hi Jane, Hi Michal,
I agree with both Michal and Jane #1 :)
The important issue is not merely soil humidity, not whether the sensor to LED path is analog or digital - my digression with Morgan. The issue is as Michal pointed out -- reminding us of when a particular plant needs water. The delay, or anything requiring some memory is a good case for digital computation. (this is a deep practical difference between analog and digital computation)
And yes, I think it makes sense to go with Jane #1, always: people's knowing habit, tacit knowledge, is always infinitely nuanced and richer than any systematized schematized knowledge. A "scientific" study could work, but it takes years of study to get beyond naive hacker amateur, who is less reliable than either gardener or mature botanist. There's need to systematically get a degree in botany when Jane and Laura already know plants down to your fingers :)
(Mike Cooley, in Architect or Bee, has a thoughtful section about craft vs modularized info, and the mill wright.)
Xin Wei
On 2011-03-17, at 11:35 AM, jane tingley <janetingley@yahoo.com> wrote:
Hi Xin Wei - this mail was sent out - you were CCed but it bounced back...Hi everyoneMichal brought up a good point.As a recap - we discussed having a little analogue circuit on the humidity detector that has a POT ( a dial that we turn to either increase or decrease the detection of humidity) So we put it in the plant when it is dry for example, to set the sensitivity. We also discussed whether we should send the info to the arduino, and have the arduino turn the LED on and off.so//there are two approaches we could take ...1) Intuitive/tech2) Science/tech1) If we have a side circuit that controls the led, with a POT - then basically, when either Laura or I put the sensor in the plants, we dial the POT to adjust sensitivity. We will use our knowledge of the plants to calibrate these sensors over a period of say a month. So for example - With a yucca - a desert plant and generally needs a little bit of water every two weeks. Let's say the green LED comes on in the yucca after just 1 week of being watered, and the plant looks healthy, we would dial the sensitivity lower. We would do this until the light goes on after what we believe - based on our knowledge of plants - is an appropriate amount of time. This approach would be more intuitive, and require a couple of people who are knowledgable of plants to set up the system - as well as a lengthy calibration period.2) We find out the actual science - what exact level of humidity a yucca needs to survive. Send the data out to a computer, and then have the program turn the LED on when the plant needs to be water - based on the science. We could then also use this data to take care of the plants during the summer.Perhaps people have some opinions about which direction we should take. I'm on the fence.
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Sent: Thu, March 17, 2011 10:09:31 AM
Subject: Re: Links from PLSS Meeting (Electronics)Hi all,Regardless of the microcontrollers/hardware and connectivity issue, I
too have some thoughts about what we discussed yesterday. Going back
to the design of electronic circuit that includes indicators (LED) for
the plants, I think that the original idea of having a LED controlled
by the program/firmware, is in fact more appropriate one. This is
because the plants need to be watered not only according to the
moisture level of the soil but also according to their needs (desert
plants can last a long time in dry soil). This aspect should be
controlled either by the microcontroller or, preferably, a computer
program, which would be adjusted according to what kind of plants are
hooked up into the system. In that case, a LED will go on only after
a certain time interval that the soil would have been dry. I am not
sure about the analog dial (pot) for the circuit. For a standalone
solution (microcontroller only) it would make sense to have some
relative control. If this is going to be hooked up to a a computer
anyways, we could foresee programming a user interface which will
allow for specifying some kind of conditions per plant (I suppose this
would be preferred solution).I hope I am making sense, please let me know if I am off the track
(wrt PLSS philosophy) or if something is unclear.BestMichalOn Wed, Mar 16, 2011 at 11:51 PM, Morgan Sutherland
< wrote:
> Hello Jane,
> If we want to use Ethernet rather than USB, I recommend using this WIZnet
> module which has an associated Arduino library so development is
> trivial: http://arduino.cc/en/Reference/Ethernet
> If you want to trade money for time, you can get the Arduino Ethernet shield
> (yes, it's compatible with the Seeeduino Mega), which is the same Wiznet
> chip: http://www.sparkfun.com/products/9026
> There are four advantages to ethernet that I can think of:
> (1) the cables are cheaper and you can make them to the exact length you
> need
> (2) there is no cable length limit
> (3) if the cable is accidentally unplugged, you don't need to restart your
> software in order to re-establish a connection, it's just always pushing the
> data onto the network without any "hand-shaking" required and
> (4) if we connect it to a switch (like the one on Michael's desk) the data
> is available to any computer in the lab – that would be useful for a day in
> the future when my computer is not located near the box.
> The downsides:
> (1) more development time
> (2) $30 extra
> I'd be curious as to why you were recommended another ethernet solution
> since this one is proven to work well and has an easy to use library.
> Morgan
> On Wed, Mar 16, 2011 at 6:21 PM, Morgan Sutherland
> wrote:
>>
>> Hi Jane,
>> Silicone conformal coating for protecting circuits from water:
>>
>> http://www.abra-electronics.com/products/422B%252dP-MG-Silicone-Conformal-Coating.html
>> The microcontroller we have + will use:
>>
>> http://www.seeedstudio.com/depot/seeeduino-mega-p-717.html?cPath=80&zenid=22b1d4d04f39a87446605e3c6bf360ef
>> Morgan
>