Hacking a weighing scale

Last couple of weekends I mainly spent at home. This was ideal opportunity¬†to do some home maintenance (cleaning ūüôĀ ). Somewhere under the bed I found a weighing scale that my wife and I occasionally use. This is the simple digital weighing scale from Ikea – GRUNDTAL. During last months I stumbled¬†upon couple of articles¬†about automatic weight logging, so the outcome was obvious: the next home project – wireless logging weighing scale. Luckily I already had necessary¬†tools and parts, so the next couple of days were fun.

IKEA GRUNDTAL Weghing scale

The idea was to connect the scale to Arduino Pro Mini, decode the readings from the scale, and send the weight wirelessly, using RFM12B radio module from HopeRF, to the central Homy system. There, the weight with the timestamp would be persisted into the database and published to Facebook wall.

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Homy and plants

After having all the light bulbs in the house under control, I couldn’t resist electrifying the rest of the household ūüôā I spent couple of days looking around the house, and finally found the next “thing” to experiment with.¬†Couple of months ago my wife and me got a¬†Dracaena tree. Since we had no experience in nursing the plants, we had some doubts about when and how often to water it. I decided to solve this problem in geeky engineering way.

After some online investigation on how to measure a “water level” for the plant, I came across some nice articles:¬†How to make a cheap soil moisture sensor?,¬†Gypsum Blocks / Electrical Resistance,¬†Moisture Sensor Prototype, … It was clear I would need to build a gypsum sensors myself, since it was cheaper and more fun. After quick visit to the nearby hobby shop, all necessary tools and materials were at the table: nails, gypsum, thick paper…

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