Datasheet

Section 22 USB Function Module (USB)
Rev. 2.00 Aug. 20, 2008 Page 879 of 1198
REJ09B0403-0200
22.5.7 EP3 Interrupt-In Transfer
USB function Application
IN token reception
Data transmission to host
Set EP3 transmission
complete flag
(IFR1.EP3 TS = 1)
Write data to EP3 data
register (EPDR3)
Write 1 to EP3 packet
enable bit
(TRG.EP3 PKTE = 1)
Clear EP3 transmission
complete flag
(IFR1.EP3 TS = 0)
Write data to EP3 data
register (EPDR3)
Write 1 to EP3 packet
enable bit
(TRG.EP3 PKTE = 1)
Valid data
in EP3FIFO?
Is there data
for transmission
to host?
Is there data
for transmission
to host?
No
Yes
No
Yes
No
Yes
NAK
ACK
Note: This flowchart shows just one example of interrupt transfer processing. Other possibilities include an
operation flow in which, if there is data to be transferred, the EP3 DE bit in the data status register is
referenced to confirm that the FIFO is empty, and then data is written to the FIFO.
Interrupt request
Figure 22.17 Operation of EP3 Interrupt-In Transfer