I know some computer USB could handle some bad connection (by blocking the port, which need to reboot the computer). But I wonder if a NodeMCU 8266 offers some protection.

1 Answer 1


Most USB ports are shut down when an over-current event is detected.

There is nothing in a NodeMCU that can prevent an over-current event in the case of things like short circuits. The 5V (or VIN on some versions) pin is directly (or sometimes via a single diode) connected to the 5V pin of the USB. Cause a short on the 5V pin and you cause a short on the USB.

Protection is designed to be at the port level not the device level so that devices don't have to be forced to comply to protection "standards" that would drive up costs and result in devices being non-compliant and risk damaging the computer.

If you find that you are often causing shorts on the 5V pin and killing (albeit temporarily) your USB ports you should change your working practices.

It can be good to always connect your devices to an external powered USB hub instead of directly to your computer. That way if you kill a port you can just unplug the hub and plug it back in again to reset all the ports. No need to reboot your computer.

Cheap hubs often just have a simple PTC fuse instead of proper over-current protection which can actually be more useful for device developers since the port won't be disabled, just the external power shut off.

Most Arduino boards do incorporate a PTC fuse in the USB power circuitry, but NodeMCU and similar boards don't.

  • Thanks! But instead of USB hub, shouldn't it instead be an "USB insulator?" such as this one ebay.com/itm/…
    – JinSnow
    Commented Dec 4, 2018 at 20:23
  • 1
    You could use an isolator, but a hub is just as good in this situation and a whole lot more useful.
    – Majenko
    Commented Dec 4, 2018 at 21:37
  • Would even the cheapest hub do it? (Not sure of the grammar of this one!)
    – JinSnow
    Commented Dec 5, 2018 at 14:01

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