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Makahiya – first tests

Hi everybody,
During this second part of the week, we had the opportunity to test several components of our project.

First, on Thursday, I tested the capacitive proximity sensor with a coaxial cable (~ 50cm long) and an aluminium plate. By chance, it worked immediately: no parameter tuning was needed on order to detect the proximity of my hand, in all directions and even through a 3cm wood table. Friday evening, I decided to do the same test but with a real plant this time (the calathea I’ve already told about before). I attached the coaxial cable to a leaf with some scotch and once again, it worked perfectly !! I was able to see how close my hand was from the leaf. And if I approached my hand of another leaf, it was not detected, which is good if we want to turn each leaf into a separate button (this is probably due to the fact that on the calathea, each leaf has a separate trunk) We can thus definitely validate the choice of this component.

On Friday, we received some of the components we ordered: the LEDs and all the stuff required to test them (resistors & transistors). We first tested the 2 types of LEDs with a laboratory power supply: they are really powerful, which is good. Then, we decided to try to control them with PWM. With a lot of help from Alexis, I soldered the different components required on the breadboard part of the Olimex P407 board while Tanguy wrote the code. First, it didn’t work and after some exploration, Alexis found a short circuit between 2 pins. Once it has been removed, it worked perfectly well. We had time to test only one of the 2 LEDs. Before taking the final decision about the leds, we want to test with the optical fiber. This will be done as soon as we receive it.

Next week, we have to do the schematic of our board. And I would like to write some code in order to detect how close my hand is from the sensor (up to now, I’ve just visually analysed the graph).

PS: I forgot to say, I’ve bought a new plant yesterday: a banana tree. I hope this species will move less than the Calathea. Answer on Wednesday.

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