F-Of-C - open-source Free-Of-Charge vesc6 board in development. Schematics available


Version 0.1
So this is the open source Free-Of-Charge board I’m trying to develop.
All components well stocked and cheap at jlcpcb / lcsc.

SCHEMATICS and KiCad files on F-Of-C github.

This is my first shot at Kicad, so please give me some feedback…


should be hard to put shamans board and yours in a comparative test

Interesting! Do I remember you posted some open source stuff in the past?

Do you have a layout/PCB file? I bought this into KiCAD but couldn’t find one.

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No, sorry, not yet. That’s what I’m about to do, unless you want to do it for me :slight_smile:


Im a complete amateur dude, I wouldn’t be able to do a layout but I am keen to maybe make a couple of these and see what happens

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I might make a couple as well. Can you tell us what you expect the pros and cons to be relative to Shaman’s Cheap FOCer 3?


I’m interested in making a few.

Schematic looks tidy :clap:
2 layer PCB for all those amps sounds like abit of a stretch :sweat_smile:

Any snapshots of the power layout? Overall curious how you solved both logic and power on only 2 layers without accomodating a dedicated gnd plane. :thinking:


OK, so thanks to a couple of serious foc-guys I already got a lot of feedback:

  • 80 kHz cut off freq of current sensing is on the low side. It can go as high as 1.5 mHz apparently.
  • The gain of 50 for the TP181 is high (I knew that but now confirmed). I will go for an op-amp solution instead with a gain of 20.

Also got a lot of suggestions for components, and I might change some stuff. I like to go with tested components.

Thank you.
I will change some stuff and update the schematics before continuing with layout.


The diagram looks good. Why don’t you use the +5V LDO “7805” to reduce the number of components? Secondly, it’s worth adding a physical on-off switch for the controller. After all the updates in EasyEDA, I can help you design the controller

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Ah, so you havn’t gotten to the layout part of things, I’m betting you’ll go for a 4 layer PCB when you do :wink:
you should check out the vesc discord. lot of knowledgable ppl(including vedder from time to time) in there that could assist with any questions you might have.


Yeah, I already checked it out - yesterday, and that’s where I got all the feedback. Some of these guys are really serious about this stuff. Amazing. Me like…


Schematics updated according to feedback on Discord from mxlemming, hackey and Elwin.
Switching power supply now use other component
TP181 changed to TP2604-SR for lowering current sense gain from 50 to 30

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it has an IMU is all I wanted to know. Nice

Will it be feasible / economical to have a batch of fully (or mostly) populated boards made?
I might be interested if there’s going to be a group buy.

(After some for adventurous and resourceful folks have validated the design.)

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I have one component which is not particularly well stocked at jlcpcb. Will have to figure out a solution to this.

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Do you have any pics with the components populated?

Which part are you looking for an alternative?

It’s an op-amp (jlcpcb no. C126446) for current sensing…

Kicad doesn’t let me show any components…

I know people fear SMT, but it may not be reasonable to confine yourself to jlc stock, which frequently changes anyway. If you are using parts that are relatively easy to find by mouser etc., I think it should be fine.

I assume the passive components are 805 or 603. Really, the only bit of tricky soldering here is the stm32 (people often leave bridges hand soldering them). I think jlc will populate this one on request.