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Old 06-03-2012, 01:54 PM   #11
Elkoe
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Nov 2011
Eindhoven, Noord-Brabant(NL)
Posts: 84
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Current setup for UberFridge is:
Arduino runs low level temperature control (predictive on-off with PID for the fridge setting), Arduino reads temperatures and drives the LCD display.

The router (linux) runs a python script, which periodically asks the Arduino for data and logs this into JSON and CSV files. This script also verifies the Arduino temperature settings and updates these according to the temperature profile in a Google spreadsheet.

The web server on the router (lighttpd) just provides the web interface. It reads the JSON files from disk and can also communicate directly with the Arduino through a socket. Settings are updated by sending commands though this socket.

Example: To display the LCD text, the web server asks python for the LCD data. Python asks the Arduino, Arduino asks the LCD display. All responses go through the same chain. It's quite a complex communication chain, because of the many layers involved.

The arduino connects to the Pi through USB. With a USB hub in between, it should be possible to run multiple python scripts, all monitoring a different serial port. Multiple Arduinos, one web interface.



 
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Old 06-03-2012, 03:10 PM   #12
cobolstinks
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Sep 2008
Rochester, MN
Posts: 229
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Quote:
Originally Posted by Elkoe View Post
Current setup for UberFridge is:
Arduino runs low level temperature control (predictive on-off with PID for the fridge setting), Arduino reads temperatures and drives the LCD display.

The router (linux) runs a python script, which periodically asks the Arduino for data and logs this into JSON and CSV files. This script also verifies the Arduino temperature settings and updates these according to the temperature profile in a Google spreadsheet.

The web server on the router (lighttpd) just provides the web interface. It reads the JSON files from disk and can also communicate directly with the Arduino through a socket. Settings are updated by sending commands though this socket.

Example: To display the LCD text, the web server asks python for the LCD data. Python asks the Arduino, Arduino asks the LCD display. All responses go through the same chain. It's quite a complex communication chain, because of the many layers involved.

The arduino connects to the Pi through USB. With a USB hub in between, it should be possible to run multiple python scripts, all monitoring a different serial port. Multiple Arduinos, one web interface.

I a have something similar setup. I have a netduino that listens on a socket for Ajax requests from a simple HTML page. Then it reads 4 1-wire sensors and returns json. Works pretty well thus far.

To the OP. Sorry to be negative but I see a couple of major hurdles in your plan. 1market, lets face it your product will be marketed to a tiny population of people. I think the avg Brewer isn't going to want to mess will a incorporating a micro controller on their here's rig.2 aclick once install is going to be difficult to accomplish. People are going to have several premeatations of wireless networks, brands of routers, security protocols, etc.

Good luck



 
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Old 06-03-2012, 04:36 PM   #13
idiosyncronaut
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May 2012
Chicago, IL
Posts: 47
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I love the idea, this sounds like a phenomenal project.

Any thought to using Ruby?
__________________
Primary - Zombie Reagan (single hopped citra IPA, take #2) [Batch #3]
Bottled - Ancient of Days - (american pale wheat ale) [Batch #2]
Bottled - Zombie Lincoln (single hopped citra IPA) [Batch #1]

 
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Old 06-03-2012, 05:16 PM   #14
carlisle_bob
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Apr 2012
Carlisle, PA
Posts: 1,205
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Hi

USB is indeed an easy thing to tie stuff together with. It has a few odd little quirks that might get in the way on some applications.

Signaling is all done against a common ground. That can be an issue if systems get large. Power switching and the like can create ground bumps..

USB self protects in case of an over current (or what it *thinks* is one). With some devices the only way to clear the fault is to unplug it. That's not really what you want in the middle of a control system.

Stacks for USB aren't enormous, but on a bang for the bytes basis, you are not getting a lot here. As you point out, it's pretty layer intensive for a simple single controller serial i/o application.

Finally, USB has some line length limitations. In a compact setup that's not an issue. If I want to have part of the system in the garage and the rest in the basement, it would be an issue.

By no means take any of this to mean it won't work. It will indeed work, but there are some tradeoffs. I don't know of any way to do this that does not have some tradeoffs.

 
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Old 06-03-2012, 05:36 PM   #15
Elkoe
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Nov 2011
Eindhoven, Noord-Brabant(NL)
Posts: 84
Liked 29 Times on 17 Posts


Quote:
Originally Posted by cobolstinks View Post
I a have something similar setup. I have a netduino that listens on a socket for Ajax requests from a simple HTML page. Then it reads 4 1-wire sensors and returns json. Works pretty well thus far.

To the OP. Sorry to be negative but I see a couple of major hurdles in your plan. 1market, lets face it your product will be marketed to a tiny population of people. I think the avg Brewer isn't going to want to mess will a incorporating a micro controller on their here's rig.2 aclick once install is going to be difficult to accomplish. People are going to have several premeatations of wireless networks, brands of routers, security protocols, etc.

Good luck
I know the market is not that big. It don't expect to get rich from this and I don't even expect to pay my bills from this project. It should just bring in a bit of money that justifies the time I put in. The first group of brewers will be geeks, but when it gets a bit more mature it should not be difficult to set up.

A one click install script should be possible by sticking to the Raspberry Pi. You just connect the Pi to the Internet and do an aptget and run an install script. Connecting it to your home network of course needs a bit of manual settings, but not that much.

 
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Old 06-03-2012, 05:39 PM   #16
Elkoe
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Nov 2011
Eindhoven, Noord-Brabant(NL)
Posts: 84
Liked 29 Times on 17 Posts


Quote:
Originally Posted by idiosyncronaut View Post
I love the idea, this sounds like a phenomenal project.

Any thought to using Ruby?
I have zero experience with Ruby, so I used Python, PHP and jQuery.

It is indeed a phenomenal project, but I had many positive reactions to my survey (allmost 100 people fully filled it in) and many people want to contribute to the code.

 
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Old 06-03-2012, 11:54 PM   #17
rpfuror
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Jan 2010
MD
Posts: 54
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I defiantly like the idea of having a .deb package that will load all the binaries/scripts to run the programs/demons. If you need any help with the linux/perl (as that's my language of choice)/python side of thing let me know... I can get thru most of it.

I have been looking at the raspberry pi since I heard about it and I'll get one as soon as I can.

 
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Old 06-04-2012, 09:37 PM   #18
Heckle
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May 2009
Hartford, Connecticut
Posts: 256
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Subscribing.

 
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Old 06-04-2012, 10:12 PM   #19
xrattiracer
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Jun 2012
Seattle, WA
Posts: 17

Browsed through this and filled out the survey.
The one thing that comes to mind as far as connecting things together would be to use CAN bus, its made for that exact purpose.

 
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Old 06-04-2012, 10:57 PM   #20
carlisle_bob
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Apr 2012
Carlisle, PA
Posts: 1,205
Liked 29 Times on 28 Posts


Hi

CAN (and it's little brother LIN) are indeed bus alternatives. They are lower overhead than USB. They aren't quite as good for long distances as some other alternatives.

Bob



 
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