r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 995

• Manufacturer Part Number: r4f2456
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

(5)
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.
Status Stage (Control-Out)
0-byte transmission to host
End of control transfer
Set EP0i transmission
complete flag.
(IFR1.EP0i TS = 1)
IN token reception
Figure 16.15 Status Stage (Control-Out) Operation
in EP0i FIFO?
Valid data
USB function
Yes
ACK
No
NAK
Interrupt request
Interrupt request
Rev. 1.00 Sep. 19, 2008 Page 965 of 1342
Clear EP0i transmission
complete flag.
(IFR1.EP0i TS = 0)
Write 1 to EP0i packet
enable bit.
(TRG0.EP0i PKTE = 1)
End of control transfer
Section 16 USB Function Module (USB)
Clear EP0i transfer
request flag.
(IFR1.EP0i TR = 0)
Application
REJ09B0467-0100