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Makahiya: components and first gifts

Hi everybody,

First of all, I want to give you some news about the plant I bought last saturday. It’s pretty nice and would have been perfectly tailored for our project except for one detail. Indeed, unfortunately, it moves its leaves alone: from horizontal during the day, they go vertical for the night. This video shows it very well. So this plant will remain in my living room and we will have to find another one for our project. Maybe another Calathea or a banana tree (provided we manage to find one in Paris or nearby).capacitive-sensor

On a more technical point of view, this week has been dedicated to the choice of the components, because nothing else can be done before. I’ve searched an appropriate capacitive proximity sensor and found 3 possible ones. Alexis helped us to do the final choice by quickly eliminating the 2 first, because of the sensor design needed. So, we’ll use one from TI (FDC2214). In order to check that it can do the job, we ordered an evaluation board with this component. We received it Friday morning and I tested it Friday evening. The result is quite impressive, even if I haven’t done any tuning yet (see the image on the right)!!

For the ligthning, I called 2 companies (MidlightSun & Luxeri) to ask them about what they can propose us. Midlight Sun is too expensive but Luxeri isn’t. So we’ll order diffusing optic fiber. We don’t know what diameter to choose as they have from 0.25 to 2mm. If possible, we’ll order a sample of 1mm and one of 2mm of diameter to test which one is the most suitable. In order to illuminate them, we have to find a proper RGB LED, but we have no idea of the required power. I’ve found this one and this one which seem rather powerful. A test will be needed to choose.

For the other components, we’ve chosen:

  • for moving the leaves, we’ll use Flexinol (also called muscle wire), a wire that shortens when heated.
  • for communication, a Wi-Fi module (Zentri AMW007)
  • a portable speaker (many exists, so we’ll take the easiest to find nearby)
  • an audio codec (TLV320), found by Tanguy

Next week work:

  • test different sensor shapes for the capacitive sensor and tune the settings
  • order samples to test (optic fiber and LEDs)
  • select a processor
  • decide if we add BT (or BLE)
  • select a battery (if possible, because it depends a lot on the LEDs we’ll choose)
  • start the PCB design

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