raspberrypi expansion module

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symon_say
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Re: raspberrypi expansion module

Post by symon_say »

If i get hard wire internet, put my in, I hate the wifi module.
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00Warpig00
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Re: raspberrypi expansion module

Post by 00Warpig00 »

symon_say wrote:If i get hard wire internet, put my in, I hate the wifi module.
I'll second that!!
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bondolo
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Re: raspberrypi expansion module

Post by bondolo »

I am interested to hear more about mixing ra and pi as I have been playing with programming both.
rimai
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Re: raspberrypi expansion module

Post by rimai »

You could connect both UART ports together and use a java app on PI as a ethernet packet relay.
Technically, you could even run a remote shell to run avrdude and upload codes remotely.
Roberto.
Amos Poh
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Re: raspberrypi expansion module

Post by Amos Poh »

Looking forward for this to be in stores! :)
binder
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Re: raspberrypi expansion module

Post by binder »

has anybody made any progresson this? i ask because i own 2 pi's now and a usb wifi module for the pi. of course i have all of my extra ra equipment for testing as well. if anybody has anything coded up, please let me know so i can start helping out on it. who knows, maybe i can get what we want done for some remote programming or data logging or something.
dcartier
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Re: raspberrypi expansion module

Post by dcartier »

I did eventually get a Pi, but my unit proved to be flaky. It would only run for 10 minutes regardless of the power supply I used. I am just waiting to get another.

I started on a Python program running on a laptop over a FTDI breakout to the RA. I got it to the point where it could update the portal and was working on getting it handling requests from the portal when I got busy with work. Hopefully I will get back to it in the future and have something for when I finally get a working Pi.

Dennis
cypho
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Re: raspberrypi expansion module

Post by cypho »

I have been thinking about this more and begun to wonder about another approach to it, instead of having a PI talk to the RA head unit, could a PI replace the head unit entirely?

Is there any reason why one could not connect a RA expansion hub directly to a PI and then connect various RA Expansion Modules to the hub?
rimai
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Re: raspberrypi expansion module

Post by rimai »

You can do that too :)
Roberto.
thekameleon
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Re: raspberrypi expansion module

Post by thekameleon »

rimai wrote:Cool.
So basically, the first thing we need is to have some sort of java or any other application that would read UART and send it straight to the portal server. This would take care of sending data to server.
This is the easy part.
The more complex part would be incoming data. When someone connects to PI, we need the webserver to relay messages to RA over UART too.
So, let's say PI webserver is using 192.168.0.100 and port 2000 and you browse http://www.192.168.0.100:2000/ What PI needs to do is send GET / to RA via UART, read the response from RA and relay the reply to the browser.
Do you think you would be able to get this part done?
Would the easiest way to push the querystring to RA or instead create a Serial library that can read/write data in a simpler format?
rimai
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Re: raspberrypi expansion module

Post by rimai »

If you are trying to have a Pi module that replicates the wifi attachment, you need to make it as the Pi is a Serial to TCP converter.
Roberto.
rufessor
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Re: raspberrypi expansion module

Post by rufessor »

I too have been looking at the Pi... in terms of replacing the RA processor with the Pi- big issue is PWM output ... Pi has only 1 channel although there are some work arounds for this in software https://projects.drogon.net/software-pw ... pberry-pi/ but it eats clock cycles and of course uses up the other output pins... I believe I found a hardware (USB maybe) board that can interface for multi channel PWM ouput on the Pi but now its two pieces of hardware.. Would be nice to have something with enough PWM channels and outputs for everything else in 1 box... with internet!
Gotta love the memory though.
cypho
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Re: raspberrypi expansion module

Post by cypho »

rufessor wrote:I too have been looking at the Pi... in terms of replacing the RA processor with the Pi- big issue is PWM output ... Pi has only 1 channel although there are some work arounds for this in software https://projects.drogon.net/software-pw ... pberry-pi/ but it eats clock cycles and of course uses up the other output pins... I believe I found a hardware (USB maybe) board that can interface for multi channel PWM ouput on the Pi but now its two pieces of hardware.. Would be nice to have something with enough PWM channels and outputs for everything else in 1 box... with internet!
Gotta love the memory though.
How about this add-on chip. Adds 16 PWM channels should be more than enough.

http://www.adafruit.com/products/815
rimai
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Re: raspberrypi expansion module

Post by rimai »

Take a look at these:
http://www.youtube.com/watch?v=F-te4qkbh28
http://www.doctormonk.com/2012/04/raspb ... duino.html
The first one show the Arduino IDE running on the Pi and the 2nd one shows how we can leverage the wifi framework we already have and use Pi as a internet bridge.
We just need a python script, I guess... :)
Who know python really well?
Roberto.
rimai
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Re: raspberrypi expansion module

Post by rimai »

Ok, so I got my PI a couple days ago and here is what I got so far :)
http://i761.photobucket.com/albums/xx25 ... cb4643.jpg
Roberto.
dcartier
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Re: raspberrypi expansion module

Post by dcartier »

cypho wrote:
How about this add-on chip. Adds 16 PWM channels should be more than enough.

http://www.adafruit.com/products/815
Yep, those do work fine with the Pi. I have 2 of those hooked up to mine along with 2 x 16 bit GPIO, 1 x 12 bit 4 Channel ADC and 2 x 12 bit DAC for my 2 (soon to be controlled) WP40s. At some point the Pi will be hooked to the RA.

Which brings me to the reason I stopped by. I built an ATO/AWC with 4 water level sensors using the MPXV5004G chip. I noticed that the sensor in the sump seems to drift higher by 4% over a couple of days. If I lift the sensor from the water exposing it to the air, once submerged, the reading becomes accurate again. At first I though I had a leak that was allowing the water level to rise in my tube, but after thinking about it, that would cause the reading to be high, not low.

I am now leaning toward changes in barometeric pressure between when the sensor is lifted, and reset to ambient pressure, and when the ambient pressure changes over the course of a few days.

Is anyone using the RA version of the water level sensor seeing anything similar, and does the RA version take into account the ambient pressure at the time of calibration?

I am probably over thinking this. :?

Dennis
thekameleon
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Re: raspberrypi expansion module

Post by thekameleon »

Actually I think it could be an air leak. If you sensor is reading a higher water level, I think that means the air pressure exerted on the sensor by the water pressure would lower which should result in a higher water level. If you can use a clear plastic tube and see if water is climbing into the tube... It really shouldn't happen very much.
dcartier
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Re: raspberrypi expansion module

Post by dcartier »

That was my first thought as well. But the sensor is reading a lower reading after a few days when the water level is at the target. Unfortunately the sensor tube is CPVC, so it is opaque. I re-cut the end of the PVC hose that connects through a Watts connector to the sensor tube this morning, so we will see if it has any effect in a few days.

I am concerned as I don't want my AWC to increase the salinity over time.

The other long shot I was thinking of is micro bubbles that are traversing the baffle where the sensor is adding to the trapped air in the sensor tube. This seems like a very remote explanation though.

Dennis
dcartier
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Re: raspberrypi expansion module

Post by dcartier »

Actually I think I described it wrong. The sensor is reading higher, but the actual water level at that point is lower. So it is reading more pressure in the sensor tube then the water level would normally exert.

Dennis
rimai
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Re: raspberrypi expansion module

Post by rimai »

Wow... That was not easy... lol
But I finally got the Arduino IDE to compile our libraries.
I just didn't upload to test it yet...
The weird thing is that the compile size is very different...
Windows:
Binary sketch size: 42,588 bytes (of a 258,048 byte maximum)

Pi:
Binary sketch size: 40,464 bytes (of a 258,048 byte maximum)
Roberto.
dcartier
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Re: raspberrypi expansion module

Post by dcartier »

Just to follow up to my earlier posts so anyone finding this thread in the future can get the solution if they are having a similar problem. It turns out that it was in fact changes to the atmospheric pressure that caused my offset error. It manifested as the sensor reading either too high or too low over a number of days and usually after a shift in the weather.

What I did to overcome this was to add a Bosch BMP085 barometric pressure sensor to my bus. This allowed me to implement a calibration process where the atmospheric pressure is measured and noted while the sensing tubes are lifted out and exposed to the atmosphere. Then upon each reading of the level sensors, the atmospheric pressure is again measured and compared to the stored calibration value. I convert the BMP085 readings into kPa (the water level sensor uses 1v per kPa). The water level sensor value is then adjusted by 10% of the difference between the current and stored pressure reading.

I believe this works by accounting for the difference in the atmospheric pressure at the time of reading as compared to the atmospheric pressure (in the trapped air) when the tube was submerged. This appears to correct the offset error to within a millimetre or two, which is good enough for my needs. More testing is required to determine if the amount of offset error remains linear or if there is a boundary where this becomes problematic. I expect the summer storm season will provide some good test case large swings in barometric pressure to see if this works over the possible range of conditions.

Dennis
Atari
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Re: raspberrypi expansion module

Post by Atari »

Are they any updates on this concept yet? I have many plains for my RA that would having a Raspberry pi as a middle man would really help with.
The Idea that I was looking to and landed me here is, setting up a a ping monitor on systems around the house. I would be able to use this info to things like a power failures, then turn my MHs off to save power of the UPS, and email me to fix it.
rimai
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Re: raspberrypi expansion module

Post by rimai »

I have a PI that has a wifi dongle, so the only thing it needs is power.
I can remote control it with VNC.
I was able to connect the USB-TTL cable to the other USB port and upload codes to RA just fine.
Nobody created any software for PI yet though.
So, you would not be able to use the smart phone apps, for example.
If you can code python, you can create a program to link the serial to the Ethernet/wifi port. Want to try?
You may be able to do Java too, but I'm not sure.
Roberto.
Atari
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Re: raspberrypi expansion module

Post by Atari »

I don't program very well yet but here is something I found that might help.
http://www.buttcrackbrewery.com/2012/11 ... er-part-2/
rimai
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Re: raspberrypi expansion module

Post by rimai »

Cool.
Thanks for contributing.
This would solve the incoming portion of the puzzle.
We still need to push data to the Portal.
If you don't care about the Portal, this solution works fine :)
Roberto.
Atari
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Re: raspberrypi expansion module

Post by Atari »

With the RaspbarryPi running LAMP I was thinking that it would be the host for a private portal.
rimai
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Re: raspberrypi expansion module

Post by rimai »

Yes, it can.
And it would easily communicate with RA too with the zip files the author has provided :)
Want to try?
Roberto.
Atari
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Re: raspberrypi expansion module

Post by Atari »

I'm all about trying it. I just got to talk the wife into letting me get a Pi. It only took 2 years to get my RA :)
Atari
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Re: raspberrypi expansion module

Post by Atari »

I will get my Pi Friday!!! I'll be starting to play with it then.
rimai
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Re: raspberrypi expansion module

Post by rimai »

Roberto.
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