Arduino+XBee Dual-stage Temp Controller

Who doesn't need a wirelessly-controlled fermentation fridge? Figured it'd be the bee's knees for automated temperature ramps when lagering.

This logs data to and can be controlled from my Linux server (Debian). Records ambient air, ambient fridge air, and carboy temps (carboy sensor taped and insulated against outside of carboy). Serial XBee input is read by a 13KB C-based Linux daemon that parses, validates, and publishes the XBee packets to interested clients via TCP/IP. A PHP-based logger script "subscribes" to the stream, only listens for packets from the fridge, and shoves them in a MySQL database where it can be graphed through a web browser (facilitated with PHP and JPGraph).

Temperature control is based on carboy temps. Cold stage controls fridge power, hot stage controls Flex-Watt heat tape. Built-in time protection for shortcycle delays.






I used an RGB LCD display so it turns blue when cooling, red when heating, green when temp is within setpoint, and a weird purplish color when off.






In this graph, the setpoint (orange line) was changed to 45F and control turned on. The dark blue line indicates when the fridge was being powered. Tested with a can of paint thinner ("carboy" temp is bright green line). Kept temps to +/- 1 degree. After the last power cycle, it was turned off. The light blue line is the ambient air swing of my shop heater; you can see at the end of the fridge power that the ambient air swung to 50F - had to open the shop door to vent engine fumes. Door was closed and the ambient swung back up, then gradually declined. Hard to see in the compressed graph, sorry.




Will be testing with a real carboy and heat tape possibly this evening. Will be interesting to see how well it controls it.

I know it's only a matter of time before someone says that I could have used a Fermtroller.

Before you do: I don't care.

Cheers!

Looks great! I've got something similar, but the variable backlight colors on the LCD is very cool.

Thanks!

I would love to see some plans, Might be over my head.

Nice! The only thing to make it better would be Slackware!


Oh, forgot to ask if you have a link to a large image.

Thanks!

No, I don't have links to larger images; Photobucket scales them down.

Schematic is super simple. Instead of using expensive SSR's which aren't necessary anyway, I picked up a very cheap dual-relay controller off eBay. It was like $8 with shipping from China!



Temp sensors from Adafruit. https://www.adafruit.com/products/165

Chuginator said:

Schematic is super simple. Instead of using expensive SSR's which aren't necessary anyway, I picked up a very cheap dual-relay controller off eBay. It was like $8 with shipping from China!

Click to expand...

Can you post a link to the relay controller you got?

nice to see some Arduino projects around here. im doing the exact same thing at the moment with an Uno, only not wirelessly as i have ethernet ports all over the house already. im also using some solenoids to control coolant circulation from my glycol chiller to the three zones that it supplies (kegerator upstairs, ferm chamber and keg chiller in the basement).

if you ever need any relays, shields, etc... this place is the tits...
https://arduino-direct.com/sunshop/
slow shipping, but priced right.

also check out www.bwired.nl for some web interface inspiration. that guy went all out with home automation.

MalFet said:

Can you post a link to the relay controller you got?

Click to expand...

Sure thing!

http://www.ebay.com/itm/Arduino-Dua...ltDomain_0&hash=item2a0fd6485d#ht_1437wt_1165

audger said:

nice to see some Arduino projects around here. im doing the exact same thing at the moment with an Uno, only not wirelessly as i have ethernet ports all over the house already. im also using some solenoids to control coolant circulation from my glycol chiller to the three zones that it supplies (kegerator upstairs, ferm chamber and keg chiller in the basement).

if you ever need any relays, shields, etc... this place is the tits...
https://arduino-direct.com/sunshop/
slow shipping, but priced right.

also check out www.bwired.nl for some web interface inspiration. that guy went all out with home automation.

Click to expand...

Hey, coolness!! Thanks for the links!

Chuginator said:

Sure thing!

http://www.ebay.com/itm/Arduino-Dua...ltDomain_0&hash=item2a0fd6485d#ht_1437wt_1165

Click to expand...

Very cool, thanks.

You can of course build the equivalent with discrete components but this was already on a board, assembled, all ready to go - the cost was so small that I took my time into account and figured... what the hell, I'll let the Chinese do that part for me.

I would like a link to the cool LCD display and maybe some software information.

Wow I wish that dual relay board had 20A or 40A SSRs instead of 10A. That thing is pretty awesome.

What are your costs on the hardware ?

really cool, thanks for sharing.

Homercidal said:

I would like a link to the cool LCD display and maybe some software information.

Click to expand...

LCD display: http://www.adafruit.com/products/399

What would you like to know about the software?

weirdboy said:

Wow I wish that dual relay board had 20A or 40A SSRs instead of 10A. That thing is pretty awesome.

Click to expand...

What would you be needing 20A SSR's for? Industrial fridge of some sort?

adam01 said:

What are your costs on the hardware ?

Click to expand...

I think right around $90, not including the XBee receiver on the server (that was leftover from my sprinkler controller project). Definitely didn't do it to save money, I wanted remote logging and control.

android said:

really cool, thanks for sharing.

Click to expand...

Thanks, and you betcha!

Exactly what I've been looking for. ALready have the Arduino and LCD. Any link to the code?

Hey Chuginator, what are you using for graphing software?

I built a setup using the ethernet shield that broadcasts temperature data to my webserver, which stores it in a database. The trouble I am having is displaying the large amount of data that it collects in a reasonable fashion.

Chuginator said:

What would you be needing 20A SSR's for? Industrial fridge of some sort?

Click to expand...

Not a fridge, a HERMS.

CoalCracker said:

Exactly what I've been looking for. ALready have the Arduino and LCD. Any link to the code?

Click to expand...

That's left as an exercise to the developer. Post if you have questions or troubles with any specifics and I'll put some routines up for you.

Brewbs said:

Hey Chuginator, what are you using for graphing software?

I built a setup using the ethernet shield that broadcasts temperature data to my webserver, which stores it in a database. The trouble I am having is displaying the large amount of data that it collects in a reasonable fashion.

Click to expand...

I'm using PHP and JPGraph. The MySQL query I'm using is:

$query = "SELECT unix_timestamp(datetime) as datetime, onoff, mode, setpoint, ambair, ambfridgeair, carboy FROM log WHERE datetime >= date_sub(curdate(), interval 6 hour) ORDER BY datetime ASC";

This pulls out the data (which is being logged once per minute) for the last six hours, then it's pumped through JPGraph.

And I thought I was cool for building an analog temperature controller from scratch... Nicely done.

SkiNuke said:

And I thought I was cool for building an analog temperature controller from scratch... Nicely done.

Click to expand...

Dude, you ARE cool for building an analog temperature controller from scratch.

And thank you.

Do you have a link to your build?

Amongst all this digital stuff, I do have a warm spot in my heart for good old analog. Analog reminds me of vinyl records, large discrete components, Nixie tubes, speakers, and hot electronic smells that a lot of whippersnappers might never smell or get burned by. Good stuff.

Wow. I didn't even understand most of the OP. But this is wicked awesome.

ChandlerBang said:

Wow. I didn't even understand most of the OP. But this is wicked awesome.

Click to expand...

Thanks, man! Sorry, I tend to get way too technical. Simply put, it's a home-brew temp controller for my fermentation fridge, with the added benefit that my computer can control and log data remotely from it.

I'm pretty impressed with the range on the XBee's. Even within that enclosure, I'm getting updates once a minute reliably, from about 100' and going through three walls. I wish they were a little cheaper (they're about $20 each), but I ask myself if it's worth $20 to keep an eye on things remotely, and it is to me. Particularly in the test phase to see how well the temp control code is performing in reality, and how my free fridge is keeping up (or not).

Chuginator said:

Dude, you ARE cool for building an analog temperature controller from scratch.

And thank you.

Do you have a link to your build?

Amongst all this digital stuff, I do have a warm spot in my heart for good old analog. Analog reminds me of vinyl records, large discrete components, Nixie tubes, speakers, and hot electronic smells that a lot of whippersnappers might never smell or get burned by. Good stuff.

Click to expand...

I haven't yet uploaded anything from the build since I only finished it maybe 3-4 weeks back. I plan to make a how to and put it up on my website, but I will try to remember to post a teaser when I get off of work. I'll post a link here so you can check it out.

Chuginator said:

That's left as an exercise to the developer. Post if you have questions or troubles with any specifics and I'll put some routines up for you.

Click to expand...

Darn, I can wire and do the electronics... I lack skills in programming. Even though I've taken a fair share for C courses in college. Barely made it out of them.

This is a great DYI! AWESOME job with this...

CoalCracker said:

Darn, I can wire and do the electronics... I lack skills in programming. Even though I've taken a fair share for C courses in college. Barely made it out of them.

Click to expand...

If you want to get skilled at programing get the Arduino and try something out you want to do. Thats the problem with college, unless it is your passion some courses are tough just because you don't have the same drive to learn it because it is not presented in an interesting way
Thats why the Arduino is good, you get to learn programing (with a fair bit of help - check out the Arduino forum) and it is interesting.

CoalCracker .. I have a EE and struggled with C in college. The arduino uses "wiring" which in my opinion is the dummies version of C. If I can do it ... just sayin

My level 1 and 2 C++ classes I passed with b's level 3... damn near flunked. I can do HTML so I"m not totally inept when it comes to programming, just not good at it.

CoalCracker said:

Darn, I can wire and do the electronics... I lack skills in programming. Even though I've taken a fair share for C courses in college. Barely made it out of them.

Click to expand...

No worries man, there's light at the end of your tunnel. There are examples all over the Internet if you're interested in your own implementation.

For example, here's how to read the temp sensors: http://www.ladyada.net/learn/sensors/tmp36.html

rekoob said:

This is a great DYI! AWESOME job with this...

Click to expand...

Thank you!

Chuginator said:

That's left as an exercise to the developer. Post if you have questions or troubles with any specifics and I'll put some routines up for you.

Click to expand...

This is awesome!!! I'm curious though, why are you not willing to share your code?

Kosch said:

This is awesome!!! I'm curious though, why are you not willing to share your code?

Click to expand...

Thanks, man!

Not willing to share code because it is art. If I threw you everything I have, it wouldn't be unique.

Give me your questions on code, I will try to help you think it through. But I won't throw you a solution.

Interestingly enough, I'm an open-source advocate. Go figure.

Plus, it's near 800 lines of C for the Arduino. Can't even post it here (10K limit).