[Help needed] Electronics/PCB: Building a cheaper / diy BrewPi

[pob]

Warning: Long techy thread with potential boring bits & images

I'm looking for help from any tech heads out there, to check my circuit diagram for my Arduino integrated version of the BrewPi shield. After looking at the BrewPi schematics, I want to build a few boards to try it out. It won't look as neat as the purchased item, but should still work the same. I'm looking at making option (3), see below (I have option (2) working at the moment, want to make a standalone version for non-network users).

I'm looking for feedback on how it looks, any pitfalls, recommendations. After only picking up a soldering iron after 20 years I know the actual build needs lots practice ;-). I will just use some prototype boards initially, but may even looking at getting boards made up, cheaply from China. If it works, I'll put a few together for anyone interested.

So if you could help, I'd appreciate it. (I need to potentially add a buzzer & LEDs, not essential but...)






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Background: The BrewPi is an open source project that uses a RaspberryPi & an Arduino with multiple temperature sensors & relays/SSRs for Heating & Cooling, to allow better control of your fermentation fridge/chamber (its a smart STC 1000 type controller).



Ignore gap between 8th & 9th May, I was playing with the shield & probes, Green trace is beer temp, Blue trace is ferment chamber's temp (I've hidden the other traces so you can easily read it). I only have heating tube in an insulated chamber at the moment, 2nd fridge needs to be sourced next.



The brewpi.com can be used in a couple of different formats.

The Arduino is the actual PID controller, it runs the script which does the temperature control, typically keeping either your beer or your fridge at a constant temperature. It uses a PID monitoring system to estimate where the heating / cooling needs to be, while keeping the beer at its set temperature.  It runs a display & selector button (rotary encoder) to show you current temp of the beer & the fridge, and the temps they should be at.

The Raspberry Pi adds a web interface, data logging & control,which allows you to get fancy with multi temp fermentation profiles, e.g. Lager - first 12 days at 12C, rise to 18C for 2 days, slowly drop to 2C over a week, keep at 2C for 4 weeks (quite specialised, too much for most). The Raspberry Pi also connects to your network to allow remote access & monitoring (worldwide if you set up port forwarding on your router).

I have borrowed (big thanks) & used the purchased version, which can be purchased online from brewpi.com, it is a very good product but not cheap, so I was looking to produce something similar for a lot less & make a few extra up for other NHC Brewers.

The BrewPi can be used in a couple of different formats. I have the circuit diagrams from the BrewPi website & put together a bare version (with Raspberry Pi & Arduino) which is working nicely at the moment.



There are 3 useful ways to do it (you could also run it completely bare without any display, set it at your desired temp & hope it doesn't fail, very brave and whereas it should work you'd have no way of knowing if there was a problem - so very cheap but not really practical and contradicts the reason you have of using a monitored temp control).

(1)  Full control:



Both physical & remote access: buy all the bits from BrewPi (~€200),  works well, looks great but very expensive.



(2)  Remote access only (~€75*):



Use a RaspberryPi (~€40) & Arduino (€10-€15) without display or rotary encoder, set it up to use the web interface only to control settings (i.e. PC, laptop, iPhone, etc) - cheaper but need to link it to your home network (Wifi or LAN required). (* still need 2 x SSRs & 2-3 DS18b20 Temp probes) - this is the version I'm currently using.



(3) Physical access only (~€45, all in one box): This is the bit I need help on.



Use the Arduino only with a LCD & rotary controller, this only allows fixed temp setting (either beer or fridge), restricted by not having a programming mode, but most simple and likely the option needed by 90% of users. Once the Arduino is initially programmed from the RaspPi,  you can unplug it from the RaspPi and let it run on it's own, e.g. set it at 18C - Beer Constant.

When you add in Arduino Uno (€10), LCD (€5), probes (€8), SSRs (€8), 12V Converter (€5), enclosure (€10) you could probably get it down with a quantity buy & eBay to <€40, really not much more than a STC1000, but would give you a better / more consistent temp control of beer.

Thermowells are the expensive bit, Carboy Stopper Thermowell $24 from States, working on a much cheaper alternative (still stainless) at the moment.

Remember: It won't make your beer better, just adds better control of one of the variables.


(Edited: relinked photos)

[nigel_c]

MMMmmm Raspberry  pi 

[imark]

I've a headless brewpi I put together myself. I've noticed the apache server on the pi craps out after a while. A reboot fixes it. I wouldn't be arsed with the lcd and encoder. You can put a thermometer in the fridge - simpler.
For static temperature control the stc controllers do the job nicely and cheaper.
So in conclusion, I think the headless version for complicate fermentation profiles is the way to go.

Good luck with the sheild and remember to keep it simple. 

[Ciaran]

I'm in the middle of trying to decide on what way to control a fermentation fridge.  I was going to go down the low wattage heat mat and stc1000 route as there's new firmware out which can create 6 time based temp profiles.

https://github.com/matsstaff/stc1000p

[imark]

That stc firmware looks interesting. I have a spare one here that I'll try it on in a few weeks.

[pob]

Looked at the STC1000 mod alright.

That was one of my options before the BrewPi.

Took my STC1000 apart & realised it looked very different to GitHub version, I've no header programmable pins, maybe a different version? (Can't read their board no, mine is 2009.06.20 V1.1).



Didn't bother trying to adapt after that, liked the idea though.

[JD]

Hi POB,

Interesting project. Just one thing about the circuit diagram: you seem to have not used any decoupling capacitors on the supply line going into the ICs. Something like 100nF up close to each chip will usually keep the supply free of transients. Everything will work without them but it's a reliability thing. Also, your PCB traces for power and ground are best made as big as possible. Same for anything carrying above a moderate current.

Apart from that, it's all looking good.
/J

[pob]

Thanks JD, I knew there would be smarter folks out there.

I'll add the 100nfs to the ICs.

First time playing with Eagle, I'm getting there slowly.

I think I can add in thicker power tracks and a big ground plane at the end, it makes it harder to view diagram when still planning.

If there was enough demand (& it worked), I might look at getting some made up (would need a redesign for smds) from China.

[pob]

EAGLE Lite PCB Software - Freeware version, some limitations (size 80x100mm & 2 signal layers)
http://www.cadsoftusa.com/download-eagle/?language=en

Took a few days playing around with it to work it out, first time using anything like this.

[Will_D]

I know we can get spam filters but what about "geeky interesting stuff" filters.

You have now totally wrecked my plans for the day. I will now sit in front of the computer reading about this and then dismantling my stc-1000s.

THANKS A LOT 

[pob]

I know we can get spam filters but what about "geeky interesting stuff" filters.

You have now totally wrecked my plans for the day.

'Day' you say, oh how I laugh. It's a total space-time continuum thingy, weeks if your lucky & can escape it's grasp.

Have fun, ;-)

[pob]

BTW the 328 has an inbuilt 8MHz oscillator. Slower but cheaper.

I was just copying the Arduino's schematic & adding it to the BrewPi shield. Possibly going to try building an integrated version.

Have just ordered some bits (capacitors, etc) to build a more robust DIY version of the RevC shield.

Original breadboard assembly works (just like purchased one when standalone), when connected to Raspberry Pi, it upset the LCD, needs the decoupling that JD suggested.

[ubermick]

So, bit of oul' thread necromancy - but working on a BrewPi shield over here, and about to fire it through the shaggin' window. Had it all wired and working, and the bloody potentiometer literally fell apart, and now there's no backlight. Would love to get my grubby paws on a premade model, but they're all gone, and DIY is currently the only way to go it seems.

[pob]

Why do you need the LCD display? Sounds silly but, if you are using the Raspberry Pi, it might just be handier using your phone/laptop to monitor it (just browse to the BrewPi's location, e.g. 192.168.1.22 and the RaspberryPi's webpage pops up).

If not, you just need a very basic shield (see BrewWiki).



LEDs not necessary, just to indicate when heating (red) or cooling (blue), to make sure SSR's are enabled correctly.

[neoanto]

This is pretty well laid out in a thread over on HBT
http://www.homebrewtalk.com/showthread.php?t=466106

I built this using a chinese aruduino knock-off and an old laptop.
I'd say it cost €60? Cos you need a few wires and resistors to put it together.

It's totally doable, going through the linux terminal is a bit of a pain but comes together in the end.
The only thing i'd say is watch out for dodgey USB cables. They can be the cause of the system not working and its hard to know.