Hi,
this is probably a stupid question, but can I use a Quad USB Isolator HUB (see here) to control 2 ODrives and prevent groundloops? Here is a diagram:
Or is there still a groundloop between the two odrives here?
best regards
Or is there still a groundloop between the two odrives here?
Yes there is still a ground loop between the ODrives. But it is not so much of a problem, especially if you can keep the wires short and low resistance/inductance.
Please make sure that the wires to the power supply are sufficiently oversized to minimise voltage drop.
Also, have you considered CAN instead of USB? It tends to be a LOT more robust.
CAN is able to handle a volt or two of common-mode voltage, whereas USB is sensitive to a few millivolts.
Thanks!
But I don’t quite understand why the voltagedrop in the ODrive power supply wire matters?
I’d love to move away from USB, but then I’d have to reimplement almost the entire communication code on both odrive side and client side. Also, how would I update the firmware without an USB connection? I do that all the time, and I cannot attach and detach an USB cable everytime (that’s very timeconsuming in my setup).
What about UART? Can odrivetool connect with that?
It’s not the voltage drop in the power supply wire, it’s the inductance in the high current path, which can cause a large DC voltage transient and cause stray currents / voltages on the USB wires, frying things.
Basically the answer to all of those other questions is “ODrive v4”. For now, your USB isolators should work fine.
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