BLDC board for RC car?

I don’t trust my own designs, either. That’s why there is a substantial amount of testing I do before I post anything.

1 Like

Whats about using B-G431B-ESC1: small footprint, supports SimpleFOC, current sensing, i2c

Assuming you want to use this motors as hub/direct drive. I’m currently designing a rc-car with two hub motors in the back tires using B-G431B-ESC1.

-Ability to drive the motors precisely on low speeds without losing lots of torgue (possible with current sensing?)

It is possible but not simple, like shown in this video: https://www.youtube.com/watch?v=oDBqzByuCvg
I also got contact with the smc guys and they reassured me that it is possible with the B-G431B-ESC1 board cause it has a powerful chip on it which you need for high torque sensor-less control

You will need liquid cooling.

I drove my rc car with a Skystars Slim40A 40A ESC, which is even smaller than the B-G431B-ESC1 and it doesn’t get hot, only a bit warm without any cooling.

here is a video

I want sensor-less low torque at startup so I’m experimenting with the B-G431B-ESC1 but i cant get to work. Will update soon if i get it to work. On all my tests the board gets really warm even with very little load. So there are two options i do something compliantly wrong or the board is bullshit

Thanks, that helps a lot! Turns out, my time on this project is ticking, so I’ll need to figure out what board will work and is in store in Europe, as i don’t have time to wait 4-6 weeks for shipping. The STEVAL is available, as is the B-G431B-ESC1, with the latter being 1/5 the price.

@Lukas_Pfitscher I’ll probably give the B-G431B-ESC1 a shoot, as it’s cheap and deliverable soon. I’ll let you know how I’m doing when it arrives. I’ll need two boards to drive both motors, right? I checked your repo, but there’s another ESC listed

Yeah right you need two of them.

But after two days of testing, i can’t get it to run without getting extremely warm.
i searched for issues and i found this FETs are connected to V+ with a single Via

Which if true would be a total fail but could also be me not knowing how to test this esc, here is what i did. I will write to STM directly, maybe they can help

Wow, that would be a severe design flaw, if that’s the case… :-/ just goes to show even big companies make mistakes, and you should always double-check everything!

1 Like

You might want something like Odrive or VESC.
Thats more reliable and mature.

1 Like

IIRC ST said they fixed the flaw back in Feb 2021 and produced a new batch with C1 revision. Could it be you either got an old revision, or they haven’t really fixed it?

Also, a plugged via carries 2A to 3A depending on diameter, but still it was a problem.

1 Like

Not having anything against those, I’m sure they are good for the original purpose. I tried both and then chose to go for a custom designed board and SimpleFOC with some extra custom code on top. Opaque firmware, and insufficient support are their two top issues. Also the support is more or less non-existent for a commercial solution (online board forum).

I keep saying this but there is a reason a commercial BLDC board from a proven manufacturer as Siemens or the likes costs a couple thousand $ compared to $100 odrive or vesc board.

Again, depending on your use case, they may work great.

Caveat emptor.

Cheers,
Valentine

1 Like

Also take a look at Moteus, if considering ODrive/VESC… Moteus is also pretty nice.

1 Like

I’m not sure where to look for revision number

by feeling the temperature with my finger it is in the area where the via is.
But it is really strange that the ESC just can handle 1A, without any switching of the mos fets, just set output to high(tested it)

Which via, could you mark it?

Revision C01. Thats the last one. I mean newest revision. Check on the schematics if they fixed it, its posted on stm website.

via isn’t visible cause it’s multi-layer PCB
just click the link here

Checked the gerber. MB1419B is affected, MB1419C not.

i think it is a good idea, dual motors on RC without centrel driveshaft

1 Like

Thanks for your input everyone! The STEVAL board is on the way, sadly it’ll have to wait until i’m out of isolation and feeling better…

I got a cheap Basecam BGC3.0 clone from the local classifieds in the meantime, but i can’t find anything regarding pinouts or usage not regarding gimbal applications with the GUI. Does anyone know if that board is usable at all? Its this one, just called BGC 3.0 control panel: https://m.media-amazon.com/images/I/61hSo7EeBCL.AC_SY355.jpg

It came with 2x 2208 80kv gimbal motors as well.

Hey, it is useable, but more in open loop than closed loop mode…

The AtMega328 is at the very bottom of the performance scale of MCUs that can run SimpleFOC, so asking it to do 2 motors with I2C sensors (slow!) in closed loop control is a bit much. The problem here is also that I2C is a slow protocol, and reading 2 I2C sensors per loop iteration slows things down a lot.

Open loop on 2 motors should be no problem.

I can’t really remember, I think maybe to program it I had to first download an Arduino Bootloader onto it, and then I could program it as an “Arduino Nano Pro”.

I mapped the pins of the version I have, but be warned that yours could be a bit different:

Mapping pins is fairly easy using a multimeter in “beep mode”.

Start with a very simple sketch, and once you have it working, can download to the board, see Serial output for debugging, etc, then you should be ready to try to move those motors…

But on the whole you may want to wait for the STEVAL… Running SimpleFOC on the STM32 MCU will be much better!

2 Likes

Thanks @runger! I actually got it working fine once i mapped the pins and burned the bootloader. But yes, its mostly usable for open loop.
The STEVAL-GMBL02 just arrived, and i’m eager to get started. I’m just really unsure about how to actually flash code to it. Could you maybe guide me to how i can use the Arduino IDE with it? I’m not sure which bootloader to flash, if any… I figured out that i can burn the bootloader with OpenOCD via Raspberry Pi and SWD, but i would like to use the Arduino IDE.

The Steval GMBL seems like a much harder to learn board than the BGC3, i’m in way over my head. But i hope i’ll get it running once i figure out how to program it.

Hi there! STM32 is well supported in Arduino, so it should not be too hard to get up and running.

First order of business is the way to program it - the simplest is ST-LINK. A ST-LinkV3Mini is all you need and the cable it comes with connects directly to the board. The board should also have come with an adapter to connect it to the ST-Link section of a Nucleo board, but that seemed a bit complicated to me.
You may be able to program it over USB and/or serial as well, but these things can be trickier than st-link from the software side.

On the Software side, install the STM32CubeProgrammer, a free tool from ST-Micro. Using this tool you can communicate with the MCU and flash firmware files, etc… its handy to debug problems.

In Arduino IDE you have to use the board manager to install the STM32 framework. Add the following URL to your board manager URLs in the Arduino settings:
https://github.com/stm32duino/BoardManagerFiles/raw/main/package_stmicroelectronics_index.json

Then you can wait for it to finish installing them, restart the IDE, and then you should have lots of additional boards from ST-Micro to choose. The one you want is a “Generic STM32 F3 series”.

After that you can choose different options like the type of connection, etc… which Arduino IDE are you using? The old one or the new 2.0.0 series one? I can send some screenshots…

1 Like