remote grill thermometers (which are increasingly popular) tend to be pretty shoddy on their range. I recently moved my grill down the garden, and can’t get a signal in my lounge now. Moving from a proprietary wireless solution to simple WiFi means any range issues can be trivially addressed. Ultimately I would have multiple temperature probes attached to the Arduino – one for the grill temperature itself, and one or more for the food. In particular, when cooking low and slow, it is important to maintain the temperature, and not let it go too high, or go out.

      • chris
        May 11, 2011

        “As well as the 240V manual controller, there is also a draught fan, auger pellet feed and hot rod, all of which are 240V, and take their feed from the controller.”

        Note that my initial my plan is to use the Arduino only to control the auger, governing the speed of the pellet feed. The hot rod (igniter) only has to come on for the first 4 minutes the grill is switched on, and the fan is currently on 100% of the time, so I can leave those two running off the existing manual controller.

        Once I have got auger control working, I can add a couple more relays and some additional code, and move the other two components to my home-made controller – there is something to be gained by reducing the fan speed on very low temperature cooks (which none of the commercial controllers do, strangely enough).

        At that point I can remove the manual controller, and perhaps replace it with some kind of LCD display, again running off the Arduino.

        But that bit is way off, if not a mere pipedream.

  4. chris
    May 12, 2011

    Heh. I don’t think I have ever been so leading edge before.

    Google have just announced an “Android Open Accessory Design Kit”, and it is based around Arduino.

    • chris
      May 12, 2011

      Re: Bluetooth cooking thermometer

      Yep. I’ve got essentially the same functionality (but not as cool) in this kit, which I own:

      http://www.maverickhousewares.com/et72.htm

      A transmitter and receiver, which gives you remote notification of both the grill and food temperatures from multiple probes. (or would, if the range was better).

      The integration into Iphone/Android is a nice touch, but the extra bang for buck my device will give me is that it will not just tell me what the temperature is, it will control it, without me having to do anything.

      Or, at the very least, until I perfect the automation logic, it will let me turn things up and down remotely, rather than running downstairs whenever the remote thermometer tells me something is going wrong.

      The choice between WiFi and Bluetooth is an interesting one. I think WiFi will give me much better range (and can utilise range extenders, if not), and also will mean I can use it from my desktop as well as the phone.

      However, Bluetooth would let me use Amarino (a toolkit to connect Android-driven mobile devices with Arduino microcontrollers via Bluetooth) for my interface, rather than developing a HTTP solution. Much cooler. If someone writes a WiFi extension for Amerino, I will be very happy.

      multicolor lamp using arduino, amarino and bluesmirf:

      http://www.youtube.com/watch?v=y19muoFia7M

  5. chris
    May 12, 2011

    And I’ve just had an email saying the kit is on its way to me. Rats, I am busy tomorrow, and have boardgamers round on Saturday. What’s the betting I’ll be up at 3am playing with the thing?

  6. chris
    May 13, 2011

    And it arrived today. As I say, I am busy tonight and tomorrow, but I still found time to take a look.

    Gosh, it is tiny! Originally, I thought it would be buried inside the grill (not the hot bit, obviously), but this would actually fit easily where the existing controller is. Put an LCD screen and some buttons on it, and you have local control, as well as remote.

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