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 Post subject: Raspberry PI
PostPosted: Thu Jan 24, 2013 12:14 pm 
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Joined: Fri Nov 30, 2012 1:54 pm
Posts: 275
http://www.raspberrypi.org

I don't know too much about this MC, but it looks like a power house for media connectivity with a lot of RAM compared to the Arduino. The thing what's lacking for me is support: code, examples, and tutorials. I'm on OS X so not sure how that works out.


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 Post subject: Re: Raspberry PI
PostPosted: Sun Jan 27, 2013 12:30 am 
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Joined: Sun Jan 27, 2013 12:03 am
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It is very powerful. I have some friends that are using it in a startup company that builds remote controlled submarines (cool project BTW PM me if anyone wants to know about it as I don't want to derail the post). It's cheap and powerful, but like you said it's lacking code, examples, and tutorials. Part of this is because it hasn't been widely available until the last few months.

The bigger issue is that many wouldn't really count it as a MC, its a full on computer. That opens a lot of doors and then closes others. This means you have to load an OS on it, and then write and compile your programs for that OS with all the libraries and extra support you need for any attached hardware. Not to say it's impossible, but it has a much higher barrier to entry compared to arduino, PIC, or the TI Lanuchpad.

The little I have played with it, you have to load an OS (usually linux/unix variation) onto an SD Card. From there you have console access through HDMI and USB keyboard, or if you enable it you have remote shell access over the network. I haven't gotten past that part. I thought about picking one up just to have another nerdy thing to play around with when I'm bored, someday.


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 Post subject: Re: Raspberry PI
PostPosted: Sun Jan 27, 2013 10:38 am 
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Thanks for some info on this. It wasn't an easy find.


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 Post subject: Re: Raspberry PI
PostPosted: Wed Feb 13, 2013 9:57 pm 
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The PI made the news
http://news.yahoo.com/blogs/this-could- ... 27303.html


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 Post subject: Re: Raspberry PI
PostPosted: Sat Feb 23, 2013 11:31 am 
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Joined: Sat Feb 23, 2013 11:03 am
Posts: 13
Hi,

I'm new to this forum, just found it.

I'm using a Raspberry Pi to monitor/control a 75 gal freshwater planted Discus tank and in particular an Aquamedic NR Blue nitrate reactor. Looking at the Adafruit Peristaltic pump to control the flow into the reactor instead of the current solenoid-based solution. Concerned about noise, reliability, and ability to withstand pressure (the reactor is underneath the tank, hooked up to the output of a canister filter with the valve on the input to the filter).

If anyone is interested or has experience with this device, let me know and I'll post more details.


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 Post subject: Re: Raspberry PI
PostPosted: Sat Feb 23, 2013 1:25 pm 
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Joined: Fri Nov 30, 2012 1:54 pm
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doninla wrote:
Hi,

I'm new to this forum, just found it.

I'm using a Raspberry Pi to monitor/control a 75 gal freshwater planted Discus tank and in particular an Aquamedic NR Blue nitrate reactor. Looking at the Adafruit Peristaltic pump to control the flow into the reactor instead of the current solenoid-based solution. Concerned about noise, reliability, and ability to withstand pressure (the reactor is underneath the tank, hooked up to the output of a canister filter with the valve on the input to the filter).

If anyone is interested or has experience with this device, let me know and I'll post more details.


Please show your work. I'm super curious about the PI now.


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 Post subject: Re: Raspberry PI
PostPosted: Sat Feb 23, 2013 4:20 pm 
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Joined: Sat Feb 23, 2013 11:03 am
Posts: 13
OK - here goes...

- Raspberry Pi revision B
- Raspbian OS (latest - i keep this updated)
- 8Gb SD card
- USB wifi dongle
- ads1115 i2c 4-channel ADC (for temperature probes)
- 2 Adafruit thermistors (water and filter temp)
- 2 Jeelabs relay boards for controlling ORP valve, lights x 2
- Adafruit 16x2 I2C LCD backpack with 5 buttons
- Aquamedic ORP probe (in NR Blue nitrate reactor)
- Atlas Scientific ORP board (serial interface)
- "wiringPi" library to handle the I/O on the Pi
- Apache to run the web server
- PHP and HTML for the web pages
- MySQL 5.5 for the database to hold control data and measurements
- pchart for charting the data
- libesmtp for sending emails
- various miscellaneous code I've found and adapted to read the ADC, talk to the serial port, LCD, etc.

I've written the control code in C since that's the language I'm most comfortable with (but rusty :-)), and I'm using PHP for the web pages. There is a bunch of Python code for the Pi but that language gives me the creeps, so I've stayed away :-).

I've currently got a control loop that runs every 5 seconds, reads the inputs, checks for exceeded limits, and implements the control algorithm for the filter. It averages the readings over 10 minutes and records the data in the database. This loop also re-reads the control info (ORP setpoints, loop times, min/max alarms, etc) from the database every 10 minutes. If limits are exceeded, it sends me an email (but not more than once per hour per condition).

There are curently 3 sets of web pages:
- one to allow me to specify a charting interval (last N hours or start/stop date/time) and then shows a chart with the temperature, valve on/off data, and ORP level over time.
- one to allow me to update any of the control parameters
- one to allow me to turn off/on either of the two sets of lights (these are otherwise on a schedule using the Linux "cron" facility) .

I have a Mac and installed an AFP file service on the Pi so i can attach the Pi's file system to my Mac, and I use the Mac's XCode environment to edit. Then i SSH into the Pi to compile and run.

That pretty much covers it...

I just got the LCD going so I'll integrate that shortly to display the current metrics. There are some buttons on it as well but I'm not sure what I'll use them for yet :-). I'm sure I'll think of something...

Right now everything is on a big breadboard sitting under my aquarium - at some point I'll solder everything to a more permanent board.

Oh - the aquarium has 7 4" Discus, some dwarf Plecos, 9 Nerite snails, a few Amano shrimp, and is planted. This whole project is a result of my desire to minimize water changes by using the Nitrate reactor. I don't want to start a flame war here about that, so lets just leave it at that. But I needed a system to control the flow into the Nitrate reactor based on the ORP level within, and commercial units cost about $500 by the time you are done with the controller, pump, valves, etc. Thus the DIY effort... plus my wife said I needed a hobby.


regards
Don


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File comment: 75 Gal planted tank with 7 4" Discus
DiscusTankSmall.jpg
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 Post subject: Re: Raspberry PI
PostPosted: Sat Feb 23, 2013 7:55 pm 
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Joined: Fri Nov 30, 2012 1:54 pm
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Very nice. I'm a Mac guy too. Can I use objective C to code the PI?


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 Post subject: Re: Raspberry PI
PostPosted: Sun Feb 24, 2013 1:22 am 
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Joined: Sat Feb 23, 2013 11:03 am
Posts: 13
Not sure - you'd either need an Objective C compiler that runs on Linux, or a way to compile the code on the Mac to run on an ARM processor...


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