{"id":6461,"date":"2016-04-25T12:42:06","date_gmt":"2016-04-25T12:42:06","guid":{"rendered":"http:\/\/notmart.org\/blog\/?p=6461"},"modified":"2016-04-25T12:42:06","modified_gmt":"2016-04-25T12:42:06","slug":"making-or-watering-plants-the-complicated-way","status":"publish","type":"post","link":"https:\/\/notmart.org\/blog\/2016\/04\/making-or-watering-plants-the-complicated-way\/","title":{"rendered":"Making (or, watering plants the complicated way)"},"content":{"rendered":"

This post wanders quite off topic… but has a lot of pretty pictures indeed \ud83d\ude09
\nSometimes I ask myself why I am a software developer, the answer in the end is that I always enjoyed creating things, whatever it is going from being sketched out totally in my imagination to finally seeing it in the flesh. Writing software, especially graphical software can be very satisfying exactly because of this mental process of seeing the thing you thought about slowly forming and starting to actually working, with the gap between the mental image and the real thing narrowing more and more (yeah, I’m one of those heavy visual thinkers that can think almost exclusively by images).
\nBut sometimes nothing can replace the satisfaction to create an actual, beautiful object, and I also feel manual skills are something that we should cultivate much more, I feel more complete if every now and then I do something that a) I don’t know anything about when I start and b) it’s a difficult manual skill to craft.
\nThat’s also why before drawing the svg for the Kirigami<\/a> banner
\n\"kirigami\"<\/a>
\nI “had” to make some experiments of an actual kirigami…
\n\"kirigami\"<\/a>
\nBut this post is not about that.<\/p>\n

Almost a year ago, a friend of mine told me that he wanted to learn a bit to hack on some simple Arduino stuff, and you know what? I wanted too.
\nI have this stubborn quality that makes me to go quite overboard when I decide to do something (especially if is not for myself) and not to stop until is done<\/em>, actually useful<\/em> and pretty<\/em>, so if we are doing some Arduino project, let’s do something that has an use and that will be pretty… and that’s how the project “Bagnur” started (means watering can in Piedmontese language).
\n

\"logo\"<\/a>

Of course<\/strong> it needed a logo :p<\/p><\/div>
\nThe project is one that is seen again and again on the interwebs, so is just a remix of existing ideas rather than something truly innovative: the Arduino takes data from a soil moisture sensor (different humidity in the soil changes current conductivity), to figure out how much water the soil of a potted plant has.
\nWhen is dry enough it opens a solenoid based valve to pour enough water in, and the moisture sampling goes on and on, hopefully stopping you from killing those poor potted plants from thirst after forgetting watering them for days \ud83d\ude09<\/p>\n

\"IMG_2869\"<\/a>

The final hand made steampunk-like package<\/p><\/div>\n

The moisture sensor is based on the LM393 chip<\/a>, the solenoid valve is similar to this one<\/a> (hilariously overspec for this project, love this kind of overkill).<\/p>\n

So we know the Arduino output pins have a too weak current to operate the valve, it will have to be powered separatedly: the Arduino will close its circuit with a transistor, I had just salvaged an E13007 NPN transistor<\/a> that had useful charateristics (low base-emitter saturation voltage, resists quite heavy loads) from a broken ATX power supply.
\nThis makes things a bit more interesting, luckily in the end a single power source was enough to power the Arduino and the valve in parallel, probably not particularly recomended, but cheap and compact (having 2 different power bricks for such a sillyness wouldn’t have been particularly fun for day to day use).<\/p>\n

To make the project a bit more interesting, we have a potentiometer that will regulate how much water the plant needs, different plants, different needs and one of those pretty RGB LEDs, that will be the “output UI” of the thing.
\nThe state of the led will be:<\/p>\n