False start

Today Xavier and I soldered an ESC to the motor in the Phyllo structure (in truth, after struggling for a long time, we asked Karim Ben Kalaia to show us the way). We just wanted to see the power consumption of the motor while bearing a load, and set up a better configuration for the speed feedback.

Sadly, when we tried to turn on the motor, it didn’t work, creaking and hiccuping for a few moments and then stopping. We noticed that it was really difficult to turn with the hand comparing to the other motors we have. We removed all the load (the PVC plate and the axis) so that the motor can turn freely, but we got the same result.… Read more

Bulletin boards

Ready to roll

After a few days (or weeks) of proofreading, three of our PCBs are ready for production : top PCB, petal PCB and processor PCB. You can find the final version of our schematics for these PCBs attached to this article.

We will need 62 petal PCB, 12 processor PCB and one top PCB for each phyllo. As we plan to make 3 Phyllos, it’s a lot of PCBs, but apart from the top PCB, they are all in two layers and quite simple. The tough part will be to connect them together and place them inside the sculpture.… Read more

STM32 : 1, ESP32 : 0

Since Friday, I’ve been working on DShot generation with Xavier. As explained in his last post , we wanted to use only an ESP32 on the bottom PCB. 

First try of DShot with an ESP32

So last Friday we tried generating DShot with an ESP32 DevkitC and starting our motor with it.

After familiarising ourselves with the ESP API reference, we managed to generate a DShot signal on the SPI bus of the ESP32 using DMA. The idea is to send a DShot bit as an 8-bit SPI frame with the first 3 bits high to send a 0 and the 6 first bits high to send a 1, as explained in this post.… Read more

IRksome AGC

IR for neighbours detection

The past few days, Xavier and I did some more IR tests. 

The first thing we wanted to measure is the reaction time of the receiver.

By logging the times the emitter was turned on and off, we realised the receiver’s reaction to toggling the emitter was systematically delayed between 150 and 250µs. This is not surprising as it perfectly matches the datasheet specification. In any case it’s not a problem because it is short enough and also consistent.

Then, we set out to see whether adding 3D-printed materials between the emitter and the receiver would introduce a delay, and if so, measure this delay.… Read more

Ground control to RoseAce team

Ground transmission

We talked to Alexis this afternoon about ground transmission, and the solution we will finally go with is a mixture of those proposed in yesterday’s post. We will use wires soldered to the main PCB, and fix the GND wire to the axis with a sleeve clamp. Here is a diagram to present it:

@RoseAce : Could you please give us a hand ?

How many ball bearings did you use for VCC transmission in your project ? Thanks in advance for your help 🙂

Update on mechanical architecture

This past few days, Vlaya, Xavier and I also worked on the mechanical architecture of our Phyllo. We’ve already made several posts on this subject, but we still have doubts and questions. Your opinions and experiences are much welcome.

General architecture

The Phyllo (the printed shell of the petals) rests on a circular PVC plate of 25cm in diameter. The main PCB is attached on the top of this PVC plate. The PVC plate is fixed to the axis by a metal piece that the school mechanic will machine for us.

Then, going down, we find the two ball bearings carrying VCC.… Read more

Lots of IRons on the fire

Since Friday, Xavier and I have worked on the placement and routing of the main rotating PCB. We have a lot of constraints to place the components of this PCB, notably for the IR which is used for the detection of other Phyllos and the reception of the common time reference, and the IrDA, used to communicate between the fixed and mobile parts.

IrDA

The IrDA would be used to send speed commands from the rotating part to the fixed PCB below, which controls the motor. This fixed PCB will handle the feedback control of the motor, so we really only need to send it a target speed with the IRdA.… Read more

PCB newcast

This week, as well as the previous ones for most of us, was devoted to PCB design. During this work, several changes were made to our design. Here is a summary and some details. The overall structure remains the same as what Marc described in this post. Let’s go through the modifications for the 5 PCBs.

Main board

We have made many modifications to this PCB.

  • First concerning the Wifi module : we wanted to use the AMW006 module because the OS seemed convenient and it is supposed to have less bugs than the ESP32. But we discovered that the compilation chain has to be used in windows, so we decided to use the ESP32 instead (the DevkitC so as to flash easily).
Read more

IRoning out the Phyllo detection

Back to school after the holidays, we ran tests to validate our idea for detecting other Phyllos with IR radiations. Quick reminder, we had ordered two powerful IR transmitters (LTE-R38381S-ZF-U and SFH 4441) and several receivers, some in AGC2 (TSOP2256 and TSOP4856) and others in AGC4 (TSOP4456). Signal management is a little different depending on the type of gain control (AGC): some receivers are more suitable for noise reduction and other lower detection times.

Protocol

We will briefly go through the IR detection protocol once again. 

First of all, Phyllos give themselves a unique identifier by communicating via Wifi.… Read more

Update on Phyllos detection

Magnetic deception

Last week, we thoroughly tested the MPU9250 that Alexis lent us. At first glance, it looked a lot more promising than the TLV493D-A1B6 MS2GO () we tried before : the range is way better ! Unfortunately, magnetic detection is more complicated than we first thought and it looks like it’s not going to cut it.

You can take a look at this post to remind you of the detection scheme we had in mind.

Essentially, the idea is to use electromagnet in every Phyllo that can be turned on and off, so as to detect the Phyllos one after another, and use Wifi or Bluetooth to coordinate.… Read more