NEC switch - Manual (Page 149)

CHAPTER 8 USB FUNCTION
User’s Manual U12978EJ3V0UD
149
Figure 8-29. Flowchart of Sync Detection/USBCLK Detector Operation
N
Y
N
Y
N
Y
Y
N
Idle state
USB clock
oscillation start
Detect last Sync bit
Receive next bit
Receive next bit
Output 0
from NRZI decoder
Output 0
from NRZI decoder
Output 1
from NRZI decoder
Output 1
from NRZI decoder
Did state change
to K state?
Was EOP receive
signal set?
Did bus state
change?
Did bus state
change?
USB clock stop
Idle state
Sync detection