Xiao Exapansion board w/Xiao BLE, shorted 3.3V power on XEB

Sometime back (Feb 2022) we were seeing an issue with some of the Xiao Expansion boards appearing to short out the on board 3.3v regulator when plugging in the Xiao BLE.

Here is one such thread from Feb 2022

In my case I was just plugging the Xiao BLE into the expansion board, usb connector the to Xiao BLE. (no other power source, battery etc)

The modified broken boards worked for my purpose, just using the SWD interface, but now I find I’m needing to run some I2C functionality, which does not work when the Xiao pins 4/5 are connected to the broken board.

Has the expansion board been modified to help eliminate this issue? If so, is there a board rev number we should look for?

If not redesigned then it sounds like the safe bet is to not connect the Xiao BLE 3.3V pin to the expansion board. Is this the “official” answer.


Hi there,
Wow, that’s a PITA for sure.
I have had exceptional LUCK then , I used several of them ALLOT still do.
all with the SWD & JLink-Plus and 4-wires.(first row of 4)
NEVER had a failure… :bowing_man: :pray:

Until the problem I had between the Keyboard and the Floor, I.E. “Accidently, Unintentionally, in a hurry” plugged the Xiao in with a pin left hanging out the back or front.(don’t do That!) I could feel it getting warm, Quickly removed it and that Nrf52840 sense Xiao, Kinda works :face_with_peeking_eye: It’s a goner. I hurt something it appears and uploads but No Spi or D1 GPIO :-1: NEXT!
A new replacement works as expected and the XEB works as always. YMMV :crossed_fingers:

GL :slight_smile: PJ

Thanks @PJ_Glasso, i guess I will order up another but keep the 3.3 pin disconnected, assuming the expansion is powered from the 5v pin, just to be safer.

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