Don't know about BT, but why do you say USB is a mess? I have implemented USB device from scratch long time ago, and the protocol was pretty pleasant. It satis

Don't know about BT, but why do you say USB is a mess? I have implemented USB device from scratch long time ago, and the protocol was pretty pleasant. It satisfied its main goal: being simple to implement with minimal resources. Sure, there are things that could be improved, I'd say 512 mA power limit is the worst. And some sort of auto-poll mechanism on hubs wold be nice. And maybe IRQ-like bus state to save power? But those are pretty minor things. (Of course the software part is a mess - a lot of drivers have no error recovery whatsoever. But this is not protocol's fault)