W1: Enumeration


At system boot, you may need to enumerate your bus
You can skip this step if you feature a single device

The "search rom" command is designed to resolve conflicts:
The master writes the command
It reads back one bit and the negation of the bit
It then writes the bit it wants to select

If you read two zeroes, there is a conflict ("discrepancy")
You can choose which branch you follow and come back later
See AN187 for a good description and a ugly implementation

This enumeration takes 10-20ms for each device
Fortunately, you do it once per boot.