r4f2456 Renesas Electronics Corporation., r4f2456 Datasheet - Page 981

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

16.5.2
The above flowchart shows the operation in the case of in section 16.9, 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.
No
Cable Connection
Protocol processing block reset
USB bus connection interrupt
Wait for setup command
reception complete interrupt
Protocol processing block
reset release
USB cable connection
D+ pull-up enabled?
Cable disconnected
General output port
Bus reset reception
Bus reset interrupt
IFR0.VBUSF = 1
VBUS pin = 0 V
IFR0.BRST = 1
USB function
Yes
Figure 16.3 Cable Connection Operation
Interrupt request
Interrupt request
Firmware preparations for
start of USB communication
Wait for setup command
reception complete interrupt
As soon as preparations are
completed, enable D+ pull-up.
Clear bus reset flag.
Clear VBUSF flag.
USB module interrupt
setting
Rev. 1.00 Sep. 19, 2008 Page 951 of 1342
(IFR0.VBUSF)
(EP0 to EP3)
(IFR0.BRST)
Clear FIFOs.
Section 16 USB Function Module (USB)
Application
REJ09B0467-0100
Initial
settings