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Garden/Greenhouse monitoring
02-27-2013, 06:06 PM,
#1
Garden/Greenhouse monitoring
For a while I have wanted to get together an environmental monitoring system for our home greenhouse that my dad and I built last winter.

As I remember, at our first meeting, Nathan mentioned a similar project involving outputting a data log of conditions, which I would like to work in as well. I went ahead and ordered some Arduino compatible parts (soil hygrometer, Temp & humidity sensor) and plan to get something basic thrown together soon. Aynone else interested and/or care to collaborate?
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02-27-2013, 06:11 PM,
#2
RE: Garden/Greenhouse monitoring
(02-27-2013, 06:06 PM)tupperck Wrote: Aynone else interested and/or care to collaborate?

I would be interested in helping as I could, also Pete mentioned he would like to do something like this also at the last meeting
-Dan

"If you didn't build it, you will never own it." - Barton Dring
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02-27-2013, 10:43 PM,
#3
RE: Garden/Greenhouse monitoring
Stumbled across what looks to be a very pertinent site: http://gardenbot.org/
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03-11-2013, 09:05 AM,
#4
RE: Garden/Greenhouse monitoring
Initially, my rough thought for a system like this is essentially what is shown on that garden-bot site: a pc in the house tied to sensors out in the garden for soil conductivity, soil temp, RH, and temp at the bare minimum. Other features I would like but are not strictly necessary include a water valve controlled by the system, and a way to open the vents in the greenhouse when it's getting too hot inside.

It seems like Raspberry Pi would be an ideal control station for the whole system. Is it possible/simple to build a sensor station using an Arduino and necessary sensors, and then tie that (wireless?) to a RPi that is used to control the whole system? The controller and sensor station would only be about 12 feet from one another, through one exterior wall. I like that the RPi would give the possibility for a gui without needing to have a dedicated PC in my house just to do the gardening stuff.
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03-13-2013, 09:10 AM,
#5
RE: Garden/Greenhouse monitoring
When I had originally heard of this idea, I thought it would be a perfect candidate for SPI.

One arduino or other, could be used to control an instrument cluster, there could be a large number of these all chained up to the master unit that would control everything. For a small garden it would only need a master and a slave, for a larger setup it could be one master with many different slaves.

There are some downsides to spi but it seems to be rather simple to use
-Dan

"If you didn't build it, you will never own it." - Barton Dring
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03-13-2013, 11:08 AM,
#6
RE: Garden/Greenhouse monitoring
One thing that is essential from my perspective is making it so that all of the data can be very easily put onto a computer. That's my dad's main problem with current systems out there: they all force you to use their base station and you can't just pipe the data to your computer. Being able to get the data onto a computer makes it so you can run all sorts of analysis and such, which is super useful. It would also open another opportunity for the company making the hardware: writing up a good software suite to go with it.
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03-13-2013, 12:25 PM,
#7
RE: Garden/Greenhouse monitoring
SPI is good for very short distances, like between devices on a PCB. CAN is better for longer distances because of noise immunity (error correction). http://www.ni.com/white-paper/2732/en

Atmel has CAN-bus built into some of their processors, so you could build a board and still utilize the Arduino language for programming, or you could add a SPI-CAN chip like on this board:
https://www.sparkfun.com/products/10039 CAN would allow you to string a bunch of devices together, because they can be daisey-chained on the same bus. So you could have a 4-wire cable that provides power and communications out to several devices.

Ethernet (hardwired or wifi) is the best option if you want a bunch of devices that can talk to anything directly without a base station, but it will add to the cost of 'slave' devices and also to the complexity of the board (you have to pay special attention to trace routing). You can buy a Power-over-Ethernet Arduino board now though: https://www.sparkfun.com/products/11230 Combine the POE board with an 8-port POE switch and you could have multiple sensors up to 100 meters from the switch with one cable. Ethernet is also the best option for high bandwidth or high-speed data requirements (which you won't need unless you want to drop a video camera on the same monitoring network).

Bottom line (in my experience and without doing much research), CAN is probably the cheapest option but would require upfront engineering to figure out the firmware and hardware required.
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03-13-2013, 07:13 PM,
#8
RE: Garden/Greenhouse monitoring
Maybe we could build something with a base station where the base station has removable storage, so that if you want to load the data onto a computer you can simply unplug the storage (flash drive or whatever) and plug it into your computer? Alternatively, have a base station with wifi capability so that the additional cost and complexity is limited to just the one location?
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03-14-2013, 08:37 AM,
#9
RE: Garden/Greenhouse monitoring
I like that idea of removeable storage; the CAN-BUS shield linked to above seems to have an SD slot for data logging purposes. Not sure if logging to onboard storage vs a remote computer would require more complex software, but the ability to log the data permanently is important to me as well.
I imagined a computer base-station that was tethered via ethernet or something to a sensor station. The POE arduino/switch option David mentioned makes me think ethernet would be worth a try. If using some arduino for the sensor station, I think it would be simple to output readings sporadically and have them written directly to a spreadsheet or SPSS file for easy analysis.
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03-14-2013, 09:00 AM,
#10
RE: Garden/Greenhouse monitoring
I was re-reading your original comments. Since you aren't going to have a lot of sensors, you can probably just use a single Arduino with sensors wired to it, and then get data from it via USB (12 feet is reasonable for USB).

I think you can probably read the data to the Rasperry Pi over USB from the Arduino. For longer distances you could use a simple serial connection (RS-232) - you might need to add some additional circuitry but nothing too difficult.

As long as you don't need a 'star' configuration where you have one base station with a bunch of data collectors (Arduinos) off of it, you can use point-to-point serial communications just fine. Data-rates are still measured in kbps for serial.
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