[StabiloRose] The Fuck !


[StabiloRose] 9 hours left…

What’s the best adjective to describe ROSE ? The first word which comes is “intense”. Even if our sphere is not perfect. There are a few crazy LEDs near to the poles. The assembly is a bit fragile. We’ll see that tomorrow.

The next step is to read a few tutorials and courses.

[StabiloRose] Yes !

There is so much to say about today. But I’m to excited to write about it right now.


[StabiloRose] Today was not that bad

Yet, I would not have said that a few hours ago. Since this morning, I have not been productive. First, I was not able to fix a corrupt stack. But, thanks to Natolumin, the problem have been solved since 7 pm. I could not fix the calibration of the LEDs. To sum up, all I did until this evening was making a few hole and the assembly of the PCB support (and a trip to bricorama). Nothing really useful.

However, thanks to the team, “we” obtained good results during the night, a few bug fixes and features implemented. And it is good to see that the project complete its PSSC.

For the anecdote, I fixed the calibration issue about an hour ago. In one hemisphere, one of our strip was reversed. The problem is trivial. You spot the beginning and the finishing LEDs, then flip the calibration data. However, when you swap cells like this with libreoffice, it automatically adapts formulas such that the other column remains identical. What a great idea ! For me, the opposite behavior is so obvious that I have not even thought about checking that. Anyway, it is ok now.

Good night.

[StabiloRose] First images and animations

Today, we finally mapped our first images and animation and the result is great. The first images were a bit distorted because of the start frames of the SPI, they included a gap which was visible near to the poles. For the moments, the images and animation are generated “inside” the ball. The next step is to download them from a server.

sr rainbow

[StabiloRose] Calibration first step OK

With Anatole we calibrated the first hemisphere of our ball, i.e. getting the spherical coordinates of each of the 182 LEDs, according to their position on the strip. We entered the data into our little homemade simulator and run the same test that was done yesterday. We turned on each LED, one after the other in the order of the strip.

The simulation and the experiment give the same pattern \o/ So far, so good.

Artur and Clément are currently calibrating the other part.

SR simu gif

[StabiloRose] Building tools

Like the prehistoric man, the rose student builds tools to adapt to his environment.

Sr tool1

Sr tool2

Sr tool3Sr tool4


[StabiloRose] 3D printing is so magic

It fits perfectly 🙂

StabieloRose 3D printing

[StabiloRose] Soldering completed

After the black magic episode and a few short circuits, the placement and soldering is now over. Here is a quick video of a test. I’ll show you more tomorrow 🙂

[StabiloRose] Advanced Black Magic

Today was my first experience with signal integrity. As Artur said, our day was devoted to soldering. After making the poles, we decided to make a short test. We used the same program we made to test the leds strips. On Artur’s hemisphere, everything went fine. All the commands were working well. With mine, it was more a random color generator. At first I thought it was a short circuit. After cutting and resoldering a few wires, I always had the same problem.

After a few experiments with a logical analyzer, I came to this conclusion. My strip was working only if I monitored the clock signal. Could you imagine that ?!?

Thanks to Alexis, who probed the board everywhere, the mystery was elucidated. Even if the SPI frequency was not high (10MHz), the wires brought an inductive effect which distorted the signal. This effect was compensated by the capacitive effect of the logic analyzer.

For our final system, we will use ribbon cables.