When I plug a BOS1901-Kit on a USB port, other boards already connected are triggered (red LED turns on).
Date Added: 2018-11-23
This may occur if one BOS1901-Kit already plugged is used by the Operating System (Windows) as the main output device (speaker). When the other BOS1901-Kit is plugged, Windows is playing a wave sound on the speaker (BOS1901-Kit) thereby driving a piezo actuator and turning the red LED ON.
Make sure Windows is not using any BOS1901-Kit as its main speaker to avoid triggering playback on the boards every time Windows plays a sound.