Interrupt-In Transfer: (Ep1I Is Specified As Endpoint); Figure 15.17 Ep1I Interrupt-In Transfer Operation - Hitachi H8S/2215 Series Hardware Manual

15.5.5

Interrupt-In Transfer: (EP1i is specified as Endpoint)

USB function
IN token reception
in EP1i FIFO?
Data transmission to host
Set EP1i transmission
complete flag
(UIFR0/EP1i TS = 1)
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 EP1i data enable bit in the USB data status
register is referenced to confirm that the FIFO is empty, and then data is written to the FIFO.
No
Valid data
NACK
Yes
ACK
Interrupt request

Figure 15.17 EP1i Interrupt-In Transfer Operation

Firmware
Is there data
for transmission
to host?
Yes
Write data to USB endpoint
data register 1i (UEDR1i)
Write 1 to EP1i packet
enable bit
(UTRG0/EP1i PKTE = 1)
Clear EP1i transmission
complete flag
(UIFR0/EP1i TS = 0)
Is there data
for transmission
to host?
Yes
Write data to USB endpoint
data register (UEDR1i)
Write 1 to EP1i packet
enable bit
(UTRG0/EP1i PKTE = 1)
Rev. 3.0, 10/02, page 499 of 686
No
No