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-   -   TeensyPi Networked Temperature Controller (http://www.homebrewtalk.com/f51/teensypi-networked-temperature-controller-375635/)

jimmayhugh 12-21-2012 04:58 PM

TeensyPi Networked Temperature Controller
 
I've got my latest networked temperature controller up and running, it's a Raspberry Pi board interfaced with a Teensy 3.0 32-bit ARM Cortex mini-board that allows you to monitor and control up to 36 1-Wire temperature sensors and switches in up to 12 different actions. It is capable of running on both wired and wireless intranets. The Teensy 3.0 is capable of using many of the Arduino libraries, and can be programmed with a modified Arduino IDE, making it a snap to use.

The Teensy 3.0 handles all of the sensing and control, and the Raspberry Pi interrogates the Teensy 3.0 about every 500 milliseconds and updates a web interface to show you the current status. The Raspberry Pi uses a LAMP stack to handle the database and web processes, so you can add or change programs in whatever language suits you. I use PHP and Javascript, but you could also use PERL, Python, C, whatever floats your boat :D

Once the Teensy 3.0 is setup, it can run autonomously, with no interaction from the Raspberry Pi. It will resume its last settings in the event of a power failure, with no input from the Raspberry Pi. The Raspberry Pi is solely for setup and display purposes.

I've started a Blog that outlines the parts and steps required to make your very own TeensyPi, and am in the process of designing a board that will replace the current Adafruit Pi Plate.

I haven't gotten the pages done for the sensors and switches yet, but they should be forthcoming soon.

Hope this is of some interest. :mug:

stlbeer 12-21-2012 05:59 PM

Definite interest from me! I've been reading about the Pi and am about ready to buy.

Soapebrews 12-22-2012 11:56 PM

I've read up on these Pi's and was going to use one with a touch screen in my car(1991 Stealth) but it NEVER occurred to me to use one in my brewing.....Please update often sos I can get one going for myself....

kladue 12-24-2012 02:49 AM

I salute your efforts, way beyond just a basic RPI setup seen on this board. Your efforts with the Teensy 3.0 have answered a lot of the questions I had with the Cortex M4 hardware and it's suitability for process control. While I am not headed in the 1wire hardware direction you have brought all the needed aspects together for the rest of the people, and have given them a road map, and software to make it happen.
I am interested in watching this effort grow and expand, and am curious as to where you will draw the line with function and display scope creep, and say this is enough.

starman 12-25-2012 12:23 AM

Sub'd. I love all these sorts of build threads but this one really matches what I'd like to do.

Excluding the central boards/controllers, what is your approx hardware cost per 1 sensor, 2 stage zone?

jimmayhugh 12-25-2012 04:58 AM

Quote:

Originally Posted by kladue (Post 4711535)
I am interested in watching this effort grow and expand, and am curious as to where you will draw the line with function and display scope creep, and say this is enough.

That's always the rub, isn't it? :D

The Teensy 3.0 has lots of oomph, and the fact that it's able to use or port many of the Arduino libraries makes it very easy to add other bells and whistles (PID, flow sensing, local display, etc), and the display side with the RPi can also handle local data logging, and other functions.

For now, I'm going to concentrate on the basics.

jimmayhugh 12-25-2012 05:07 AM

Quote:

Originally Posted by starman (Post 4713531)
Excluding the central boards/controllers, what is your approx hardware cost per 1 sensor, 2 stage zone?

I picked up 50 of the DS18B20 Digital Thermometer chips for about 85 cents each with free shipping on E-Bay and built my own probes with spare phone cords and ethernet cables that I scrounged for free. I'll be posting a blog page on that in the future. You can also purchase pre-made probes from Brewers Hardware, Adafruit, and others. Cost per probe is in the $10-$20 range.

The DS2406+ chips were about $3 each from DigiKey, and I've made a little circuit board that will work with up to four 25A SSRs. Also to be posted in an upcoming page.

jimmayhugh 01-04-2013 01:46 PM

Update
 
As part of my on-going testing and validation, I've breadboarded 12 temperature sensors and 12 switches:

http://www.teensypi.com//images/TwelveEach.png

As a precaution, I've added a 3v3 / 800ma voltage regulator to the board to supply the current to the additional sensors / switches. It's probably not necessary if only a few sensor / switch combos are used, but I prefer to understress my components.

More info is available at my website.

starman 01-05-2013 01:18 AM

Thanks for the update. Do you think it Is OK to pick up SSRs without heatsinks for say a lager chamber?

jimmayhugh 01-05-2013 05:26 AM

Quote:

Originally Posted by starman (Post 4748375)
Thanks for the update. Do you think it Is OK to pick up SSRs without heatsinks for say a lager chamber?

I'm probably the wrong person to ask, as I tend to over-engineer things :D

I use the 25A-40A SSRs for everything, and heat sink most of them, either by attaching them to a metal enclosure with screws and thermal grease (my pumps), or a big honking heatsink (my RIMS).

I prefer to under-stress my equipment as much as possible.


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