A friend asked me for advice regarding a lock system based on iButtons as keys.
There are some doors, and a 1-wire bus along the way, connected to iButton readers and door locks. (let's skip the complexities of turning 1-wire command into physically opening a lock, that's for a different question...)
Users are issued iButtons - one per person - and the system authorizes given iButton to open a given set of doors. Except there's a caveat: if I insert the iButton into a reader, the system will know iButton[id] has been plugged in. No info which of the multiple readers. No info which of the authorized doors to open.
So - given a single 1-wire bus, what would be a practical way to determine, where (into which reader along the bus) the button has been plugged in?