This is reading, not writing

Ah I see thanks

Ben Eater has a great video on it.

I’m not watching a video, but appreciate the pointing in the right direction

USB sends a dummy zero every few consecutive 1s for framing purposes

Huh, TIL about Bit-Stuffing and Framing Bits

Bit stuffing is the insertion of non-information bits into data … is used for various purposes, such as for bringing bit streams that do not necessarily have the same or rationally related bit rates up to a common rate

Framing is the process by which, while receiving a stream of fixed-length frames, the receiver identifies the frame boundaries, permitting the data bits within the frame to be extracted for decoding or retransmission. A common practice is to insert in a dedicated time slot within the frame, a noninformation framing bit that is used for synchronization of the incoming data with the receiver.