Yesterday Sibille and I brought the Phyllo structure with the faulty motor (see this post) to the school mechanic, Mr Croullebois. We disassembled the structure, and it turns out the motor shaft goes slightly lower than the motor base, so when we screwed it tight it would scrape against the aluminum plate underneath.
Mr Croullebois bored a depression in the middle of the plate so we wouldn’t have this problem anymore, and then we reassembled everything with the other motor that we used for tests and knew to be working. The motor that was in the structure spins more freely now, and we managed to make it run, but there is a weird creaking sound from time to time.… Read more
Today we all brainstormed about the software architecture.
Since we are still waiting to receive the Hall and optical sensors for the speed feedback aspects, we turned our attention to the rest of the Phyllo.
While Marc and Vlaya worked on how to organise the software for the main board – which they will tell you all about in an upcoming post – Sibille and I looked into the LED-driving PCBs. Their role is simple :
Receive color configuration for each LED and control commands via SPI as discussed in this post
Configure and control the timers to generate the appropriate PWM signals to light the LEDs
Since these tasks are simple enough, we plan to forego using an OS and instead write bare-metal code.… Read more
Today the school mechanic made great progress on the physical structure of our first Phyllo:
We still have to add the 5V transmission ball bearing right above the top square aluminium plate, as discussed in this post. We haven’t yet received the PVC tube we’ll use to electrically insulate this ball bearing from the shaft, which will be connected to the ground. As soon as we have it assembled we’ll do a test to check the power transmission to the rotating part.
Recently Alexis took the design decision to drop the IrDA idea (see this post) and to instead use an additional ESP32 to communicate between the rotating main board and the bottom PCB (which is in charge of controlling the motor).
So now the bottom PCB has an ESP32 for the purpose of receiving speed instructions from the main board over Wifi.
Yesterday, I wondered whether we could actually drop the STM32 processor on the bottom PCB and let the ESP32’s CPUs handle everything. We decided that the question was worth investigating, as there really isn’t that much to do on the bottom PCB.… Read more
Today we received the AIKON 45A SEFM ESCs we ordered a while ago. Actually that’s a lie: these ESC were received before today, but no one told us until Alexis recalled seeing them when we told him we were waiting for them and pulled them from the top shelf of the cabinet in the back of the classroom. We’ll let it slide, whoever it was, but just this once.
Today, I tried to reflash the built-in ESC of our new motor, EP4108.It runs BLHeli firmware, and we would like to update it in order talk to the ESC via a relatively new protocol, DShot, instead of the age-old PWM control. Short story long, I didn’t manage to do it.
Still, here’s what I tried.
As mentioned in this post, the motor has a 6-pin “flashing port” – except there is no provided connectors and absolutely no instruction on how to reflash the ESC. In fact, we don’t even know what ESC it is. All we know is that it runs some version of the BLHeli open source firmware.… Read more
Last Friday we received new motors : the EP4108 320KV with built-in ESC.
We’re particularly interested in those because they have a reflashable integrated BLHeli ESC. It turns out that, starting with BLHeli_S v16.5, which is an open source ESC firmware, a new protocol is supported to replace the old PWM control method : DShot. It’s a serial protocol where speed information is encoded in 16-bit frames, instead of analogically in the duty cycle of a PWM signal.
There are three generations of BLHeli firwmare : BLHeli, BLHeli_S, and BLHeli32 (wich is no longer open source), each with several versions.… Read more