HD6417641 RENESAS [Renesas Technology Corp], HD6417641 Datasheet - Page 823

• Manufacturer Part Number: HD6417641
• Manufacturer: RENESAS [Renesas Technology Corp]

Status Stage (Control-OUT): The control-OUT status stage starts with an IN token from the
host. When an IN token is received at the start of the status stage, there is not yet any data in the
EP0iFIFO, and so an EP0i transfer request interrupt is generated. The application recognizes from
this interrupt that the status stage has started. Next, in order to transmit 0-byte data to the host, 1 is
written to the EP0i packet enable bit but no data is written to the EP0i FIFO. As a result, the next
IN token causes 0-byte data to be transmitted to the host, and control transfer ends.
After the application has finished all processing relating to the data stage, 1 should be written to
the EP0i packet enable bit.
0-byte transmission to host
(USBIFR0/EP0i TS = 1)
Set EP0i transmission
End of control transfer
IN token reception
in EP0i FIFO?
complete flag
Figure 20.9 Status Stage (Control-OUT) Operation
Valid data
USB function
Yes
ACK
NACK
No
Interrupt request
Interrupt request
Rev. 4.00 Sep. 14, 2005 Page 773 of 982
(USBTRG/EP0i PKTE = 1)
(USBIFR0/EP0i TR = 0)
Clear EP0i transmission
(USBIFR0/EP0i TS = 0)
Write 1 to EP0i packet
End of control transfer
Clear EP0i transfer
Application
complete flag
Section 20 USB Function Module
request flag
enable bit
REJ09B0023-0400