Figure 15.16 Status Stage Operation (Control-Out) - Hitachi H8S/2215 Series Hardware Manual

(5) 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 EP0i FIFO, 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.
USB function
IN token reception
Valid data
in EP0i FIFO?
0-byte transmission to host
Set EP0i transmission
complete flag
(UIFR0/EP0i TS = 1)
End of control transfer
Rev. 3.0, 10/02, page 498 of 686
No
NACK
Yes
ACK

Figure 15.16 Status Stage Operation (Control-Out)

Firmware
Clear EP0i transfer
request flag
(UIFR0/EP0i TR = 0)
Write 1 to EP0i packet
enable bit
(UTRG0/EP0i PKTE = 1)
Clear EP0i transmission
complete flag
(UIFR0/EP0i TS = 0)
End of control transfer