Renesas SH7641 Manual De Usuario

Section 20   USB Function Module 

 

 

Rev. 4.00  Sep. 14, 2005  Page 773 of 982 

 

 REJ09B0023-0400 

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. 

USB function

Application

IN token reception

0-byte transmission to host

End of control transfer

Set EP0i transmission

complete flag

(USBIFR0/EP0i TS = 1)

Clear EP0i transfer

request flag

(USBIFR0/EP0i TR = 0)

Write 1 to EP0i packet

enable bit

(USBTRG/EP0i PKTE = 1)

Clear EP0i transmission

complete flag

(USBIFR0/EP0i TS = 0)

End of control transfer

Valid data

in EP0i FIFO?

ACK

Yes

No

NACK

Interrupt request 

Interrupt request