If at first you don’t succeed, try, try again

The roller coaster of the marbles tests

Last time, I wrote on this logbook, we were happy, we find a way to control our marbles without a side effect. But we did not think about one thing. With two marbles, our assembly plan works, however, with 9 marbles, it does not.

As you can see, when we cut the current, the marbles came back to another position

On Friday, after this discovery, I was thinking about this problem in my car: We need to keep the marbles near the metal because, without this, they will affect each other. On the other hand, we need to keep them far from the coils since we need to have some distance to make them flip.… Read more

A solid foundation

Last week we met with Alain Croullebois, the go-to guy for mechanical questions at the school. We went to his workshop with the motor we received during the holidays : this Turnigy Multistar 4225-390Kv 16 Poles Multi-Rotor Outrunner. We discussed what the physical structure of the Phyllo could look like.

Here is a global diagram of what we came up with :

The mechanical structure of the whole Phyllo

The Base

For the base of our Phyllo, he suggested stacking two 30cmx30cm aluminium plates 8mm thick, with a separation of 6cm between the two plates maintained by 2cm wide pillars at each corner.… Read more

New Year, new skin

Happy New Year everyone, hope you enjoyed the holidays !!

Today we are going to talk about the latest trends of our hardware architecture.

New PCB disposition to drive the petals

We used to try to drive each LED with its own processor. However we could not manage to get every component to fit on the PCB petals. Moreover, the processors were underused as we barely needed half of their timer outputs. Therefore, further inside the Phyllo, we decided to add a layer with slightly bigger PCBs (let’s call them the petal controllers). They have a STM32F207VIT6 which can drive up to 10 LEDs.… Read more

FPGA architecture, episode 2

The architecture of the FPGA has evolved since the last post.

General architecture

First, since we don’t plan on controlling the rotation speed from the HPS anymore, this feature has been removed from the architecture.

Moreover, the SCLK and GCLK are now generated by each of the 20 LED band controllers since we have enough ouput pins on the FPGA. This results in a simpler design and better signal integrity on these two signals.

Each LED band controller controls a LED driver. More information on the way this driver works can be found on this post.

For the inner memory of the LED band controller we use a dual port, dual clock synchronous RAM, which is proposed in Intel’s recommended HDL coding style for memory inference.… Read more

The PCB puzzle

We made a few major modifications in our design : it turns out flex PCBs aren’t possible. Even though everything isn’t quite decided yet, here is a summary to clarify the situation. I will keep you updated of any major modification 🙂

General design

A Phyllo is composed of three parts:

  • a fixed base,
  • a rotating half sphere placed on this fixed base serving as support for the lighting of the sculpture,
  • a hull made of petals that covers this sphere.

A Phyllo has 78 petals that can be illuminated individually (8 spirals with 6 petals lit by spiral arms, or 13 spirals in the other direction).… Read more

Working anatomy of a Phyllo

Architecture

Here is a diagram summarizing the architecture of a Phyllo, to allow you to have a global vision : 

Some details

This week, we spend a lot of time trying to choose the components. Here are the solutions we explored and the decisions we took.

Motor and ESC

All the animations we will display are based on two or three basic animations : aging petals, de-aging petals and possibly fixed images. Here are simulations to visualize those animations :

Aging and de-aging petals

In order to display those animations without skipping any petal (have a look at this instructable to remember the “skipping petals” part) while flashing the LEDs at 30Hz (ie 30 frames per seconds), the Phyllo has to rotate at : 

AnimationSpeed (RPS)
Aging petals11.46
Read more

Architecture: “The more it’s simple, the more it’s simple”

First, the work of some students

We spend a whole week working with just a few responses from Alexis, so we try on our own to find out how to make our architecture. This is what it would look like

We spend a lot of time exploring the best components, as you may have seen it in our previous posts.

We would have to make a lot of FPGA programming for the I/O expander, but we thought it was our unique solution.

We spend some times looking for a sensitive captor touch with only one key and the way to use it because we wanted to use the sensitive captor touch of an ESP32-WROOM-32D.… Read more

A first look at the FPGA architecture

In order to synchronize the LEDs and create a persistence of vision image, we use a CycloneV SOC.

Here is a first idea of the architecture we might use :

The ARM processor fills a buffer with the next image to be displayed, that is then swapped with the second buffer. It can pull this image from the SD card, or from another source such as the text printing function we plan on adding.

The full buffer is then accessed by a Direct Memory Access (DMA) IP that then sends the relevant cylinder (32 * 128 pixels) to each LED band controller that is then stored in their memory.… Read more