so today I finally finished to port my led driver to ChibiOS, you can find it on Github on the branch led
I also start to translate our wiki in english because we started it in french. All the pulibc destinated pages are already translated.
Tomorrow I will translate the PSSC and Git Help pages.
That’s all 🙂
What happened related to our project in the last 3 days? One major change and many questions.
First, I spent some time looking for an appropriate battery for our plant. I found a power bank that met our requirements (in fact, we would have needed 2 of them). But they were pretty big. So I proposed to turn the plant from energy autonomous to a plugged product. Our banana tree is not so small so users won’t move it every day, consequently it’s not a problem if it’s plugged. And we decided to choose this alternative.
Then, I looked for an appropriate power supply. This forced us to choose which LEDs we want to use. And for now, we’re still not sure: the most powerful ones consume a lot so we can have only a limited number of them, but the others heat a lot, which can be a problem. We tried to imitate diffusing optical fiber and tested it with both LEDs to help us in our choice, but it didn’t work well with both LEDs. We hope that it will work better with true diffusing optical fiber. Now, we’re waiting for Alexis and Samuel opinion on the LEDs choice
Beside this, I chose a power supply bloc (5V 12A DC out) and found regulators (one for supplying energy to the ICs and another to provide energy to the Flexinol). The LEDs will be plugged directly on the input power line.
I also tested the capacitive proximity sensor with the banana tree: after some tuning, it worked well !! This solution is thus definitely validated.
And finally, I tried to allocate the micro-processor pins (we’ve chosen a STM32F405) to see if 64 pins are enough: we can’t put as many LEDs and Flexinol as we wanted first, but as their number will be limitated by the power supply, maybe 64 pins will be enough.
For the end of this week, we have to finish the electrical schematic. I will take care of the processor part (pins allocation) and of the power supply part. I also want to improve my touch/proximity detection algorithm and if it works well, why not try to detect more complex patterns like sliding.
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.