Interrupt Request From Usb Function; Interrupt Sources; Timing Of Data/Handshake Packet Receive Interrupt Request Generation; List Of Sources Of Interrupts From Usb Function - NEC switch User Manual

8.6 Interrupt Request from USB Function

8.6.1 Interrupt sources

Interrupt request sources generated by the USB function fall into the following five categories.
Note
Type of Interrupt Priority
Maskable 1
2
3
4
5
Note The priority is the order of priority when multiple maskable interrupts are generated simultaneously.
(1) Token packet receive interrupt (INTUSBRT)
Upon EOP detection during token packet reception, an interrupt request signal is generated and an interrupt
request flag (USBRTIF) is set. If ADRRST (bit 2 of the token packet receive result store register (TRXRSL)) is
0, no interrupt request is generated because a token packet of another device exists on the bus.
(2) Data/handshake packet receive interrupt (INTUSBRD)
Upon EOP detection during data/handshake packet reception, an interrupt request signal is generated and an
interrupt request flag (USBRDIF) is set regardless of error at reception.
If DINTEN (bit 1 of the data/handshake packet receive mode register (URXMOD)) is set to 1, an interrupt
request (receive status synchronous interrupt) signal is generated when 11B is detected by the ID detection
buffer.
Figure 8-23. Timing of Data/Handshake Packet Receive Interrupt Request Generation
Sync
INTUSBRD
(DINTEN = 0)
INTUSBRD
(DINTEN = 1)
DINTEN: Bit 1 of data/handshake packet receive mode register (URXMOD)
CHAPTER 8
Table 8-4. List of Sources of Interrupts from USB Function
Name
INTUSBTM USB timer overflow
INTUSBRT EOP detection when a USB token packet is received
INTUSBRD EOP detection when a USB data/handshake packet is received
INTUSBST EOP detection when a USB data/handshake packet is transmitted
INTUSBRE Detection of transition from J state to K state or SE0 on the USB bus
Data0 Data1
Packet ID detected
Data packet
receive status
synchronous interrupt
User's Manual U12978EJ3V0UD
USB FUNCTION
Interrupt Source
Trigger
DataX CRC16
Data/handshake packet
receive interrupt
Vector Table
Address
0006H
0008H
000AH
000CH
000EH
EOP
EOP received
127