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USB Device Controller
Figure 5.
Non-Isochronous IN Transaction Phases and Interrupts
Successful data transfer to USB Host. (Endpoint STAT_FLG.FIFO_EN bit was set
when token was receiced.)
In Token
After interrupt, EP's TX FIFO is empty.
No data transmitted by the LH. (Endpoint STAT_FLG.FIFO_EN bit was clear when
token was received.)
In Token
EP TX FIFO is unchanged by this USB transaction.
EP stalled. No data transmitted by the LH. (Endpoint STAT_FLG.EP_HALTED bit was
set when token was received or an EPO control request error has occured.)
In Token
EP TX FIFO is cleared by this USB transaction.
EP TX Data Error during transmission.
In Token
EP 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
3.4.1
Non-Isochronous IN Endpoint Handshaking
116
Universal Serial Bus (USB)
Data
NAK
EPx TX interrupt
(SYSCON1.Nak_En=1)
STALL
EPx TX interrupt
Data
(w/ error)
Per USB specifications for IN transactions, the USB host can provide only one
of two handshakes to the USB function during the handshake phase: ACK or
no handshake at all. The first indicates successful transfer (first case shown
in Figure 5), and the second indicates that the host received a garbled data
packet (last case shown in Figure 5).
ACK
EPx TX Interrupt
Ì Ì Ì Ì Ì
Stage not
executed
Ì Ì Ì Ì Ì
Ì Ì Ì Ì Ì
Stage not
executed
Ì Ì Ì Ì Ì
Ì Ì Ì Ì Ì
No handshake
received
Ì Ì Ì Ì Ì
STAT_FLG bits after
interrupt
0
0
0
1
STAT_FLG bits after
interrupt
(SYSCON1.Nak_En=1)
0
0
1
0
STAT_FLG bits after
interrupt
1
1
0
0
or
0
1
0
0
SPRU761A
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