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Computer-based mostly-self-contained intermittent mist system

Posted by bwaynef z7 SC (My Page) on
Fri, Jun 20, 14 at 10:51

Years ago I became fascinated with the idea of propagating woody plants (trees mostly) by cuttings. Naturally the ones I was most interested in propagating are some of the most difficult; pines for instance. Intermittent mist is heralded as increasing the percentages for many species so off I went looking into setting something up. The timer, being the most important piece, was unsurprisingly the most expensive for what I wanted to be able to do: essentially have no limits as to how often or how long I could have the mist on. Accepting ANY limitations would've made the potential ready-for-purchase systems a bit more affordable, ...but I wanted to tinker. Also, I didn't want to have to tap into my plumbing, ...and would like for this to be portable if needed so I can run the propagation chamber in my greenhouse or in my garage under lights.

Here's my system:
1 Computer: I chose a Raspberry Pi ($35, ...plus memory card, case, wireless adapter ...so closer to $60-75 ...although I had one that wasn't being used.)
1 X10 firecracker home automation set (serial dongle and switchable outlet/receiver)
1 Weed Sprayer --http://amzn.to/1qm6WEh or similar
1 solenoid --http://amzn.to/1jD2LP6 or similar (plus a transformer that outputs appropriate voltage. I was able to "repurpose" one.)
Mist heads, tubing, and appropriate connectors -- Rainbird/Toro/MrDrip

I snipped the wand off the sprayer and connected that to the input side of the solenoid valve. I connected the mist/tubing stuff to the other side of the valve. Wired the solenoid to the transformer. After filling the sprayer up and pressurizing it, I plugged the transformer in and had mist.

Now, this is where I'll likely diverge from most users who follow after me. The Raspberry Pi isn't a magic bullet. Its small. Its cheap. And its powerful enough to do what I need (...and replaced 5 linear feet of computers on a shelf in the garage I was holding onto in case I wanted to do something like this. Not bad for a computer I can carry in a shirt pocket.) You can use whatever computer you have that has a serial port on it. If it doesn't have serial, you can buy a USB-serial converter (...which I should've included in the list above, since the RasPi only has USB). If your computer runs Windows, the X10-supplied software should run on it and you'll have to follow its documentation to schedule the mist.

I'm running Slackware Linux 14.1. I found a software package called "bottlerocket" that controls the x10 firecracker module and receiver. Executing bottlerocket, br, with the address of the receiver and a simple command, on or off, turns the device on or off. I created a
"br address on
sleep 10
br address off"
script. That script turns on the mist, waits 10 seconds, and turns off the mist. I called that script "mist.10" You ought to be able to extrapolate how to mist for longer and shorter than the 10 seconds I've demonstrated.

I then add a cron entry, Linux' timing/automatic-program-execution facility. Currently, I've set the mist to come on every 30 minutes for 10 seconds from 7 am through the 12pm hour. Then from 1p to 7p it comes on every 10 minutes for 10 seconds.

The crontab entry looks like this:

# Intermittent Mist
*/30 7-12 * * * /home/username/mist.10
*/10 13-19 * * * /home/username/mist.10

(Cron entries have minute, hour, day of month, month, and day of week. The asterisks tell cron to execute it regardless for that time period.)

An additional x10 receiver and a solenoid are all that's necessary to expand the system. Simply call br with the different address of the receiver and you're controlling a different "zone".

I also dabbled with a temperature/humidistat, although I never was able to get it calibrated to my liking. The temperature, at summertime daylight hours, was ~10�F higher than my wireless thermometer sitting directly above the humidistat. Also, the relative humidity read significantly lower than I believed it to be. The idea being to measure the humidity and, if it fell below a threshold, turn on the mist to increase it. Also, if the temperature was exceeded, the mist would bring it back down. That script was more complex ...and I may revisit it ...but we're going on vacation tomorrow and I needed to get this set up for several cuttings I have taken in the last week or 3. (Ginkgo seedlings ...as cuttings *10, Trident maple *32 and Japanese Maple 'Shishigishira' *10)

For some of you, this is needlessly complex. I like to tinker and had most of these parts on-hand when it occurred to me that I could do this so it didn't cause an outlay of cash quite like buying a similarly capable timer would have.


Follow-Up Postings:

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RE: Computer-based mostly-self-contained intermittent mist system

bway,
how is it working for you?
care to post a pic of the set-up?
i am collecting info as i want to set-up a sensor driven automated computer system in the future for lighting/watering mostly (misting probably too), when i have a proper space for it. not a full blown green-house style, but smth that can be set up in various tiled areas (like a sun-room/patio) and monitored over the internet, perhaps too.
smth amateurish and not too expensive. and i like to tinker.
as far as temp/humidity measurements - you need to calibrate sensors with a couple reg std devices for accuracy. the thermometer has to be in the shade and not picking up any heat from other exposed surface - any sun/exposed dark surfaces will raise the reading . and you can't really estimate humidity by feel, so don't rely on that.
was curious, whether you plugged it in other computer to configer/enter parameters.
wiki'ed it and got:
Whereas the majority of Linux systems boot into a graphical user interface, Slackware's default user environment is the textual shell / command line interface.
-- text shell would obviously be an advantage to keep it simple.
is that why you chose slackware?
so was yours outside (i see it can overheat over 85F?) or in the garage? how did you handle lighting?
what about gertboard for sensor i-face? that could be handy?
and camera/ethernet adapter, etc - the whole could be monitored/switched online. seems doable?
i foresee extensive travel in the future with remote gardening enabled set-up ;)


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RE: Computer-based mostly-self-contained intermittent mist system

I chose Slackware because I've used it for most of about 15 years. Once its set up, I don't usually have to fool with it. (That said, once I plugged in my x10 module and started switching the solenoid on and off, I'd not be able to get into the system. I believe it was still operational, but there is apparently some memory leak in the usb system or the x10 application that makes it so that I can't connect. As a result, I've set the Raspberry Pi to reboot every 3 days-ish. I'll let it run like this until I have time to replace the x10 part of the system with a PiFace module I've bought and not had time to dive into. Also, I've had 900+ days of uptime on (a different box running) Slackware before, so I'm confident the problem is in one of the programs in use.)

It turns out that I got started too late in the year to have much success, ...and when I did try, I'd set myself up for failure by going out of town the VERY NEXT morning after I'd set this up. Alas, my neighbor who was checking in on things missed the instruction for this system so...

I've iterated away from the spray tank and its need of constant filling and pressurization. I've connected garden hose to the solenoid w/ a connector that can be had @ Lowes (garden hose to pipe thread). Its now truly set and forget.

I'm able to access the device remotely via ssh anywhere I have internet. Its also set as a webserver, but I don't have current data being displayed any longer. I was graphing temperature and humidity in my greenhouse as well as the closest weather station. It wouldn't be hard to build some sort of webpage to control it, but that's not exactly my strength (...but might make an interesting project).

As far as calibration, I spent about 2 weeks calibrating it. Its "offness" wasn't linear and the output from the tool provided by the author of the software didn't seem to handle it much better. In an effort to get a usable product, I've scrapped the temperature/humidity sensor controlled parts until such time as I can get better data from them. (This might mean new sensors, or more refinement in calibration.) The system is now only using time as input into when it should mist. I think its set for 10 seconds every 2 hours at present.


I managed to get a few Japanese Maple, Juniper, and Crabapple cuttings to root, and I've got a flat of ~90-ish gardenias under mist right now. Hopefully next year I can get started early and in earnest ...and really put this system through its paces. My primary concern is in the finding of interesting stock to root. Also, if a copy of any of Dirr's propagation manuals comes around I might see about acquiring it. I still need to contain the guts of this system in a project box of some sort for a few different reasons. If I can find the time, I may build out benches for my greenhouse ...and see about installing a heating cable.


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RE: Computer-based mostly-self-contained intermittent mist system

there was a post in houseplants recently: some computer guys wanted to set up an indoor computer driven system as a project. perhaps they can recommend better sensors for you?

there'salso a lot of info on misting in rose propagation FAQ, but not as far as the computer set up goes though. but it might be of some use to you.
they seem to think that 'patio-style' misters not for horti-use are very good for intermittent mist, providing very fine mist, not spray.
http://faq.gardenweb.com/faq/lists/rosespro/2003063646004668.html

Here is a link that might be useful: post in houseplants


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