USB Transactions
13-58
Figure 13–4. Non-Isochronous IN Transaction Phases and Interrupts
IN Token
ACK
NAK
STALL
Successful data transfer to USB host (endpoint STAT_FLG.FIFO_En bit was set
No data transmitted by LH (endpoint STAT_FLG>FIFO_En bit was clear when
Endpoint stalled. No data transmitted by LH (endpoint STAT_FLG>EP_Halted bit was
set when token was received or an EP0 control request error has occurred).
Endpoint X TX interrupt
Data (w/Error)
Endpoint TX data error during transmission.
After interrupt, endpoint TX FIFO is empty.
Endpoint TX FIFO is unchanged by this USB transaction. No interrupt occurs. STAT_FLG is
unchanged.
Indicates a packet received by the device
Indicates a packet sent by the device
Data
Stage not
executed
Stage not
executed
No handshake
received
when token was received).
STAT_FLG bits after
interrupt
ACK
ST
ALL
EP_Halted
NAK
1
0
0
0
STAT_FLG bits after
interrupt
0
0
0
1
STAT_FLG bits after
interrupt
0
1
1
0
0
1
0
0
or
(SYSCON1.Nak_En=1)
ACK
ST
ALL
EP_Halted
NAK
ACK
ST
ALL
EP_Halted
NAK
(SYSCON1.Nak_En=1)
token was received).
IN Token
IN Token
IN Token
Endpoint TX FIFO is unchanged by this USB transaction.
Endpoint TX FIFO is unchanged by this USB transaction.
Endpoint X TX interrupt
Endpoint X TX interrupt