Homebrew pit controller

[nwaring]

So, be gentle with me as this in my first post on the forum.

Just wanted to share eperience with the community about Homebrew controllers. I'm not sure if you've ever seen the thread on TVWBBB (http://tvwbb.com/eve/forums/a/frm/f/5561094836). It's a bit of a long read but after a fun couple of weeks gathering components I now have a working Pit controller with WIFI control and up to 3 food probes.

All in it's probably cost about £100 (it aleard had probes from ET732 which are compatible) and has been worth the effort. I am now able to sleep relatively peacefully whilst doing a long and slow.

I'm in the process of taking some photos and will update if anyone is interested in learning more.

Nick

[Steve]

That's a great thread. One of the other guys has built an Arduino based controller for a pellet smoker.

My next project is a Raspberry Pi based controller, that will give me the remote control over WiFi. however it's one for Winter, when hopefully I can get a Raspberry Pi

[nwaring]

Bryan and some others have started to think about the next generation which will use a Raspberry Pi - I agree with you - getting hold of one is proving time consuming.

In the meantime, the 'Linkmeter' uses a Linksys WRT54GL as the 'host' - this allows you to wirelessly control the pit temperature, see how much the blower has been on and view the progress of the cook.

[KamadoSimon]

I'm in the process of taking some photos and will update if anyone is interested in learning more.

Nick

Definately interested Nick - was thinking about a Stoker at some point in the future, but i'd rather build one if someone has a good how-to!

Cheers,
Simon

[nwaring]

Hi Simon,

There are far too many posts on the forum... distilling down to the real information is a nightmare!

However, as part of my build I have written up a build guide which will eventually be upladed onto the WIKI pages which support the endeavour.

If you let me know your mail address I can mail you a copy of the current draft.

Nick

[Chris__M]

That's a great thread. One of the other guys has built an Arduino based controller for a pellet smoker.

Waves

I think there are at least two of us here.

At the present stage, I still haven't spent any time on the actual PID-like code for it. My halfway house (originally intended for testing of the hardware) gave me the ability to both monitor the temperatures and control the pellet feed timing remotely over my network. As virtually all of of my low-and-slow cooks are during the day, when I am working in my office upstairs, this has proved to be all I needed. If I see the smoker is running cool or hot, I can tweak it from my desk, plus I am not restricted to just the three feed levels of the 3-way controller.

I do still intend to write auto-controlling code, but it is not a priority. What is more of a priority is soldering the pins up and putting it in a box, as - a year later - I am still using it assembled on a breadboard.

For times when I am out there cooking with guests (burgers, steaks etc), I don't even bother with my controller. I just unplug it, and the grill reverts back to the 3-way.

My next project is a Raspberry Pi based controller, that will give me the remote control over WiFi. however it's one for Winter, when hopefully I can get a Raspberry Pi

The moment I heard of the Raspberry Pi, my first thought was "shall I dump my Arduino and start again"? No good reason to, other than "new toy" appeal.

However, when I checked (and I admit it was only a cursory check), I thought I confirmed that the Raspberry Pi only has digital input/output onboard, and for analog I/O (i.e. for input from temperature probes), you would need to buy and add additional kit. Unless I am mistaken, of course, which is very possible.

On the other hand, the Arduino has a surfeit of both digital and analog I/O, and all you need to connect a standard probe is a suitable resistance from the analog pin to ground. My initial design had one grill probe and three food probes, although I have only implemented one of each so far.

So while the Raspberry Pi gives you the luxury of a full Linux server to play with, and a multitude of programming languages, the Arduino makes the hardware design a lot simpler, in my opinion.

However, I'm not saying the Raspberry Pi shouldn't be used, as I am extremely interested in what folk will come up with!

[nwaring]

Hi Chris,

I don't have any experience of controlling pellet smoker... my controller is really an alternative to a Guru or Stoker and is just about maintaining temperature.

It took me a while to understand that the project is about two things:
1. The "Heatermeter" a separate board which takes the Probe inputs and controls the fan based on the PID theory. This used to be built using an arduino but is now a custom designed PCB (with Atmega chip)
2. The "Linkmeter" which is when a "Heatermeter" is integrated with a Linksys router to get WIFI and web access to the HeaterMeter

Take a look at the TVWBB forum - there is a separate thread on developing the Rasbperry Pi version. As I understand this is likey to still use some / much of the "HeaterMeter", but remove the need for the Linksys router.

It may also be worth looking here https://github.com/CapnBry/HeaterMeter/wiki... it's where all the code (inc PID theroy) etc is located.

Nick

[Chris__M]

I don't have any experience of controlling pellet smoker... my controller is really an alternative to a Guru or Stoker and is just about maintaining temperature.

It's a similar but not identical problem. Whereas you are controlling the temperature by controlling the airflow, in a pellet grill you do it by controlling the feed of pellets through to the burnpot. Which essentially means turning a relay on and off that controls the pellet auger's motor.

The standard way to do this appears to be to remove the existing manual controller and replace it. Instead, I put my relay in series with the existing 3-way controller (smoke/medium/high). When I want to use my controller, I connect it to the relay using a flying lead, and switch the 3-way to high (so it is always on), and thus my controller is controlling things. When i don't want to bother with my controller, I unplug it (or simply don't power it), and the original 3-way controller is in control. Keeps it simple, and means that (a) once the relay was in place, there is no further need to constantly rewire things (b) if something goes wrong (hardware/software) with my controller in the middle of a cook, I have the 3-way to fall back on, instantly, as I have the relay defaulted to "on" (rather than "off", as is more common). This has never happened, but I am belt-and-braces man.

I'd come across the LinkMeter design before - but the rather complete thread you linked to seems to post-date my initial research, so thanks for that - I'll take a look at the code sometime, and see if there is anything I can use/adapt.

My original plan involved WiFi, either with an Arduino WiFi shield, or something like the LinkMeter. Then I resited my BBQ, so it is on the opposite side of a garage wall to where I have my backup PC sited (I work in IT, and from home, so I like to have out-of-the-house backup storage). So all it took was a hole through the wall, and I had a standard network connection, which made the design heaps simpler (and cheaper!). So my arduino is connected to the physical network, and can be accessed from my desktop, or my laptop/android phone via the network's wifi.

This is one of the reasons why I stopped posting about my project, as it turned into very much a personal solution, rather than something that might be useful to share with others. The whole design is based on decisions and compromises I am content with, but others might not find useful. That, and the fact that a year on and it is still a work-in-progress.

[nwaring]

Understand a bit more now - just been on the Traeger site to find out more - I liked the "why I love my Traeger" video on the front page!

With a cabled connection things do become a lot easier. The Linkmeter did start off using a WIFI shield but there was a good reason (can't recall what it was) as to why it was dumped in preference for the Linksys router... the next development will integrate with the PI, but that's still only about improving network connectivity.

Nick

[Chris__M]

I forgot to say. The main difference between controlling a pellet grill and a blower system, is that with a blower system, you are working with small voltages, to run a DC blower fan. However, the auger motor that feeds the pellets in is AC mains electricity (240V, or 110V in the US), which means the turning things on and off become more complicated (and potentially dangerous, if you don't know what you are doing). Add to this that the motor can actually produce reverse spikes in your circuitry, which you need to protect your relay against.

I did this by buying a relay with the protection circuitry built in. This is a separate little component board fitted to the grill itself. So to the Arduino, all it is is a digital line to be on or off.