NEC switch - Manual (Page 142)

CHAPTER 8 USB FUNCTION
User’s Manual U12978EJ3V0UD
142
Figure 8-25. Flowchart of Transmit/Receive Pointer Operation (3/7)
(2) Data/Handshake packet reception (1/2)
N
Y
Y
Y
N
Y
N
EOP
Y
Y
N
1
Y
EOP
Y
N
N
N
Y
2
Idle state
Set USBPOW to 10H
USBPOB increment
USBPOW increment
Set USBPOB to 00H
Transmit/receive
signal?
USBPOB
overflow?
USBPOW
= 11H?
Does bit stuffing
signal = 1?
USBPOB
overflow?
Does
USBPOW match
DRXCON?
USBPOB increment
Set USBPOW to 70H
Does bit stuffing
signal = 1?
Bit normal write?
Bit normal write?
HSSTAT = 1?
Data/handshake reception
Set DBYER flag
Set CRC16 execution
start signal
Idle state
Set DBYER flag
Idle state
Y
DBYER: Bit 5 of data/handshake packet receive result store register (DRXRSL)
DRXCON: Data/handshake packet receive byte number counter