SH7641 Datasheet, PDF (816/1036 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family / SH7641 Series

Section 20 USB Function Module
20.4 Operation
20.4.1 Cable Connection
USB function
Cable disconnected
VBUS pin = 0 V
UDC core reset
USB cable connection
Application
USB module interrupt
setting
As soon as preparations are
completed, enable D+ pull-up
in general output port
Initial
settings
No
General output port
D+ pull-up enabled?
Yes
USBIFR1/VBUS = 1
Interrupt request
USB bus connection interrupt
Clear VBUS flag
(USBIFR1/VBUS)
UDC core reset release
Firmware preparations for
start of USB communication
Bus reset reception
USBIFR0/BRST = 1
Bus reset interrupt
Interrupt request
Wait for setup command
reception complete interrupt
Clear bus reset flag
(USBIFR0/BRST)
Clear FIFOs
(EP0, EP1, EP2, EP3)
Wait for setup command
reception complete interrupt
Figure 20.2 Cable Connection Operation
The flowchart in figure 20.2 shows the operation in the case for section 20.8, Example of USB
External Circuitry.
In applications that do not require USB cable connection to be detected, processing by the USB
bus connection interrupt is not necessary. Preparations should be made with the bus reset interrupt.
Rev. 4.00 Sep. 14, 2005 Page 766 of 982
REJ09B0023-0400