Homebrew pit controller

[aris]

So you are using the chamber probes? I think it would be quite cool to use multiple chamber and multiple food probes.

[Chris__M]

Yep. At the moment I am using one pit probe and one food probe, although my script allows for up to 3 food probes.

My understanding is that the pit (chamber) probe and food probe are the same inside, and so have the same parameters.

Note that the ET-732 probes (also on sale at that site) have different properties, which I don't have details for. Everyone seems to be using the ET-73 ones.

[aris]

You said you need a resistor on the VCC line for those probes - what value?

I got my arduino today - got my basic 'hello world' blinking LED working. I also have it running off a 9v battery which will be handy when used outdoors locked in an IP65 container.

I'm considering adding one of those LCD screens with buttons on it - they are also quite inexpensive and it would be nice if you could set the high and low temperatures.

[Coot]

If you've not seen these they are handy little systems http://mbed.org/

[aris]

Looks very powerful indeed, but way more expensive than the Arduino, and to be honest possibly a bit of an overkill for the application

[Coot]

Good alternative to the Pi's though, with a proper set of pins too

Interesting project you have going on, will keep an eye on it.

[Chris__M]

You said you need a resistor on the VCC line for those probes - what value?

Take a good look at the schematic at http://hruska.us/tempmon/ which will show you the arrangement of the probe, analog pin and resistor to VCC.

With regard to the value, most people appear to have been using 22K, but I am using 10K, as I had them already. Within reason, the value doesn't matter, as long as it is in that kind of range. The value of the resistor is in the Arduino code, set to Rknown, so you need to change that value to whatever you need.

More importantly than the actual value, I'd advise to use a 1% (tolerance) resistor, rather than the cheaper 5% ones.

[aris]

Ok thanks - i think I got a good idea of what to do now.

I just ordered a shed-load of various sensors for the Arduino. My kids and I will have alot of fun playing with these!

One of the things I ordered was a bluetooth adapter. It was remarkably cheap and attaches to the Arduino serial port - so in theory I can send serial data to my PC or possibly even an android device (or perhaps a Raspberry Pi). All very exciting!

[Chris__M]

Sounds good.

This is more or less why I abandoned any attempt at a generic pit controller routine; in that there are so many different ways to get the info out there, all perfectly valid. Some folk are using WiFi via wifi shields, at least one person is using Xbee to connect their Arduino to a PC (and I believe the control routine is happening at the PC end), and then there is Bluetooth. My method uses an Ethernet shield to connect to my Lan network, from where I can access it either through my PC or (via my WiFi router) my Android phone. Still others are doing it all locally, with switches and LCDs.

All of these approaches need different bits of code, and if you are not careful, the code starts to dictate the physical device. So I think it's better to simply share the general information, and let people roll their own devices. Aside from anything else, I think people get more sense of achievement, and understand their controller better.-

[aris]

Well said. By the end of this I may well have spent the same as if I bought soething, but would be vastly less fun.