WebIDE locks up while loading require("neopixel") on Nordic nRF52840 Dongle

thanks, got it, so LRCK goes nowhere but must be used to enable i2s and some clock is produced there. Then it is indeed not a good idea to connect this to reset pin :-)

So there are couple of pins not connected at all on 52840 dongle, one is P0.16 on the picture posted above.

just tried D16 on dongle clone (E104-BT5040U) and writing 1 or 0 does nothing, reading gives true by default and false when configured as D16.mode("input_pulldown"), so I guess the pin is floating. D23.write(0) reboots to bootloader indeed