I have k20d72m based USB host and k20d50m based USB device. I am just wondering how the USB attachment event is triggered on host USB controller? There are two different cases: powering on the host with device plugged in and pluging in the device after host is powered on. What are the differences there?
Reading through some books, it seems like the pulled up D+ from device is the reason for attachment event. But I don't see any pullup on D+ from my USB device design.